Dissertations / Theses on the topic 'Cognitive control theory'

Executive function (EF) and theory of mind (ToM) skills develop rapidly during the preschool years and have been found to directly and indirectly contribute to school readiness. Evidence indicates that EF may influence ToM development, though this relation may not be consistent across children from different backgrounds. Additionally, socioeconomic status (SES) has been shown to affect preschoolers’ EF, while the literature is mixed regarding the effects – if any – that SES may have on ToM development. Though the relation between EF and ToM appears robust across the literature, the possible effects of SES on this relation have yet to be fully explored. As children from low-SES homes are more likely to fall behind at the start of school, and this achievement gap is likely to widen through the school years, it is important to understand how the cognitive components that contribute to school readiness develop and are affected by SES so that we may work toward improving preschool education for children across all socioeconomic backgrounds. The primary purpose of the current study was to determine whether SES affected the relation between EF and ToM among urban preschool children (ages 3-5 years) from various SES backgrounds. In addition to examining the EF-ToM relation, relations among SES, general cognitive skills, EF, and ToM, as well as relations among age, EF, and ToM, were examined. Results from correlational and regression analyses indicated that SES was related to EF but not ToM, and that EF was not related to ToM after controlling for age. Inconsistent with the majority of previous findings, the results did not support the hypothesized link between EF and ToM. However, the findings from this study do add support to the large body of literature pertaining to the positive relation between SES and EF, and provide evidence that ToM may be relatively protected from the negative effects of low-SES among preschoolers. Results also support previous reports of large age-related changes in EF and ToM that occur during the preschool years. The implications for preschool development and education are discussed.

This thesis investigates three hypotheses in relation to the cognitive explanation of normal and problematic gambling behaviour. The "strong cognitive hypothesis" takes the view that if cognitive processes alone account for different levels of play, then the order of the events experienced during a task may be a good predictor of the levels of play. Four large scale experiments are presented focusing on the Illusion of Control, particularly the order effects originally observed by Langer and Roth (1975). Drawing on Hogarth and Einhom's (1992) belief adjustment model an adjusted methodology is employed making the paradigm resemble the real gambling decision making task more closely. The results of the Illusion of Control experiments suggest that the strong cognitive hypothesis can account for gambling in general, but there is no consistent support in favour of its role in explaining differential levels of play. Three questiormaire studies are then presented investigating the two alternative hypotheses assessed in this thesis. The "weak cognitive hypothesis" stipulates that an additional individual differences element is necessary to supplement the strong cognitive hypothesis in order to explain differential levels of gambling behaviour. Individual differences in the level of everyday general dissociation, the enjoyment and engagement in two forms of processing (Rational or Experiential, Epstein 1990), and in the extent to which heuristics and biases are used when making decisions are investigated. Factor analysis for the heuristics and biases investigation, particularly in relation to the understanding of the principle of randomness, reveals some evidence for the weak cogmtive hypothesis. Strongest evidence emerges in relation to the "integrative hypothesis" which stipulates that cognitive factors and processes are only important in relation to and interaction with other variables. The questioimaire studies investigate the role of erroneous beliefs and their relationship with the dissociation experienced within the gambling task. Using Structural Equation Modelling techniques, the results lead towards the generation of a new model of differential levels of gambling and the causal links between these variables and the loss of control are discussed.

The objective of this research is to investigate the power-control problem and analyze the network capacity in cognitive radio (CR) networks. For CR users or Secondary users (SUs), two spectrum-access schemes exist: namely, spectrum underlay and spectrum overlay. Spectrum overlay improves the spectrum utilization by granting SUs the authority to sense and explore the unused spectrum bands provided by PUs. in this scheme, designing effective spectrum-sensing techniques in PHY layer is the major concern. Spectrum underlay permits Sus to share the same spectrum bands with PUS at the same time and location. In this scheme, designing robust power control algorithms that guarantee the QoS of both primary and secondary transmissions is the main task. In this thesis, we first investigate the power-control problems in CR networks. Especially, we conduct two research works on power control for CDMA and OFDMA CR networks. Being aware of the competitive spectrum-access feature of SUs, the non-cooperative game theory, as a standard mathematics, is used to study the power-control problem. Note that game-theoretical approaches provide distributed solutions for CR networks,, which fits the needs of CR networks. However, it requires channel state information (CSI) exchange among all SUs, which will cause great overheads in the large network deployment. To gain better network scalability and design more robust power-control algorithm for any hostile radio-access environments, we propose a reinforcement-learning-based repeated power-control game that solve the problem for the first time. The left part of the dissertation is to study the throughput capacity scaling of the newly arising cognitive ad hoc networks (CRAHNs). Stimulated by the seminal work of Gupta and Kumar, the fundamental throughput scaling law for large-scale wireless ad hoc networks has become an active research topic. This research is of great theoretical value for wireless ad hoc networks. Our proposed research studies it in the scenario of CRAHNs under the impact of PU activity. It is a typical and important network scenario that has never been studied yet. We do believe this research has its unique value, it will have an impact to the research community.

This study employed an experimental design intended to be an analog to the workplace to examine a person by situation interactive effect on OCBs, which were evaluated as prosocial behaviors. This study also sought to provide initial empirical support for the two-stage social cognitive model of OCBs proposed by Hauenstein and Kalanick (2008). Participants were 194 undergraduates. The study was a 2 (Helpfulness) by 2 (Fairness) design. After completing distracter tasks 1 and 2, participants received either a helpfulness prime or a control prime (task 3). Participants then either experienced either a fair manipulation or an unfair manipulation. Results indicated a distinction between the decision to help and helping effort, which has not been thoroughly examined in literature on OCBs. Results revealed main effects for the helpfulness prime and fairness manipulation on the decision to engage in helping. The nature of these effects was that participants helped more when they were primed with helpfulness and when they experienced fairness. However, once helping commenced, there was an interactive effect between helpfulness and fairness such that the helpfulness prime had a stronger effect on participants treated unfairly. Implications for future research on OCBs are discussed.
Ph. D.

Theory of Mind (ToM) refers to the ability to attribute mental states to oneself and other people. In this thesis, I present a new paradigm, the Self/Other Differentiation task, which was designed to assess ToM abilities – specifically, the ability to attribute belief states to the ‘Self' and ‘Other' – in typically developed, healthy adults. By focussing on fully developed ToM abilities, we aimed to increase understanding of how the ToM mechanism is structured and functions in everyday life, and how individual ToM components may differentially relate to executive functioning (EF) abilities. The Self/Other Differentiation task is a computerized false-belief task utilizing a matched- design to allow direct comparison of self-oriented versus other-oriented belief- attribution processes. Using behavioural (response times/error rates) and electrophysiological (EEG) methods, the work presented in this thesis provides evidence of a clear and distinct differentiation in the processing of ‘Self' versus ‘Other' perspectives in healthy ToM. We established a key role of perspective-shifting in ToM, which we hypothesize plays a crucial role in day-to-day communications; shifting from the Self-to-Other perspective was significantly harder (longer and more error prone) than shifting from the Other-to-Self perspective, suggesting that the ‘Self' forms the stem of understanding the ‘Other'. EEG analysis revealed these effects were present across fronto-lateral and occipital-lateral areas of the brain, particularly across the right hemisphere in parietal regions. We provide evidence of these features as universal, core components of the ToM mechanism, with data collected from both Chinese and Western cultures illustrating similar patterns of results. Results regarding the relationship between ToM and EF were mixed, with one study finding that affective EF positively correlates with ToM task performance, whilst non-affective EF does not, and a further two studies finding no such differential relationship. The Self/Other Differentiation task provides the opportunity to establish the features of ‘typical' ToM processes in healthy adults, to further our understanding of how the mature ToM mechanism functions.

The present dissertation deals with how to use the precious wireless resources that are usually wasted by under-utilization of networks. We have been particularly interested by all resources that can be used in an opportunistic fashion using different technologies. We have designed new schemes for better and more efficient use of wireless systems by providing mathematical frameworks. In the first part, We have been interested in cognitive radio networks, where a cellular service provider can lease a part of its resources to secondary users or virtual providers. In the second part, we have chosen delay-tolerant networks as a solution to reduce the pressure on the cell traffic, where mobile users come to use available resources effectively and with a cheaper cost. We have focused on optimal strategy for smartphones in hybrid wireless networks. In the last part, an alternative to delay-tolerant networks, specially in regions that are not covered by the cellular network, is to use Ad-hoc networks. Indeed, they can be used as an extension of the coverage area. We have developed a new analytical modeling of the IEEE 802.11e DCF/EDCF. We have investigated the intricate interactions among layers by building a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and traffic

College-age adults gain weight more rapidly than the general population, with a mean weight gain of ~1.8 to 4 kilograms during their first year at college. The purpose of this pilot RCT was to test the efficacy of a semester long internet weight-loss program based upon social cognitive theory for overweight college freshmen. Qualitative focus groups were used to provide feedback on content of the active intervention. Participants (n=27; mage=18.5±.6; mweight=90kg±18; 74% female) were randomly assigned to the active intervention (Fit Freshmen; FF) or a health information control group and completed baseline and 3 month follow-up measurements. When compared to controls FF participants experienced higher improvement in self-regulatory skills for portion control, fruit and vegetable consumption and physical activity (all pâ s<.05). Consumption of dietary fat and added sugar also decreased significantly for FF subjects when compared to controls (all pâ s<.05) while total energy intake differences were significant (p<.09). Trends in increased physical activity were present, but not significantly different between groups. Finally, FF lost significantly more weight than controls (mdifference=2.2kg; p<0.05) and more fat mass (mdifference=1kg; p<0.09). Themes for content improvement included providing a more detailed meal plan, reducing email contact, and increasing social activity opportunities. Program characteristics that were positively evaluated included the flexible exercise program, incentives for weight loss, and use of an onsite weigh station. This study provides promising outcomes for a scalable internet-based weight loss program for college freshmen and highlights features that could be improved to be more attractive to this population.
Master of Science

The current body of work aims to apply Processing Efficiency Theory (PET) and Attentional Control Theory (ACT) to novel dynamic settings by examining how anxiety influences perceptual-cognitive and perceptual-motor skills. Sporting domains and fall-risk in older adults are studied. Applying ACT to a tennis anticipation paradigm examines whether state anxiety influences processing efficiency and the use of contextual information during anticipation. Processing efficiency was reduced under anxiety, while overall response accuracy was unchanged. Furthermore, skilled performers were seemingly less able to utilise contextual information when anxious. Studies in Chapters 4 and 5 sought to test the predictions of PET and ACT compared with those of Reinvestment Theory (RT) in the field of fall-risk in older adults. In Chapter 4, trait anxiety, alongside increasing dual-task demands, produced processing and motoric inefficiencies through reduced visual planning and mean gait velocity. Furthermore, greater and more variable gait velocity reductions were found in those with higher trait anxiety. By contrast, greater reinvestment levels were associated with poorer visuospatial recall, higher stepping accuracy, plus larger and less variable gait velocity reductions. Chapter 5 further investigates the motoric inefficiencies observed in anxious older adults’ gait. The influences of trait anxiety, movement specific reinvestment, and falls efficacy on body segmental control during adaptive turning are studied. Trait anxiety and falls efficacy were mainly shown to influence differing facets of turning behaviour, though both were associated with greater coupling of body segments (en-bloc rotations), whereas, limited support was offered for RT. Overall, PET and ACT were supported when applied to these new dynamic domains. However, discrepancies are discussed due to testing theoretical hypotheses in more representative environments.

Situation Awareness (SA) is critical commodity for teams working in complex sociotechnical systems and is thus a fundamental consideration in collaborative system design and evaluation. Despite this, SA remains predominantly an individual construct, with the majority of models and measures focused on SA from an individual perspective. In comparison, team SA has received much less attention and this thesis argues that further work is required in the area both in relation to the development of theoretical perspectives and of valid measures, and to the development of guidelines for system, training and procedure design. This thesis advances team SA theory and measurement by further investigating a recently proposed model of SA in complex collaborative environments, the Distributed Situation Awareness (DSA) approach, and by testing a new methodology for representing and analysing DSA during real world collaborative activities. A review of SA theory and SA measurement approaches is presented. Following this, the DSA theory and propositional network assessment methodology are outlined and a series of case studies on DSA during real world collaborative activities in the military and civil domains are presented. The findings are subsequently used to explore the concept of DSA and the sub-concepts of compatible and transactive SA. In conclusion, a model of DSA in complex collaborative systems is presented, and a series of system design guidelines for supporting DSA are outlined.

Ad hoc networks are emerging as a cost-effective, yet, powerful tool for communication. These systems, where networks can emerge and converge on-the-fly, are guided by the forward-looking goals of providing ubiquitous connectivity and constant access to information. Due to power and bandwidth constraints, the vulnerability of the wireless medium, and the multi-hop nature of ad hoc networks, these networks are becoming increasingly complex dynamic systems. Besides, modern radios are empowered to be reconfigurable, which harbors the temptation to exploit the system. To understand the implications of these issues, some of which pose significant challenges to efficient network design, we study topology control using game theory. We develop a game-theoretic framework of topology control that broadly captures the radio parameters, one or more of which can be tuned under the purview of topology control. In this dissertation, we consider two parameters, viz. transmit power and channel, and study the impact of controlling these on the emergent topologies. We first examine the impact of node selfishness on the network connectivity and energy efficiency under two levels of selfishness: (a) nodes cooperate and forward packets for one another, but selfishly minimize transmit power levels and; (b) nodes selectively forward packets and selfishly control transmit powers. In the former case, we characterize all the Nash Equilibria of the game and evaluate the energy efficiency of the induced topologies. We develop a better-response-based dynamic that guarantees convergence to the minimal maximum power topology. We extend our analysis to dynamic networks where nodes have limited knowledge about network connectivity, and examine the tradeoff between network performance and the cost of obtaining knowledge. Due to the high cost of maintaining knowledge in networks that are dynamic, mobility actually helps in information-constrained networks. In the latter case, nodes selfishly adapt their transmit powers to minimize their energy consumption, taking into account partial packet forwarding in the network. This work quantifies the energy efficiency gains obtained by cooperation and corroborates the need for incentivizing nodes to forward packets in decentralized, energy-limited networks. We then examine the impact of selfish behavior on spectral efficiency and interference minimization in multi-channel systems. We develop a distributed channel assignment algorithm to minimize the spectral footprint of a network while establishing an interference-free connected network. In spite of selfish channel selections, the network spectrum utilization is shown to be within 12% of the minimum on average. We then extend the analysis to dynamic networks where nodes have incomplete network state knowledge, and quantify the price of ignorance. Under the limitations on the number of available channels and radio interfaces, we analyze the channel assignment game with respect to interference minimization and network connectivity goals. By quantifying the interference in multi-channel networks, we illuminate the interference reduction that can be achieved by utilizing orthogonal channels and by distributing interference over multiple channels. In spite of the non-cooperative behavior of nodes, we observe that the selfish channel selection algorithm achieves load balancing. Distributing the network control to autonomous agents leaves open the possibility that nodes can act selfishly and the overall system is compromised. We advance the need for considering selfish behavior from the outset, during protocol design. To overcome the effects of selfishness, we show that the performance of a non-cooperative network can be enhanced by appropriately incentivizing selfish nodes.
Ph. D.

In recent years, Software Defined and Cognitive Radios (SDRs and CRs) have become popular topics of research. Game theory has proven to be a useful set of tools for analyzing wireless networks, including Cognitive Networks (CNs). This thesis provides a game theoretic cross-layer mechanism that can be used to control SDRs and CRs. We have constructed an upper-layer Topology Control (TC) game, which decides which links each node uses. A TDMA algorithm which we have adapted is then run on these links. The links and the TDMA schedule are then passed to a lower-layer game, the Link Adaptation Game (LAG), where nodes adjust their transmit power and their link parameters, which in this case are modulation scheme and channel coding rate. It is shown that both the TC game and the LAG converge to a Nash Equilibrium (NE). It is also shown that the solution for the TC game approximates the topology that results from maximizing the utility function when appropriate link costs are used. Also seen is the increase in throughput provided by the LAG when compared to the results of Greedy Rate Packing (GRP).
Master of Science

Emotional Stroop task results have been shown to be inconsistent throughout the literature due to a multitude of factors including both stimulus and population factors. There are also several theories to explain the emotional Stroop effects, including the attentional control theory (Eysenck et al., 2007). This theory states that anxiety consumes attentional and memory resources, resulting in impairment in executive functions, and thus cognitive performance is lowered. Recently, Owens et al. (2014) reported that the effects of anxiety on cognitive performance might be moderated by working memory capacity (WMC). The present study explored whether Owens et al.'s (2014) paradigm fit the Stroop data. It also explored the role that WMC had in recognition memory for emotional and neutral words. Processing efficiency during the Stroop task and anxiety was expected to show a positive relationship for High WMC and a negative relationship for Low WMC. Furthermore, memory for emotional words were expected to be better for Low WMC due to longer processing times for emotional words. The results showed that WMC did not improve the model for both the emotional Stroop and the surprise recognition memory task, thereby contradicting Owens et al.'s (2014) proposed paradigm. Furthermore, an increase of anxiety scores showed a decrease in memory for emotional words but only for Low WMC.

The usage of the wireless communication technologies have been increasing due to the benefits they provide in our daily life. These technologies are used in various fields such as military communication, public safety, cellular communication. The current systems might not be sufficient to meet the increasing demand. Therefore, the new solutions such as the usage of smart antennas have been proposed to satisfy this demand. Among different solutions, cognitive heterogeneous networks (HetNets) have been recently introduced as a promising one to meet the high user demand. In cognitive Hetnets, there are secondary base stations (SBSs) with secondary users (SUs) and primary base stations (PBSs) with primary users (PUs) in a given area without any coordination between SBS-SBS and SBS-PBS. Due to the physical coexistence of SBSs and the lack of available spectrum, interference caused by the SBSs becomes a significant issue. Therefore, there is a need for the techniques that allow users to share the same spectrum while maintaining the required performance level for each user by adopting interference mitigation techniques. In this dissertation, we focus on resource allocation, interference coordination/mitigation and channel control techniques in 4G and beyond systems. As resource allocation techniques, we propose two studies. In the first study, we present the random subcarrier selection algorithm which is that each SU selects a specific number of subcarriers determined by its needs. In comparison where, at each iteration of the game, the SU searches all the subcarriers to maximize its payof, our algorithm is based on selecting the subcarriers randomly and checks only those subcarriers that achieve higher payof. In the second study, we utilize the reconfigurable antennas (RAs) which allows wireless devices to alter their antenna states determined by different radiation patterns to maximize received signal strength, and present the joint subcarrier and antenna state selection algorithm. SU selects the subcarriers whose capacity values are the highest among the available ones. Since SUs employ RAs, i.e., multiple antenna states, they obtain the reports for all subcarriers from each antenna states, and select the state with the subcarriers which provide the highest capacity gain. As interference coordination/mitigation technique, we propose a game theoretical partially overlapping filtered multitone (POFMT) scheme. Partially overlapping is performed in both frequency and space domains. While intentional carrier frequency shift is introduced in frequency, RAs are utilized to achieve partially overlapping in space domain. Within a game theoretical framework, when SUs search for the frequency shift ratio, they also select the antenna state to increase the system utility. We also combine the resource allocation technique with POTs and present the game theoretical resource allocation with POFMT. To achieve the resource allocation, an SBS slides a group of consecutive subcarriers through all available ones and computes the utility for each selected subcarriers. It picks the consecutive ones which give the highest capacity result. Our results show that our algorithms reach Nash equilibrium and increase the system gain substantially in terms of the corresponding utility. As channel control technique, we propose a wireless channel control using spatially adaptive antenna arrays. This technique simultaneously utilizes beam-steering and spatial adaptation to enhance the wireless channel gain and system capacity. While the interference is reduced via beam-steering feature of proposed antenna, the wireless channel can be controlled by spatially moving the antenna in one axis. Simulated realized gain patterns at various array positions and phase shifter states are subsequently utilized in link and system level simulations to demonstrate the advantages of the proposed concept. It is shown that the system gain can be increased with the spatial adaptation capability of the antenna.

Dieting and non-dieting are two contrasting approaches to the management of overweight/obesity, but less is known about why people follow non-dieting approaches and how these approaches are associated with health and nutrition status indicators. This thesis enables a greater understanding of why dieting and non-dieting approaches are adopted and provides insight into whether one approach is more favourably associated with nutrition and health status indicators. The findings of this thesis will be useful for clinicians who wish to encourage dieting or non-dieting approaches in their clients and for researchers wishing to understand how best to address overweight and obesity.

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The aim of this study was to test the effectiveness of a new method for treating stress, designated stress control training for children (known locally as TCS-I) in the reduction of the symptomatology of stress in children between 8 and 9 years of age. The TCS-I was composed of 16 weekly meetings lasting 90 minutes each, in group session, and was based on cognitive behavior theory. The participants consisted of 20 children equally divided into two groups: the GTCSI which received the TCS-I training and the GC (control group) who had 16 weekly sessions with a psychologist, which did not involve stress control. Initial testing evaluated the symptomatology of stress, the stressors which the children would normally encounter in their everyday lives and what were the confrontation strategies they used. Using the quadriphase model as a theoretical benchmark which emphasizes four phases in the stress process, namely alert, resistance, near-exhaustion and exhaustion, results show that 60% of children were in the near-exhaustion phase, with a prevalence of psychological reactions. The stressors most mentioned by the children were internal in nature, and related to feelings of anxiety and situations related to impaired self-esteem. It was also found that they made use of numbers and types of strategies that were not sufficient to control their levels of tension. The two groups were compared before and after the GTCSI sessions. Initially, the groups showed no significant differences in terms of the level and phase of stress they were facing. After intervention, it was noted that the GTCSI showed a significant reduction in their level of stress when compared to the control group. It was concluded that stressed children, when subjected to stress control training specific to their needs, are capable of developing confrontation skills and achieving a reduction in levels of stress. It was also concluded that TCS-I is very effective in reducing stress in children and the internal sources of this stress.
Este estudo objetivou testar a efic?cia de um m?todo novo de tratamento do stress, designado treino psicol?gico de stress infantil (TCS-I) na redu??o da sintomatologia do stress em crian?as de 08 anos a 09 anos anos de idade. O TCS-I se constituiu de 16 encontros semanais de 90 minutos de dura??o, em grupo, e se baseou na teoria cognitivo-comportamental. Os participantes foram 20 crian?as distribu?das igualmente em dois grupos: GTCSI que recebeu o TCS-I e outro (grupo comparativo GC) que teve 16 encontros semanais com a psic?loga, n?o direcionados ao controle do stress. A testagem inicial avaliou a sintomatologia de stress, os estressores com os quais as crian?as se deparavam no dia a dia e quais estrat?gias de enfrentamento elas utilizavam. Considerando-se como referencial te?rico o modelo quadrif?sico que enfatiza quatro fases no processo do stress: alerta, resist?ncia, quase exaust?o e exaust?o, os resultados indicam que 60% das crian?as encontravam-se na fase de quase exaust?o, com preval?ncia de rea??es psicol?gicas. Os estressores mais mencionados por elas eram de natureza interna e se referiam a sentimentos de ansiedade e situa??es referentes a uma autoestima prejudicada. Verificou-se ainda que faziam uso de um n?mero e tipo de estrat?gias que se mostrou insuficiente no controle de seus n?veis de tens?o. Os dois grupos foram comparados antes e ap?s a interven??o do GTCSI. No inicio, os grupos n?o mostraram diferen?as significativas quanto ao n?vel e fase do stress na qual se encontravam. Ap?s a interven??o, observou-se, que o GTCSI apresentou uma redu??o significativa no seu n?vel de stress quando comparado ao GC. Concluiu-se que as crian?as estressadas quando submetidas a um treino de controle de stress espec?fico ?s suas necessidades, s?o capazes de desenvolver habilidades de enfrentamento obtendo redu??o nos n?veis de stress. Concluiu-se tamb?m que o TCS-I ? muito eficaz na redu??o do stress infantil e das fontes internas de stress.

It is suggested that neuroticism impairs cognitive performance mostly in difficult tasks i.e. WM tasks, but not so much in easier tasks. However, behavioural, and functional neuroanatomical correlates of detrimental effect of neuroticism in relation to central executive system (CES) during cognitive tasks particularly in multitasking still unknown. I aim at investigating behavioural and functional neuroanatomical correlates of single- and dual-task performance in high and low neurotics. The general hypothesis is that high neurotics will show a poorer performance on processing of cognitive tasks as compared to low neurotics. From a screened population, I select low neurotics (below 6) and high neurotics (over 16) on 24 item Eysenck Personality Questionnaire (EPQ) neuroticism scale. First empirical study was consisted of three standard WM tests. The result of this study showed that high neurotics had lower performance when the task heavily requires CES such as switching and inhibition. Next empirical studies were consisted of dual tasks based on PRP paradigm. In dual task studies, in addition to SOA manipulation SOA (0 and1000ms), task demand manipulated either by presentation of task order or task set maintenance. The results show that high neurotics considerably slower when SOA is short. Further, it has been observed dual task cost differences between high and low neurotics increase as the demand increase either by random tasks or task set maintenance as evident by lower processing efficiency in high neurotics. Also, high neurotics perceived higher stress level as the task demand increase. In the final study, I assessed brain activity by means of functional magnetic resonance imaging (fMRI) in low and high neurotics while they were performing a demanding dual-task and the less demanding component tasks as single-tasks. Imaging data showed that high neurotics showed less dual-task specific activation in lateral and medial prefrontal cortices. In conclusion, I conclude that high levels of neuroticism impair behavioural performance in demanding tasks with higher perceived stress level, and that this impairment is accompanied by reduced activation of the task-associated brain areas. Key words: Neuroticism, Personality, Multitasking, dual-task performance, prefrontal cortex attentional control theory, working memory.

Abstract Medium access control (MAC) in wireless ad hoc networks has received considerable attention for almost a couple of decades; however, there are still open problems which deserve thorough study in order to facilitate migration to the next generation broadband wireless communication systems. In ad hoc networks, a detected frame collision can be due to the so-called unreachability problem, where the destination station is situated either in the transmission or interference range of an emitting station and is unable to receive connection establishment frames from any of its neighboring stations. Unreachability might also be due to the inability of a radio station to respond to any connection establishment request, though when the unreachable station receives the connection establishment requests, however, it is prohibited from responding to the requests due to being situated in the interference range of the emitting neighbor. To investigate the impact of this problem, we have to be equipped with a proper analytical framework; therefore, as the first part of this thesis, a scalable framework called Parallel Space – Time Markov chain (PSTMC) is proposed, through which a finite load non-saturated ad hoc network can be easily modeled. At the first step, a single-hop ad hoc network is considered and the accuracy of the model is evaluated using extensive numerical results. Subsequently, the proposed framework is further extended to model multi-hop ad hoc networks. Several discussions are also given on how the framework can be deployed for an arbitrary network topology. One of the main key features of the PSTMC model is its remarkable scalability in modeling complex network configurations. In fact, it is shown that multi-hop ad hoc networks have bounded complexity in being modeled by the PSTMC framework due to its spectacular specifications. These features lead us to a powerful tool by which an arbitrary network topology can be studied. In addition, the proposed models clearly facilitate demonstrating the impact of the unreachability problem on the performance of multi-hop networks. The introduced framework shows how the unreachability problem degrades the achieved throughput and channel capacity by the contending radio stations depending on the deployed network topology. In the remainder of the thesis the unreachability problem in mobile ad hoc networks is tackled and a new MAC protocol to enhance the performance of the network is proposed. This MAC scheme is equipped with smart decision-making algorithms as well as adaptive management mechanisms to reduce the impact of the unreachability problem in single channel scenarios. Subsequently, the problem of concurrent radio resource management and contention resolution in multi-channel cognitive ad hoc networks is considered. In particular, a multi-channel technique for traffic distribution among a set of data channels without centralized control, which is enabled by a probabilistic channel selection algorithm as well as a multi-channel binary exponential backoff mechanism, is proposed. It is shown through simulations that the suggested scheme outperforms the existing MAC protocols in multi-channel environments as well as cognitive networks coexisting with primary users. A mathematical model is also introduced to study the performance of the multi-channel MAC protocol in a single-hop non-saturated wireless network.

The proliferation of information systems (IS) over the past decades has increased the demand for system authentication. While the majority of system authentications are password-based, it is well documented that passwords have significant limitations. To address this issue, companies have been placing increased requirements on the user to ensure their passwords are more complex and consequently stronger. In addition to meeting a certain complexity threshold, the password must also be changed on a regular basis. As the cognitive load increases on the employees using complex passwords and changing them often, they may have difficulty recalling their passwords. As such, the focus of this experimental study was to determine the effects of raising the cognitive load of the authentication strength for users upon accessing a system via increased strength for passwords requirements. This experimental research uncovered the point at which raising the authentication strength for passwords becomes counterproductive by its impact on end-user performances. To investigate the effects of changing the cognitive load (via different password strength) over time, a quasi-experiment was proposed. Data was collected in an effort to analyze the number of failed operating system (OS) logon attempts, users’ average logon times, average task completion times, and number of requests for assistance (unlock & reset account). Data was also collected for the above relationships when controlled for computer experience, age, and gender. This quasi-experiment included two experimental groups (Group A & B), and a control group (Group C). There was a total of 72 participants from the three groups. Additionally, a pretest-posttest experiment survey was administered before and after the quasi-experiment. Such assessment was done in an effort to see if user’s perceptions of password use would be changed by participating in this experimental study. The results indicated a significant difference between the user’s perceptions about passwords before and after the quasi-experiment. The Multivariate Analysis of Variance (MANOVA) and Multivariate Analysis of Covariate (MANCOVA) tests were conducted. The results revealed a significance difference on the number of failed logon attempts, average logon times, average task completion, and amount of request for assistance between the three groups (two treatment groups & the control group). However, no significant differences were observed when controlling for computer experience, age, and gender. This research study contributed to the body of knowledge and has implications for industry as well as for further study in the information systems domain. It contributed by giving insight into the point at which an increase of the cognitive load (via different password strengths) become counterproductive to the organization by causing an increase in number of failed OS logon attempts, users' average logon times, average task completion times, and number of requests for assistance (unlock and reset account). Future studies may be conducted in the industry as results by differ from college students.

Professional School Counselors (PSCs) are to serve as advocates for all students and promote systemic change (American School Counselor Association, 2008) while navigating complex work environments. The primary purpose of this study was to investigate the contribution of PSCs' social-cognitive development to their levels of ethical and legal knowledge and locus of control orientation. The three constructs and instruments investigated in this study were: (a) social-cognitive development (ego development; the Washington University Sentence Completion Test (WUSCT); Hy & Loevinger 1996), (b) Ethical and Legal Knowledge (the Ethical and Legal Knowledge in Counseling Questionnaire-Revised (ELICQ-R); Lambie, Ieva, Gill, & Hagedorn, 2010), and (c) Locus of Control (the Adult Nowicki-Strickland Internal External Scale- College (ANSIE-C); Nowicki & Duke, 1974; the Work Locus of Control Scale ; Spector, 1988). The findings from this investigation contribute to the school counseling and counselor education literature. The sample size for this study was 301 certified, practicing school counselors (elementary school, middle school, high school, and multi-level) in five states (Colorado, Florida, Maine, Maryland, and New Mexico) across the country. The participants completed data collection packets including a general demographic questionnaire, the WUSCT (Hy & Loevinger 1996), the ANSIE-C (Nowicki & Duke, 1974), the WLCS (Spector, 1988), and the ELICQ-R (Lambie, et al., 2010).; The statistical procedures used to analyze the data included (a) structural equation modeling (path Analysis), (b) simultaneous multiple regression, (c) Pearson product-moment (2-tailed), and (d) Analysis of variance (ANOVA). The primary research hypothesis was that practicing school counselors' social-cognitive development scores would contribute to their locus of control orientation and their levels of ethical and legal knowledge. The statistical analyses identified several significant findings. First, the path analysis model testing the contribution of school counselors' social-cognitive development to locus of control and ethical and legal knowledge did fit for these data. Specifically, the results indicated that school counselors' social-cognitive development contributed to their ethical and legal knowledge (less than 1% of the variance explained) and to locus of control (14% of the variance explained) in the model fit for these data. In addition, locus of control contributed to school counselors' ethical and legal knowledge (2% of the variance explained). Implications for professional school counseling and counselor education are presented, along with areas for future investigation.
ID: 028916565; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 224-249).
Ph.D.
Doctorate
Education

Learner-controlled e-learning has become a preferred medium for the delivery of organizational training. While e-learning offers organizations and trainees many advantages, it also comes with several potential disadvantages. The aim of this study was to explore the relative efficacy of learner- and program-controlled e-learning for content that differs in its complexity. This study also explored cognitive load as a differential mediator of the interaction between learner control and training content complexity for predicting cognitive and behavioral learning outcomes. Finally, learning goal orientation was explored as a motivational individual difference that helps learners cope with complex, learner-controlled e-learning environments. Results suggest that while there is little difference between learners in learner- and program-controlled e-learning environments for content that is relatively simple in nature, complex, learner-controlled e-learning environments are detrimental to cognitive learning relative to complex, program-controlled environments. Moreover, the results suggest that this interaction is differentially mediated by cognitive load, suggesting that complex, learner-controlled environments induce high cognitive demands onto learners which ultimately inhibit cognitive learning. Finally, learning goal orientation was identified as more facilitative individual difference in learner-controlled e-learning environments relative to program-controlled and simple training environments. Theoretical and practical implications of these findings are also discussed.

Cognitive radio is frequently touted as a platform for implementing dynamic distributed radio resource management algorithms. In the envisioned scenarios, radios react to measurements of the network state and change their operation according to some goal driven algorithm. Ideally this flexibility and reactivity yields tremendous gains in performance. However, when the adaptations of the radios also change the network state, an interactive decision process is spawned and once desirable algorithms can lead to catastrophic failures when deployed in a network. This document presents techniques for modeling and analyzing the interactions of cognitive radio for the purpose of improving the design of cognitive radio and distributed radio resource management algorithms with particular interest towards characterizing the algorithms' steady-state, convergence, and stability properties. This is accomplished by combining traditional engineering and nonlinear programming analysis techniques with techniques from game to create a powerful model based approach that permits rapid characterization of a cognitive radio algorithm's properties. Insights gleaned from these models are used to establish novel design guidelines for cognitive radio design and powerful low-complexity cognitive radio algorithms. This research led to the creation of a new model of cognitive radio network behavior, an extensive number of new results related to the convergence, stability, and identification of potential and supermodular games, numerous design guidelines, and several novel algorithms related to power control, dynamic frequency selection, interference avoidance, and network formation. It is believed that by applying the analysis techniques and the design guidelines presented in this document, any wireless engineer will be able to quickly develop cognitive radio and distributed radio resource management algorithms that will significantly improve spectral efficiency and network and device performance while removing the need for significant post-deployment site management.
Ph. D.

Regulatory Focus Theory predicts that the motivation to self-regulate goal-directed thought and behavior depends on two distinct regulation strategies: a promotion focus based on attaining gains and a prevention focus based on avoiding losses. This study took a social-cognitive approach predicting that regulatory focus has an impact on how family startups (several family related founders) explore “new ideas”, exploit “old certainties” and achieve the balance of both (ambidexterity), compared to lone founder startups (only one founder present). It was proposed that the social context of family ties among founders leads them to a prevention focus concerned with avoiding the loss of the socio-emotional benefits of those ties. In order to avoid such a loss, family founders were expected to increase their risk perceptions and thus, explore less than lone founders, who lack such socio-emotional ties. It was also proposed that two commonly used psychological traits in entrepreneurship research --achievement motivation and internal locus of control, predispose entrepreneurs to a promotion focus. Founders with a promotion focus, in turn, were hypothesized to lead startups to more risk-seeking behaviors and to more explorative orientation. The previous argument was used as a springboard to derive hypotheses about ambidexterity (the ability to exploit and explore simultaneously) and survival hazards. Using Regulatory Focus Theory, exploitative orientation, conceptualized as the motivational strength to continue on previous paths of action, was hypothesized to be not significantly different from that of lone founder startups. Taking previous arguments together, lone founder startups were hypothesized to be more ambidextrous than family startups. Finally, ambidexterity and internal locus of control were hypothesized to reduce survival hazards in family startups. The findings suggested that family startups explore less than lone founder startups even after controlling for group effects. Interesting but contradictory findings revealed that internal locus of control have both a positive direct effect and a positive interaction that increases the explorative and ambidextrous orientation gap of family startups over lone founder startups. As expected, ambidexterity and internal locus of control reduced survival hazards on family startups. Implications for practitioners were derived based on a sample of 470 nascent entrepreneurs.

El turismo es uno de los sectores que mayor contribución proporciona al desarrollo económico de un país. Muchos destinos compiten sobre la base de sus imágenes percibidas en relación con otros competidores del mercado. Por lo tanto, es necesario el desarrollo de una imagen positiva de los destinos con el objetivo de lograr una ventaja competitiva real, ya que la imagen de un destino, ya sea para los que lo visitan por primera vez o para los visitantes que repiten, es un término reconocido tanto por académicos y como por los gestores de los destino, como un factor clave en la elección de destino. Internet ha cambiado el comportamiento del consumidor turístico drásticamente. El avance tecnológico y la creciente competencia internacional, afectan por tanto a la manera en que los destinos turísticos son imaginados, percibidos y consumidos. Tal imagen generalmente implica una combinación de componentes cognitivos y afectivos, sobre los cuales se genera una imagen global acerca de un destino específico. Esta imagen puede influir en el posicionamiento del destino y en última instancia, en las intenciones de comportamiento de los turistas, como la futura visita o su recomendación. Por lo tanto, el objetivo principal de esta investigación es contribuir a una mejor comprensión del proceso de formación de la imagen antes de la visita directa al destino por parte del turista. Debido a que el turismo es en gran medida una actividad social, la presente tesis se organiza en torno al modelo de formación de la imagen de destino a través de la teoría de la representación social. Por medio de tres estudios se discuten las fuentes de las representaciones sociales acerca de un destino. Como primera fuente de representación social, en el primer estudio exponemos cómo el contenido generado por otros usuarios sobre un destino es capaz de generar emociones y pensamientos sobre el destino. Los resultados muestran que existe una relación entre las respuestas cognitivas de los individuos y la dimensión cognitiva de la imagen, así como entre las respuestas emocionales expresadas por los individuos y la imagen afectiva del destino. Para los turistas potenciales, el contenido generado por otros usuarios es una importante fuente de información en la formación de una imagen de un destino. Los resultados también confirman que la imagen global es un antecedente importante de las preferencias de un destino. En los dos siguientes estudios, proponemos diferentes estímulos que sirven para evocar la simulación mental del individuo como diferentes fuentes de la representación social. Por un lado, en el segundo estudio, se propone cómo la simulación mental puede ser evocada a través de las imágenes sociales y de las instrucciones sociales a imaginar. El objetivo general era ver si la simulación mental evocada a través de los estímulos mencionados anteriormente, induce a las futuras intenciones de comportamiento de los turistas potenciales. Los resultados muestran que las imágenes sociales y las instrucciones sociales a imaginar estimulan la simulación mental. Dado que la experiencia directa con el destino se considera otra fuente de las representaciones sociales, el tercer estudio fue motivado por la necesidad de comprender mejor el impacto de las variables que contribuyen al uso del mundo virtual desde perspectivas sociales, ya que el individuo no tiene ha tenido todavía la experiencia directa con el destino. Para extender los resultados del estudio anterior, hemos incorporado dos nuevos estímulos que evocan la simulación mental, la presencia social y la viveza en un vídeo promocional de un destino real. Los resultados indican que los usuarios son más propensos a evocar su simulación mental cuando la presencia social y la viveza están presentes en el video promocional. En estos dos últimos estudios hay que destacar el papel mediador de la imagen afectiva. Los resultados demuestran que la simulación mental afecta indirectamente en la imagen cognitiva a través de la imagen afectiva. Por lo tanto, la simulación mental puede ser un importante mediador de la comunicación persuasiva en el contexto de la planificación de viajes. En general, los resultados de los tres estudios ponen de manifiesto la importancia de considerar las fuentes de la representación social como una aproximación para la formación de la imagen del destino.
Tourism is one of the sectors that provide the largest contribution to the economic development of countries. Destinations very much compete based on their perceived images relative to competitors in the marketplace. Therefore, it is of high interest to develop a positive image of the destination in target markets to achieve a real competitive advantage. Destination image, whether that held by first time or by repeat visitors, is recognized by academics and destination managers/marketers as a key factor in destination choice. Internet has changed tourism consumer behavior dramatically. Technological advancement and increased international competition thus affect the way in which tourism destinations are imagined, perceived and consumed. Such an image is generally accepted that involves a combination of cognitive and affective components, upon which an overall image is generated about a specific destination. Therefore, this image can influence destination positioning and ultimately the tourist’s behavioral intentions, as the visit or its recommendation. The main objective of this research was to contribute to a better understanding of image formation process before visiting a tourist destination. But tourism is also very much a social activity, this dissertation is organized around the destination image formation model through the theory of social representation. We discuss about the main the sources of social representations about a destination that we will develop in the following three studies. As a first source of social representation, in the first study we demonstrate how content generated by other users in a web destination is able to generate emotions and thoughts about the destination, and then we explore the role of emotions and thoughts in destination image formation. Our results show that a correspondence exists between cognitions that came into the consumers’ minds and the cognitive dimension of image, as well as between the emotions expressed by subjects and the affective dimension of image. For potential tourists, user generated content (UGC) is an important information source in forming an image towards a particular destination. Results also confirm that the image of a destination was an important predictor of destination preferences. In the following studies, we propose insights into the nature of stimuli that may evoke mental simulation, using different sources of social representation as stimuli. In the second study, we demonstrate how mental simulation can be evoked through the social pictures and social instructions to imagine as a source of social representation. The overarching goal was to determinate whether mental simulation, evoked through the stimuli discussed above, induces future behavioral intentions to potential tourists. Results show that both social pictures and social instructions to imagine do stimulate mental simulation. The direct experience with the destination is usually mentioned as a source of social representation. For that reason, the third study was motivated by a need to better understand the impact of the constructs contributing to virtual world usage from social perspectives, since tourist cannot have a direct experience with the destination before visit. To extend the results of the previous chapter, we incorporated two aspects that may help evoke mental simulation. Social presence and vividness were manipulated using a promotional video. Users are more likely to evoke mental simulation when social voice and high vividness are present in the promotional video. The most interesting findings of these studies regards the mediator role of affective image Results demonstrate that mental simulation affects indirectly on cognitive image through affective image. We have confirmed that mental simulation can be an important mediator of persuasive communication in the context of travel planning. In summary, findings from the three empirical studies described in this doctoral dissertation highlight the importance of considering sources of social representation as a very relevant approach for studying destination image formation.

A National Survey indicated that 1.6 million adolescents in the U.S. were arrested in 2010 and 1.5 million in 2011 for erratic aggressive behaviors, thus showing a decline from the 2.18 million adolescent arrests in 2007. Residential facilities in the state of Pennsylvania offer a group intervention called Aggression Replacement Training (ART) to help adjudicated adolescents regain control of erratic behaviors. The purpose of this study was to examine the extent to which level of group participation in ART and certain demographic factors (age, gender, ethnicity, family socioeconomic status, parental involvement, and education) predict decreased aggression and increased anger control among these youth. Cognitive theory and change theory were used to guide this causal-comparative investigation. The overarching research question was, does a youth's level of ART group participation (i.e., attentive, inattentive, and resistant) result in a subsequent reduction in risk assessment as measured by post Aggression Questionnaire score differences. Data were collected for the period of 2011-2014 from archival records from 5 residential facilities (n = 160) in Pennsylvania and were statistically analyzed. Findings from an analysis of variance indicate that ART group participation predict decreased erratic aggressive behaviors and increased anger control among adolescents. Findings from multiple regression analyses indicate that parental involvement predicts attentive participation level, whereas ART group participation, gender, and parental involvement predicted a reduction in risk assessment. Study findings may assist other treatment facilities and affiliated agencies in the U.S. with developing and implementing effective interventions for youth who exhibit erratic aggressive behaviors.

This study aims at exploring the social, affective and cognitive variables that would be related to the use of the address form usted in Chilean Spanish. Specifically, we refer to the use that can be observed in interactions between Chileans residing in Sweden. A particular aspect of this situation is that, while the majority group almost exclusively use the form that is commonly associated with solidarity (in this case the Swedish pronoun du), the minority group referred to maintains the pronoun that normally is associated with power, distance, formality and politeness: usted. In other words, while the equivalent in Swedish of usted (ni) is seldom used in majority language, the opposite is observed in the minority language object of study. We believe that the motives for the use of usted in this minority context are more complex than they appear to be. Consequently, an alternative hypothesis has been worked out with reference to theories within the area of Social Psychology. On this basis the following main hypothesis was formulated: Individuals representing the minority group in ethnic contact situations tend to increase their identification with the minority group in order to be admitted by and adhere to this group, if they feel that they are rejected by the majority group. The form usted is not the result of a fortuitous situation, nor can it be explained by the fact that it is the normal usage in the native country, but that it fulfils a strategic objective: to mark the affiliation with the minority group. The method has consisted in grouping together and correlating factors pertaining to the environment, the agent and the guest according to the Ecological Triad, the interaction of which contributes to the appearance of the observed behaviour that underlies this study. The statistical analysis enabled us to verify what was put forward in the hypothesis.

Mindreading is the capacity to attribute psychological states to others and to use those attributions to explain, predict, and understand others’ behaviors. In the past thirty years, mindreading has become the topic of substantial interdisciplinary research and theorizing, with philosophers, psychologists and, more recently, neuroscientists, all contributing to the debate about the nature of the neuropsychological mechanisms that constitute the capacity for mindreading. In this thesis I push this debate forward by using recent results from developmental psychology as the basis for critiques of two prominent views of mindreading. First, I argue that the developmental studies provide evidence of infant mindreading and therefore expose a flaw in José Bermúdez’s view that certain forms of mindreading require language possession. Second, I argue that the evidence of infant mindreading can also be used to undermine Alvin Goldman’s version of Simulation Theory.

Making decisions is a dynamic process. Especially when we face a decision between conflicting options, different forces seem to drag our mind from one option to the other one (James, 1890), again and again. This process may last for a long time, sometimes only coming to a decision when we are finally forced to choose, e.g. by an important deadline. Psychology and many other disciplines were interested in how humans make decisions from their beginnings on. Many different influences on decisions were discovered (e.g. Kahneman & Tversky, 1979; Todd & Gigerenzer, 2000). In the face of these advances, it seems odd, that knowledge about the ongoing process of reaching a decision is rare and much of the investigation has focused on the final outcome of choice situations (Townsend & Busemeyer, 1995). A very recent approach, called neuroeconomics, started out to investigate what happens behind the scenes of a final decision. Using modern neuroimaging methods, many neuroeconomists explain decision making in the brain in terms of a hierarchy of different neural modules that work together like a big corporation to finally make the best possible decision (Sanfey, Loewenstein, McClure, & Cohen, 2006). However, the focus on neural modules also limits this approach to a quite static view of decision making and many questions, related to the dynamic aspects of decision making, still remain open: How do we continuously control impulsive or habitual tendencies in our decisions when we pursue long-term goals? How do we shift attention back and forth between (goal) relevant properties of choice options? How do we adjust and readjust our focus of attention to relevant information in order to avoid distraction by irrelevant or misleading information? And how are we influenced by the environmental context when we make decisions? The present work aims to show how an approach based on the concepts of dynamic systems theory could complement the module oriented approach and enhance our knowledge of the processes of decision making. Chapter 2 elaborates the limits of the module oriented approach, with a special focus on decisions under conflict, when we are faced with conflicting information, and introduces the principles of a complementary dynamic approach. Chapter 3 deduces the dynamic hypothesis of this work: ongoing processes interactions at different time scales can explain specific cognitive functions without postulating specialized modules for this function. To approach this hypothesis, chapter 4 will develop a theoretical and empirical framework to study decision making dynamically. The empirical part, building on the empirical framework, starts with chapter 5 presenting an EEG experiment. Chapter 6 presents two mouse tracking experiments, and chapter 7 presents a modelling study, reproducing the empirical data of chapters 5 and 6. The general discussion in chapter 8 summarizes the theoretical and empirical results and discusses possible limitations. Finally, chapter 9 discusses the implications of the dynamic approach to decision making, presents an outlook on future research projects, and closes the work by offering a dynamic picture of the processes behind the stage of a final decision
„Man kann nicht beides haben: Den Rahm und die Butter.“ - „Wer die Wahl hat, hat die Qual.“ Mit diesen Sprichwörtern beklagt der Volksmund, womit das Leben uns immer wieder konfrontiert: wir müssen entscheiden, und oftmals führt uns das in Entscheidungskonflikte. Im Dilemma solcher Konflikte mag es begründet sein, dass das Thema der vorliegenden Arbeit, die Entscheidungsforschung, nicht nur in der Psychologie schon immer eine wichtige Rolle spielte, sondern auch in anderen Disziplinen, wie der Ökonomie, der angewandten Mathematik und der Philosophie. Die langjährigen Bestrebungen, diese unterschiedlichen Fachbereiche zu integrieren (z.B. Kahneman & Tversky, 1979; von Neumann & Morgenstern, 1944; Savage, 1972), münden aktuell in das Forschungsgebiet der Neuroökonomie (Camerer, Loewenstein, & Prelec, 2005; Loewenstein, Rick, & Cohen, 2008; Sanfey, Loewenstein, McClure, & Cohen, 2006). Neuroökonomen nutzen vielfach die Methoden der bildgebenden Hirnforschung, um durch die Lokalisierung der neuronalen Basis hierarchisch gegliederter Module Entscheidungsprozesse zu erklären (z.B. Sanfey et al., 2006; Fellows, 2004). Während die Anwendung bildgebender Methoden Potential birgt (z.B. Harrison, 2008), ist es vor allem der modulorientierte Ansatz, der das Risiko einer zu eingeschränkten Sichtweise auf Entscheidungsprozesse trägt (z.B. Ortmann, 2008; Oullier & Kelso, 2006). Dies zeigt sich zum Beispiel im von der kognitiven Psychologie intensiv erforschten Bereich von Entscheidungen unter Konflikt. Eine zentrale Rolle bei dieser Art von Entscheidungen spielen kognitive Kontrollprozesse, die der Umsetzung zielorientierten Verhaltens (Norman & Shallice, 2000) durch Konfliktlösung und -anpassung dienen. Als Bindeglied dieser beiden Prozesse gilt die Detektion von Entscheidungskonflikten, welche die vorherrschende Conflict Monitoring Theory (Botvinick, Braver, Barch, Carter, & Cohen, 2001) entsprechend dem modulorientiertem Ansatz einem speziellen neuronalen Modul zuordnet, das im anterioren cingulären Cortex lokalisiert ist (Botvinick, Cohen, & Carter, 2004). Die Probleme eines einseitigen modulorientierten Ansatzes verdeutlichen hier unter anderem die widersprüchliche Befundlage (z.B. Mansouri, Tanaka, & Buckley, 2009) und die letztlich weiterhin ungeklärte Frage nach den zugrundeliegenden Prozessen. Die Arbeit hat deshalb zum Ziel, den modulorientierten Ansatz um einen komplementären Ansatz auf Basis der Theorie dynamischer Systeme (Dynamical Systems Theory, DST) zu ergänzen. Aus dem grundlegenden DST-Prinzip der kontinuierlichen (z.B. Spivey, 2007) Interaktion rückgekoppelter Komponenten (z.B. Kelso, 1995; Van Orden, Holden, & Turvey, 2003) wird zunächst die dynamische Hypothese abgeleitet, dass sich Effekte auf verschiedenen Zeitskalen gegenseitig bedingen und einander hervorbringen. Für Entscheidungen unter Konflikt bedeutet dies, dass sich die Prozesse der Konfliktlösung und anpassung durch ihre direkte Interaktion im kognitiven System gegenseitig erzeugen. Zur Überprüfung dieser Hypothese werden innerhalb der Arbeit generelle empirische Strategien entwickelt, welche die Untersuchung von Entscheidungsprozessen auf verschiedenen Zeitskalen ermöglichen. Im empirischen Teil der Arbeit werden sodann zwei dieser Strategien zur Anwendung gebracht, um den Erkenntnisgewinn des dynamischen Ansatzes zu illustrieren. Zunächst wird in einer EEG-Studie eine Frequency-Tagging-Methode (z.B. Müller & Hübner, 2002; Müller, Andersen, & Keil, 2007) auf die Untersuchung der kognitiven Kontrollprozesse in einer Flanker-Aufgabe (Eriksen & Eriksen, 1974) adaptiert. Die neue Kombination einer kontinuierlichen neurophysiologischen Methode und eines klassischen Konflikt-Paradigmas ermöglicht die gleichzeitige Untersuchung kontinuierlicher Veränderungen der Aufmerksamkeit auf relevante und irrelevante Information. Die Ergebnisse der Studie stützen die Hypothese einer direkten Interaktion von Prozessen der Konfliktlösung und -anpassung und stellen bereits einen Widerspruch zur Conflict Monitoring Theory dar. Als weitere empirische Strategie wird in zwei Experimenten die Methode des Maus-Tracking (z.B. Buetti & Kerzel, 2009; Song & Nakayama, 2009; Spivey, Grosjean, & Knoblich, 2005) im Rahmen einer Simon-Aufgabe (Simon, 1969) eingesetzt. Die erneute Kombination einer kontinuierlichen Methode, diesmal auf Reaktionsebene, mit einem klassischen Konflikt-Paradigma erlaubt die Messung von Verhaltenstendenzen im Verlauf des gesamten Entscheidungsprozesses. Mit Hilfe einer neu entwickelten regressionsbasierten Analysemethode werden die Subprozesse einzelner Entscheidungen separiert und Einblicke in die Dynamik von Konfliktlösung und -anpassung gewonnen. Die Ergebnisse zeigen ein komplexes Muster zeitlicher Interaktion zwischen den beiden kognitiven Kontrollprozessen, wobei die Konfliktanpassung zeitlich unabhängig von der Verarbeitung irrelevanter Information ist. Dies steht erneut im Widerspruch zu Annahmen der Conflict Monitoring Theory. Zusammenfassend stützen die empirischen Ergebnisse die dynamische Hypothese der kontinuierlichen Interaktion rückgekoppelter Komponenten und werden im nächsten Schritt in einem dynamisch-konnektionistischen Netzwerkmodell integriert. Als Alternative zum Modell der Conflict Monitoring Theory verzichtet es entsprechend dem dynamischen Ansatz auf ein Conflict Monitoring Modul (Botvinick et al., 2001). Es verfügt stattdessen über Verarbeitungs-Prozesse auf verschiedenen Zeitskalen (Kiebel, Daunizeau, & Friston, 2008) und eine Rückkopplung zwischen der Netzwerkschicht, die der Informationsverarbeitung dient, und jener, die der Zielrepräsentation dient (Gilbert & Shallice, 2002; Cohen & Huston, 1994). Die Ergebnisse der Simulation zeigen, dass das Modell sowohl die klassischen Befunde zur Konfliktlösung und anpassung (z.B. Gratton, Coles, & Donchin, 1992), als auch das in den empirischen Studien gefundene kontinuierliche Datenmuster von Entscheidungsprozessen reproduziert. Die empirischen Befunde und die Ergebnisse der Modellierung bestätigen somit die postulierte dynamische Hypothese, dass sich Effekte auf verschiedenen Zeitskalen gegenseitig bedingen und einander hervorbringen. Dies verdeutlicht den komplementären Wert des dynamischen Ansatzes zum modulorientierten Ansatz, welcher vielfach in der Neuroökonomie verfolgt wird. Der hier entwickelte DST-basierte Ansatz bietet somit sowohl ein komplementäres Denkmodell, welches wie der modulorientierte Ansatz eine Verbindung zwischen den Phänomenen auf neuronaler und Verhaltensebene herstellt, als auch neue empirische Methoden zur dynamischen Erforschung von Entscheidungen. Daraus wird abschließend eine Fokuserweiterung für die zukünftige Forschung abgeleitet: zum einen auf die kontinuierlichen Prozesse, welche zu einer Entscheidung führen, und zum anderen auf die Interaktionsdynamik dieser Prozesse. Die Arbeit schließt mit dem Bild eines Entscheidungsprozesses als einer selbstorganisierten, metastabilen Balance (z.B. Kelso, 1995) bei der Lösung verschiedener Entscheidungsdilemmata (Goschke, 2003)

En la actualidad, la Internet de las Cosas (Internet of Things, IoT) es una tecnología esencial para la próxima generación de sistemas inalámbricos. La conectividad es la base de IoT, y el tipo de acceso requerido dependerá de la naturaleza de la aplicación. Uno de los principales facilitadores del entorno IoT es la comunicación machine-to-machine (M2M) y, en particular, su enorme potencial para ofrecer conectividad ubicua entre dispositivos inteligentes. Las redes celulares son la elección natural para las aplicaciones emergentes de IoT y M2M. Un desafío importante en las redes celulares es conseguir que la red sea capaz de manejar escenarios de acceso masivo en los que numerosos dispositivos utilizan comunicaciones M2M. Por otro lado, los sistemas celulares han experimentado un tremendo desarrollo en las últimas décadas: incorporan tecnología sofisticada y nuevos algoritmos para ofrecer una amplia gama de servicios. El modelado y análisis del rendimiento de estas redes multiservicio es también una tarea desafiante que podría requerir un gran esfuerzo computacional. Para abordar los desafíos anteriores, nos centramos en primer lugar en el diseño y la evaluación de las prestaciones de nuevos mecanismos de control de acceso para hacer frente a las comunicaciones masivas M2M en redes celulares. Posteriormente nos ocupamos de la evaluación de prestaciones de redes multiservicio y proponemos una nueva técnica analítica que ofrece precisión y eficiencia computacional. Nuestro principal objetivo es proporcionar soluciones para aliviar la congestión en la red de acceso radio cuando un gran número de dispositivos M2M intentan conectarse a la red. Consideramos los siguientes tipos de escenarios: (i) los dispositivos M2M se conectan directamente a las estaciones base celulares, y (ii) forman grupos y los datos se envían a concentradores de tráfico (gateways) que les proporcionan acceso a la infraestructura. En el primer escenario, dado que el número de dispositivos añadidos a la red aumenta continuamente, esta debería ser capaz de manejar el considerable incremento en las solicitudes de acceso. El 3rd Generation Partnership Project (3GPP) ha propuesto el access class barring (ACB) como una solución práctica para el control de congestión en la red de acceso radio y la red troncal. El ajuste correcto de los parámetros de ACB de acuerdo con la intensidad del tráfico es crítico, pero cómo hacerlo de forma dinámica y autónoma es un problema complejo cuya solución no está recogida en las especificaciones del 3GPP. Esta tesis doctoral contribuye al análisis del rendimiento y al diseño de nuevos algoritmos que implementen efectivamente este mecanismo, y así superar los desafíos introducidos por las comunicaciones masivas M2M. En el segundo escenario, dado que la heterogeneidad de los dispositivos IoT y las arquitecturas celulares basadas en hardware imponen desafíos aún mayores para permitir una comunicación flexible y eficiente en los sistemas inalámbricos 5G, esta tesis doctoral también contribuye al diseño de software-defined gateways (SD-GWs) en una nueva arquitectura propuesta para redes inalámbricas definidas por software que se denomina SoftAir. Esto permite manejar tanto un gran número de dispositivos como el volumen de datos que estarán vertiendo en la red. Otra contribución de esta tesis doctoral es la propuesta de una técnica novedosa para el análisis de prestaciones de redes multiservicio de alta capacidad que se basa en un nuevo enfoque del modelizado analítico de sistemas que operan a diferentes escalas temporales. Este enfoque utiliza el análisis del transitorio de una serie de subcadenas absorbentes y lo denominamos absorbing Markov chain approximation (AMCA). Nuestros resultados muestran que para un coste computacional dado, AMCA calcula los parámetros de prestaciones habituales de un sistema con mayor precisión, en comparación con los resultados obtenidos por otr
Nowadays, Internet of Things (IoT) is an essential technology for the upcoming generation of wireless systems. Connectivity is the foundation for IoT, and the type of access required will depend on the nature of the application. One of the leading facilitators of the IoT environment is machine-to-machine (M2M) communication, and particularly, its tremendous potential to offer ubiquitous connectivity among intelligent devices. Cellular networks are the natural choice for emerging IoT and M2M applications. A major challenge in cellular networks is to make the network capable of handling massive access scenarios in which myriad devices deploy M2M communications. On the other hand, cellular systems have seen a tremendous development in recent decades; they incorporate sophisticated technology and algorithms to offer a broad range of services. The modeling and performance analysis of these large multi-service networks is also a challenging task that might require high computational effort. To address the above challenges, we first concentrate on the design and performance evaluation of novel access control schemes to deal with massive M2M communications. Then, we focus on the performance evaluation of large multi-service networks and propose a novel analytical technique that features accuracy and computational efficiency. Our main objective is to provide solutions to ease the congestion in the radio access or core network when massive M2M devices try to connect to the network. We consider the following two types of scenarios: (i) massive M2M devices connect directly to cellular base stations, and (ii) they form clusters and the data is forwarded to gateways that provide them with access to the infrastructure. In the first scenario, as the number of devices added to the network is constantly increasing, the network should handle the considerable increment in access requests. Access class barring (ACB) is proposed by the 3rd Generation Partnership Project (3GPP) as a practical congestion control solution in the radio access and core network. The proper tuning of the ACB parameters according to the traffic intensity is critical, but how to do so dynamically and autonomously is a challenging task that has not been specified. Thus, this dissertation contributes to the performance analysis and optimal design of novel algorithms to implement effectively this barring scheme and overcome the challenges introduced by massive M2M communications. In the second scenario, since the heterogeneity of IoT devices and the hardware-based cellular architectures impose even greater challenges to enable flexible and efficient communication in 5G wireless systems, this dissertation also contributes to the design of software-defined gateways (SD-GWs) in a new architecture proposed for wireless software-defined networks called SoftAir. The deployment of these SD-GWs represents an alternative solution aiming at handling both a vast number of devices and the volume of data they will be pouring into the network. Another contribution of this dissertation is to propose a novel technique for the performance analysis of large multi-service networks. The underlying complexity of the network, particularly concerning its size and the ample range of configuration options, makes the solution of the analytical models computationally costly. However, a typical characteristic of these networks is that they support multiple types of traffic flows operating at different time-scales. This time-scale separation can be exploited to reduce considerably the computational cost associated to determine the key performance indicators. Thus, we propose a novel analytical modeling approach based on the transient regime analysis, that we name absorbing Markov chain approximation (AMCA). For a given computational cost, AMCA finds common performance indicators with greater accuracy, when compared to the results obtained by other approximate methods proposed in the literature.
En l'actualitat, la Internet de les Coses (Internet of Things, IoT) és una tecnologia essencial per a la propera generació de sistemes sense fil. La connectivitat és la base d'IoT, i el tipus d'accés requerit dependrà de la naturalesa de l'aplicació. Un dels principals facilitadors de l'entorn IoT és la comunicació machine-to-machine (M2M) i, en particular, el seu enorme potencial per oferir connectivitat ubiqua entre dispositius intel · ligents. Les xarxes mòbils són l'elecció natural per a les aplicacions emergents de IoT i M2M. Un desafiament important en les xarxes mòbils que actualment está rebent molta atenció és aconseguir que la xarxa siga capaç de gestionar escenaris d'accés massiu en què una gran quantitat de dispositius utilitzen comunicacions M2M. D'altra banda, els sistemes mòbils han experimentat un gran desenvolupament en les últimes dècades: incorporen tecnologia sofisticada i nous algoritmes per oferir una àmplia gamma de serveis. El modelatge i análisi del rendiment d'aquestes xarxes multiservei és també un desafiament important que podria requerir un gran esforç computacional. Per abordar els desafiaments anteriors, en aquesta tesi doctoral ens centrem en primer lloc en el disseny i l'avaluació de les prestacions de nous mecanismes de control d'accés per fer front a les comunicacions massives M2M en xarxes cel · lulars. Posteriorment ens ocupem de l'avaluació de prestacions de xarxes multiservei i proposem una nova tècnica analítica que ofereix precisió i eficiència computacional. El nostre principal objectiu és proporcionar solucions per a alleujar la congestió a la xarxa d'accés ràdio quan un gran nombre de dispositius M2M intenten connectar-se a la xarxa. Considerem els dos tipus d'escenaris següents: (i) els dispositius M2M es connecten directament a les estacions base cel · lulars, i (ii) formen grups i les dades s'envien a concentradors de trànsit (gateways) que els proporcionen accés a la infraestructura. En el primer escenari, atès que el nombre de dispositius afegits a la xarxa augmenta contínuament, aquesta hauria de ser capaç de gestionar el considerable increment en les sol · licituds d'accés. El 3rd Generation Partnership Project (3GPP) ha proposat l'access class barring (ACB) com una solució pràctica per al control de congestió a la xarxa d'accès ràdio i la xarxa troncal. L'ajust correcte dels paràmetres d'ACB d'acord amb la intensitat del trànsit és crític, però com fer-ho de forma dinàmica i autònoma és un problema complex, la solució del qual no està recollida en les especificacions del 3GPP. Aquesta tesi doctoral contribueix a l'anàlisi del rendiment i al disseny de nous algoritmes que implementen efectivament aquest mecanisme, i així superar els desafiaments introduïts per les comunicacions massives M2M en les xarxes mòbils actuals i futures. En el segon escenari, atès que l'heterogeneïtat dels dispositius IoT i les arquitectures cel · lulars basades en hardware imposen desafiaments encara més grans per permetre una comunicació flexible i eficient en els sistemes sense fil 5G, aquesta tesi doctoral també contribueix al disseny de software-defined gateways (SD-GWS) en una nova arquitectura proposada per a xarxes sense fils definides per programari que s'anomena SoftAir. Això permet gestionar tant un gran nombre de dispositius com el volum de dades que estaran abocant a la xarxa. Una altra contribució d'aquesta tesi doctoral és la proposta d'una tècnica innovadora per a l'anàlisi de prestacions de xarxes multiservei d'alta capacitat que es basa en un nou enfocament del modelitzat analític de sistemes que operen a diferents escales temporals. Aquest enfocament utilitza l'anàlisi del transitori d'una sèrie de subcadenes absorbents i l'anomenem absorbing Markov chain Approximation (AMCA). Els nostres resultats mostren que per a un cost computacional donat, AMCA calcula els paràmetres de prestacions habituals d
Tello Oquendo, LP. (2018). Design and Performance Analysis of Access Control Mechanisms for Massive Machine-to-Machine Communications in Wireless Cellular Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/107946
TESIS

Establishing and maintaining successful communication stands as a critical prerequisite for achieving the goals of inducing and studying advanced computation in small-scale living neuronal networks. The following work establishes a novel and effective method for communicating arbitrary "sensory" input information to cultures of living neurons, living neuronal networks (LNNs), consisting of approximately 20 000 rat cortical neurons plated on microelectrode arrays (MEAs) containing 60 electrodes. The sensory coding algorithm determines a set of effective codes (symbols), comprised of different spatio-temporal patterns of electrical stimulation, to which the LNN consistently produces unique responses to each individual symbol. The algorithm evaluates random sequences of candidate electrical stimulation patterns for evoked-response separability and reliability via a support vector machine (SVM)-based method, and employing the separability results as a fitness metric, a genetic algorithm subsequently constructs subsets of highly separable symbols (input patterns). Sustainable input/output (I/O) bit rates of 16-20 bits per second with a 10% symbol error rate resulted for time periods of approximately ten minutes to over ten hours. To further evaluate the resulting code sets' performance, I used the system to encode approximately ten hours of sinusoidal input into stimulation patterns that the algorithm selected and was able to recover the original signal with a normalized root-mean-square error of 20-30% using only the recorded LNN responses and trained SVM classifiers. Response variations over the course of several hours observed in the results of the sine wave I/O experiment suggest that the LNNs may retain some short-term memory of the previous input sample and undergo neuroplastic changes in the context of repeated stimulation with sensory coding patterns identified by the algorithm.

Le contrôle cognitif est défini comme l'ensemble des processus guidant la sélection de nos actions en fonction de nos buts et des événements externes. Ce travail étudie les bases neurales du contrôle cognitif chez l'humain au moyen de l'imagerie par résonnance magnétique fonctionnelle (IRMf). Dans une première étude, nous montrons qu'il existe trois niveaux hiérarchiques du contrôle cognitif : le contrôle sensoriel, exercé par le cortex prémoteur, sélectionne les actions en fonction des stimuli ; le contrôle contextuel, exercé par le cortex préfrontal latéral (CPFL) postérieur, sélectionne les associations sensorimotrices (les tâches) en fonction du contexte immédiat des stimuli ; le contrôle épisodique, exercé par le CPFL antérieur, sélectionne les tâches et les réponses en fonction des événements passés. Dans une deuxième étude, nous montrons que les contrôles sensoriel, contextuel et épisodique interviennent également dans la sélection préparatoire des actions, et engagent alors respectivement les mêmes régions qui sont engagées au moment de l'exécution. Dans une troisième étude, nous montrons que chaque région du cortex frontal latéral possède une homologue fonctionnelle dans le cortex pariétal. La réciproque n'est toutefois pas vérifiée : nous révélons une région pariétale spécifique qui serait impliquée dans le calcul, et non dans la sélection des réponses possibles associées aux stimuli perçus. En outre, alors que les régions frontales présentent une organisation hiérarchique, les régions pariétales présentent une architecture parallèle. Nos résultats expérimentaux supportent ainsi un modèle global de l'organisation du contrôle cognitif dans le cortex cérébral.

Cette thèse contribue à rendre le marché de la rénovation énergétique durable et autonome. L’objectif est de contribuer à quantifier le risque de non atteinte de la performance énergétique après rénovation. Tout d’abord, nous analysons les facteurs psychologiques des ménages à prendre en compte pour améliorer les modèles de prédictions de consommation d’énergie. Via le programme Je rénove BBC, nous mettons en évidence quatre biais cognitifs impactant l’écart de la consommation d’énergie réelle et prédite. Puis, nous étudions les structures de contrats les plus appropriés pour améliorer le déroulement des chantiers, incitant les artisans à mieux travailler. D’une part, nous déterminons des contrats pour un Agent devant effectuer deux tâches et sous-estimant l’impact de l’une d’entre elles sur la performance du bâtiment. D’autre part, nous testons des incitations individuelles et collectives sur la capacité de plusieurs artisans à se coordonner selon leur formation initiale (DORéMI, …)
This thesis aims at contributing to make the energy renovation market long-lasting and self-sustaining. To achieve this, our objective is to quantify the risk of not achieving energy performance after renovation. First, we analyze households’ psychological factors that should be considered to improve energy consumption prediction models. Drawing on the Je rénove BBC program, we highlight four cognitive biases that negatively impact the difference between actual and predicted energy consumption. We then study the most appropriate contract structures improving the flow and quality of renovation projects, encouraging craftsmen to work better. On one hand, we determine optimal contracts for an Agent who has to perform two tasks and underestimates the impact of one of them on the building's performance. On the other hand, we test individual-based and group-based incentives on the ability of several real Agents (craftsmen) to coordinate, according to their initial training (DORéMI, …)

Objectives: One of the most prominent features of schizophrenia is relatively lower general cognitive ability (GCA). An emerging approach to understanding the roots of variation in GCA relies on network properties of the brain. In this multi-center study, we determined global characteristics of brain networks using graph theory and related these to GCA in healthy controls and individuals with schizophrenia. Methods: Participants (N = 116 controls, 80 patients with schizophrenia) were recruited from four sites. GCA was represented by the first principal component of a large battery of neurocognitive tests. Graph metrics were derived from diffusion-weighted imaging. Results: The global metrics of longer characteristic path length and reduced overall connectivity predicted lower GCA across groups, and group differences were noted for both variables. Measures of clustering, efficiency, and modularity did not differ across groups or predict GCA. Follow-up analyses investigated three topological types of connectivity—connections among high degree “rich club” nodes, “feeder” connections to these rich club nodes, and “local” connections not involving the rich club. Rich club and local connectivity predicted performance across groups. In a subsample (N = 101 controls, 56 patients), a genetic measure reflecting mutation load, based on rare copy number deletions, was associated with longer characteristic path length. Conclusions: Results highlight the importance of characteristic path lengths and rich club connectivity for GCA and provide no evidence for group differences in the relationships between graph metrics and GCA.

ANP
Este trabalho propõe o uso de Mapas Cognitivos Fuzzy Dinâmicos (DFCM, do inglês Dynamic Fuzzy Cognitive Maps), uma evolução dos Mapas Cognitivos Fuzzy (FCM), para o desenvolvimento de sistemas autônomos para tomada de decisões. O FCM representa o conhecimento de forma simbólica, através de conceitos e relações causais dispostas em um grafo. Na sua versão clássica, os FCMs são usados no desenvolvimento de modelos estáticos, sendo inapropriados para o desenvolvimento de modelos temporais ou dinâmicos devido à ocorrência simultânea de todas as causalidades em uma estrutura fixa dos grafos, i.e., os conceitos e suas relações causais são invariantes no tempo. O DFCM utiliza o mesmo formalismo matemático do FCM através de grafos, acrescentando funcionalidades, como por exemplo, a capacidade de auto adaptação através de algoritmos de aprendizagem de máquina e a possibilidade de inclusão de novos tipos de conceitos e relações causais ao modelo FCM clássico. A partir dessas inclusões, é possível construir modelos DFCM para tomada de decisões dinâmicas, as quais são necessárias no desenvolvimento de ferramentas inteligentes em áreas de conhecimento correlatas à engenharia, de modo especifico a construção de modelos aplicados em Robótica Autônoma. Em especial, para as áreas de Robótica de Enxame e Vida artificial, como abordados nesta pesquisa. O sistema autônomo desenvolvido neste trabalho aborda problemas com diferentes objetivos (como desviar de obstáculos, coletar alvos ou alimentos, explorar o ambiente), hierarquizando as ações necessárias para atingi-los, através do uso de uma arquitetura para o planejamento, inspirada no modelo clássico de Subsunção de Brooks, e uma máquina de estados para o gerenciamento das ações. Conceitos de aprendizagem de máquina, em especial Aprendizagem por Reforço, são empregadas no DFCM para a adaptação dinâmica das relações de casualidade, possibilitando o controlador a lidar com eventos não modelados a priori. A validação do controlador DFCM proposto é realizada por meio de experimentos simulados através de aplicações nas áreas supracitadas.
This dissertation proposes the use of Dynamic Fuzzy Cognitive Maps (DFCM), an evolution of Fuzzy Cognitive Maps (FCM), for the development of autonomous system to decision-taking. The FCM represents knowledge in a symbolic way, through concepts and causal relationships disposed in a graph. In its standard form, the FCMs are limited to the development of static models, in other words, classical FCMs are inappropriate for development of temporal or dynamic models due to the simultaneous occurrence of all causalities in a permanent structure, i.e., the concepts and the causal relationships are time-invariant. The DFCM uses the same mathematical formalism of the FCM, adding features to its predecessor, such as self-adaptation by means of machine learning algorithms and the possibility of inclusion of new types of concepts and causal relationships into the classical FCM model. From these inclusions, it is possible to develop DFCM models for dynamic decision-making problems, which are needed to the development of intelligent tools in engineering and other correlated areas, specifically, the construction of autonomous systems applied in Autonomous Robotic. In particular, to the areas of Swarm Robotics and Artificial Life, as approached in this research. The developed autonomous system deals with multi-objective problems (such as deviate from obstacle, collect target or feed, explore the environment), hierarchizing the actions needed to reach them, through the use of an architecture for planning, inspired by the Brook’s classical Subsumption model, and a state machine for the management of the actions. Learning machine algorithms, in particular Reinforcement Learning, are implemented in the DFCM to dynamically tune the causalities, enabling the controller to handle not modelled event a priori. The proposed DFCM model is validated by means of simulated experiments applied in the aforementioned areas.

This dissertation is an attempt at establishing a bridge between biology and physics leading naturally from the field of phase transitions in physics to the cooperative nature of living systems. We show that this aim can be realized by supplementing the current field of evolutionary game theory with a new form of self-organized temporal criticality. In the case of ordinary criticality, the units of a system choosing either cooperation or defection under the influence of the choices done by their nearest neighbors, undergo a significant change of behavior when the intensity of social influence has a critical value. At criticality, the behavior of the individual units is correlated with that of all other units, in addition to the behavior of the nearest neighbors. The spontaneous transition to criticality of this work is realized as follows: the units change their behavior (defection or cooperation) under the social influence of their nearest neighbors and update the intensity of their social influence spontaneously by the feedback they get from the payoffs of the game (environment). If units, which are selfish, get higher benefit with respect to their previous play, they increase their interest to interact with other units and vice versa. Doing this, the behavior of single units and the whole system spontaneously evolve towards criticality, thereby realizing a global behavior favoring cooperation. In the case when the interacting units are oscillators with their own periodicity, homeodynamics concerns, the individual payoff is the synchronization with the nearest neighbors (i.e., lowering the energy of the system), the spontaneous transition to criticality generates fluctuations characterized by the joint action of periodicity and crucial events of the same kind as those revealed by the current analysis of the dynamics of the brain. This result is expected to explain the efficiency of enzyme catalyzers, on the basis of a new non-equilibrium statistical physics. We argue that the results obtained apply to sociological and psychological systems as well as to elementary biological systems.

Emotion research is an important research topic, thus making the measurement of emotion in the workplace crucial. In attempting to study, understand and measure the role of emotions in the human condition, various researchers have identified different theoretical models to manage the information they have gathered and the observations they have made. In order to study or scientifically investigate any human behaviour, it is essential that such behaviour can be measured, if not quantitatively, then at least qualitatively. However, what one finds with regard to emotion research and measurement are two–dimensional models. The existing affect has been described with a choice of two dimensions and structures, i.e. circumplex, positive and negative affect, tense and energetic arousal, and eight combinations of pleasantness and activation. These two dimensions and structures measure a person’s experiences and, thereafter, report them. The question is if these two–dimensional emotion models are sufficient to cover the broad and often complex dynamics of emotions. The start of multiple–emotion dimension models were reported by researchers, who identified a three–dimensional structure in the emotion domain that is suggestive of the Evaluation–Potency– Activation (EPA) dimensions in the connotative or affective meaning of words. However, in recent studies the sufficiency of two–dimension models to comprehensively investigate emotions was questioned. The three–dimensional emotion model was replicated in cross–cultural similarity sorting studies by other researchers. The similarity sorting studies also indicate the importance of studying emotions in specific cultural contexts. Studying emotion in different cultures is especially relevant in a country such as South Africa that has a variety of cultures and eleven official languages. Researchers followed an approach that studied the meaning of emotion in different cultural groups in the context of 144 emotion features using a componential emotion theory approach. Researchers argue in the groundbreaking research that was published in Psychological Science that emotion meaning has more than only two dimensions. The approach postulated by researchers was tested in a student population of three language groups, namely Dutch–, Englishand French–speaking students. According to researchers this is an empirical and theoretical method to study the meaning of emotions across cultures. However, apart from studying the meaning of emotions in specific cultural groups, research also attempts to determine the meaning of emotion in the natural contexts in which they occur. The relevant natural contexts for the field of Industrial Psychology are the work contexts. It is therefore also important to investigate the categories of emotion episodes in the work environment. The general goal of this study was therefore a) to investigate the emotion lexicon in the white Afrikaans–speaking working adult language group, b) to determine the cognitive emotion structure of this cultural group, c) to investigate the meaning of emotion as comprehensively as possible (multidimensional models of the meaning of emotion), and d) to determine the meaning and content of emotion episodes in the workplace. Research Article 1 The research was subsequently presented in two independent phases. Firstly, a free listing of emotion terms was compiled, and secondly the emotion terms were prototypically rated by Afrikaans–speaking people in South Africa. Both of these were then used as measuring instruments. A survey was designed to explore the research objectives utilising availability samples in two studies. The participants in the free–listing (N=70) and in the prototypicality (N=70) study consisted of native Afrikaans–speaking employees. The sample consisted of participants from the white ethnic group speaking Afrikaans within the Eastern Cape, Gauteng, Free State, Mpumalanga, North–West and KZN provinces and use was made of an availability sample. After conducting the research, the emotion terms with the highest frequency, as identified during the first study, the free listing task, were to be happy (gelukkig wees), be sad (hartseer wees), love (liefde), anger (kwaad) and hateful (haatlik). The emotion terms with the lowest scores as identified during the free listing were uncomfortable (ongemaklik), painful (seer), be hurt (seergemaak wees), sympathetic (simpatiek) and shout/yell (skreeu). Correspondingly, the five (5) prototypical terms with the highest scores in Afrikaans were nice (lekker), fed–up/had enough (gatvol/“genoeg gehad”), loveable (liefdevol), anger (kwaad) and to be scared (om bang te wees). The five (5) least prototypical terms from the list generated in the free listing task were: unstable (onvas), bashfulness (skugterheid), captivation (geboeidheid), envy (naywer) and delight (opgetoënheid). From the information obtained in this research it was revealed that the emotion terms nice (lekker), fed up/had enough (gatvol/“genoeg gehad”) and loveable (liefdevol) are at this stage unique to the white Afrikaans language group. These terms had not been reported in any previously conducted prototypical studies. The results of this study contribute to a cross–cultural understanding of the emotion concepts within the Afrikaans–speaking language groups in South Africa. Research Article 2 A survey design was used to achieve the research objectives utilising availability samples in a series of one study. The participants of the Similarity study (N=131) consisted of native Afrikaans–speaking employees. The sample consisted of participants from the white ethnicity group speaking Afrikaans within the Eastern Cape, Gauteng, Free State, Mpumalanga, North– West, KZN and Northern Cape provinces and use was made of an availability sample. Results of Multidimensional Scaling revealed a three–dimensional cognitive emotion structure. The first dimension was the evaluation–pleasantness dimension. This dimension evaluates the pleasantness versus the unpleasantness of an emotion. This dimension is characterised by intrinsic appraisals of pleasantness and goal conduciveness and action tendencies of approach versus avoidance. The second dimension that emerged was a power–control dimension. This dimension is characterised by appraisals of control, how powerful or weak a person feels when a particular emotion is experienced. This includes feelings of dominance or submission, the impulse to act or withdraw and changes in speech and parasymphatic symptoms. The third dimension which emerged was an activation–arousal dimension. According to other researchers this arousal dimension is characterised by sympathetic arousal, e.g. rapid heartbeat and readiness for action. This study produced a cognitive emotion structure in a white Afrikaans–speaking working adult population in South Africa. To add value to the field of Industrial Psychology, the threedimension structure (evaluation–pleasantness, power–control and activation–arousal dimension) that was found, is very important and valuable when studying the meaning of emotion and can consequently be used as a reference for other emotion research constructs. If it is accurate as stated in literature, there are three and not only two emotion dimension structures, and researchers are missing out on a bigger picture for not drawing on the experience of emotion sufficiently. Research Article 3 A survey design and an availability sample (N=120) in the Eastern Cape, Free State and Gauteng provinces in South Africa was utilised for this study. The Meaning Grid was translated and backtranslated and adapted for use in Afrikaans. The Cronbach's alpha coefficients were obtained for the emotion terms. According to the results of the Meaning Grid instrument, the following emotion terms were the highest: disgust (afkeur) 0,95; pleasure (plesier) 0,94; stress (stres) 0,92; happiness (blydskap) 0,91; joy (vreugde) 0,91; fear (bang) 0,91; anger (angstig) 0,91 and hate (haat) 0,90. The emotion terms that scored the lowest with the Meaning Grid instrument were compassion (medelye) 0,79; pride (trots) 0,79 and contempt (minagting) 0,74. Out of the 24 emotion terms of the Meaning Grid instrument, 8 terms were above 0,90 and 13 were between 0,80 and 0,89. Only 3 terms were between 0,74 and 0,79 [compassion (medelye), pride (trots) and contempt (minagting)]. A three–factor solution was found which represented four emotion dimensions (evaluation, arousal/unpredictability and power) that were universal to the emotion structures found in European samples. Factor scores of the 24 Meaning Grid emotions indicate a three–factor solution that explained 62,2 % of the total variance. The first factor was labelled evaluation and explained 43,0% of the variance, the second factor was labelled arousal/unpredictability as it was a combination of arousal and unpredictability and explained 11,0% of the variance, and the third factor was labelled power and explained 8,2% of the variance. This study followed an approach that investigated the meaning structure of emotion in the sample group in the context of 144 emotion features using a componential emotion theory approach. Different researchers argued that emotion meaning has more than only two dimensions. A three–dimensional emotion structure was found that was universal to the emotion structures of three language groups in a European sample. Therefore, the meaning of emotions for this sample group is far more complex than the two–dimensional emotion models that are found in literature. According to the componential emotion theory approach, the 144 emotion features are very important building blocks for Industrial Psychology when studying the meaning of emotion. Research Article 4 A survey design was used in this research study. The Episode Meaning Grid was administered and participants reported on the two intense emotion experiences at work (in total 358 episodes). Employees rated their emotion experiences on features based on the componential emotion theory and also described the emotion events in their own words. The participants in the emotion episodes (N=179) study consisted of native white Afrikaans–speaking working adults. The sample consisted of participants from the white ethnicity group speaking Afrikaans within the Eastern Cape, Free State and North–West provinces and use was made of an availability sample. The results indicated a three–dimensional structure (evaluation–pleasantness, activation–arousal and power–control dimension) was identified within a white Afrikaans–speaking working adult language group. The first dimension was an evaluation–pleasantness dimension. The second dimension was an activation–arousal dimension. The third dimension was a power–control dimension. Regarding the reporting of emotion episodes one hundred and ninety seven respondents reported 84 satisfying emotion episodes and 267 less satisfying emotion episodes that took place at work. Nine different categories of episodes for satisfying emotions experienced were mentioned. It consists of behaviour of work colleagues, acts of boss/superior/management, goal achievement, receiving recognition, workplace policy, task recognition, personal incidents, emotion involvement and subordinate behaviour. The three highest categories of satisfying emotions episodes were “Goal Achievement” (N=31), “Receiving Recognition” (N=20) and “Personal Incidents” (N=10). Goal achievement describes situations where job related targets or goals were met, and receiving recognition refers to positive feedback from managers, supervisors and work colleagues on meeting targets. Nineteen different categories of episodes for less satisfying emotion episodes were mentioned. It consists of behaviour of work colleagues, acts of boss/superior/management, lack of goal achievement, lack of receiving recognition, workplace policy, task requirement, personal incidents, emotional involvement, subordinate behaviour, workload, work mistakes, customer behaviour, external environment, lack of control, physical well–being, involvement in disciplinary action, workplace strikes, wellness of colleagues and unfairness in the workplace. In the categories of less satisfying emotions episodes, the three highest were “Behaviour of Work Colleagues” (N=58), “Acts of Boss/Superior/Management” (N=47) and “Task Requirement” (N=33). The first two categories are appraised less satisfying behaviour towards oneself or others by work colleagues, managers, supervisors and customers. In terms of the categories of satisfying and less satisfying emotions episodes, less satisfying emotion episodes outnumbered satisfying emotions episodes by three to one. By making use of a multi–componential emotion model, the results confirm that the four factors of pleasantness, power, arousal, and unpredictability, in that order of importance, are essential to satisfactorily determine the emotion experience and meaning of emotion terms. A threedimensional emotion structure (evaluation, arousal and power) was found after determining the meaning of emotion in the natural contexts in which they occur. The answer to the question if these two–dimensional emotion models, as stated in literature, are sufficient to cover the broad and often complex dynamics of emotion, is certainly no. Recommendations for the organisation and future research were made.
Thesis (Ph.D. (Industrial Psychology))--North-West University, Potchefstroom Campus, 2012.

Preventing cyberterrorism is becoming a necessity for individuals, organizations, and governments. However, current policies focus on technical and managerial aspects without asking for experts and non-experts values and preferences for preventing cyberterrorism. This study employs value focused thinking and public value forum to bare strategic measures and alternatives for complex policy decisions for preventing cyberterrorism. The strategic measures and alternatives are per socio-technical process.

La problématique de l'apprentissage de comportements sur un robot autonome soulève de nombreuses questions liées au contrôle moteur, à l'encodage du comportement, aux stratégies comportementales et à la sélection de l'action. Utiliser une approche développementale présente un intérêt tout particulier dans le cadre de la robotique autonome. Le comportement du robot repose sur des mécanismes de bas niveau dont les interactions permettent de faire émerger des comportements plus complexes. Le robot ne possède pas d'informations a priori sur ses caractéristiques physiques ou sur l'environnement, il doit apprendre sa propre dynamique sensori-motrice. J'ai débuté ma thèse par l'étude d'un modèle d'imitation bas niveau. Du point de vue du développement, l'imitation est présente dès la naissance et accompagne, sous de multiples formes, le développement du jeune enfant. Elle présente une fonction d'apprentissage et se révèle alors être un atout en terme de temps d'acquisition de comportements, ainsi qu'une fonction de communication participant à l'amorce et au maintien d'interactions non verbales et naturelles. De plus, même s'il n'y a pas de réelle intention d'imiter, l'observation d'un autre agent permet d'extraire suffisamment d'informations pour être capable de reproduire la tâche. Mon travail a donc dans un premier temps consisté à appliquer et tester un modèle développemental qui permet l'émergence de comportements d'imitation de bas niveau sur un robot autonome. Ce modèle est construit comme un homéostat qui tend à équilibrer par l'action ses informations perceptives frustres (détection du mouvement, détection de couleur, informations sur les angles des articulations d'un bras de robot). Ainsi, lorsqu'un humain bouge sa main dans le champ visuel du robot, l'ambigüité de la perception de ce dernier lui fait confondre la main de l'humain avec l'extrémité de son bras. De l'erreur qui en résulte émerge un comportement d'imitation immédiate des gestes de l'humain par action de l'homéostat. Bien sûr, un tel modèle implique que le robot soit capable d'associer au préalable les positions visuelles de son effecteur avec les informations proprioceptives de ses moteurs. Grace au comportement d'imitation, le robot réalise des mouvements qu'il peut ensuite apprendre pour construire des comportements plus complexes. Comment alors passer d'un simple mouvement à un geste plus complexe pouvant impliquer un objet ou un lieu ? Je propose une architecture qui permet à un robot d'apprendre un comportement sous forme de séquences temporelles complexes (avec répétition d'éléments) de mouvements. Deux modèles différents permettant l'apprentissage de séquences ont été développés et testés. Le premier apprend en ligne le timing de séquences temporelles simples. Ce modèle ne permettant pas d'apprendre des séquences complexes, le second modèle testé repose sur les propriétés d'un réservoir de dynamiques, il apprend en ligne des séquences complexes. A l'issue de ces travaux, une architecture apprenant le timing d'une séquence complexe a été proposée. Les tests en simulation et sur robot ont montré la nécessité d'ajouter un mécanisme de resynchronisation permettant de retrouver les bons états cachés pour permettre d'amorcer une séquence complexe par un état intermédiaire. Dans un troisième temps, mes travaux ont consisté à étudier comment deux stratégies sensorimotrices peuvent cohabiter dans le cadre d'une tâche de navigation. La première stratégie encode le comportement à partir d'informations spatiales alors que la seconde utilise des informations temporelles. Les deux architectures ont été testées indépendamment sur une même tâche. Ces deux stratégies ont ensuite été fusionnées et exécutées en parallèle. La fusion des réponses délivrées par les deux stratégies a été réalisée avec l'utilisation de champs de neurones dynamiques. Un mécanisme de "chunking" représentant l'état instantané du robot (le lieu courant avec l'action courante) permet de resynchroniser les dynamiques des séquences temporelles. En parallèle, un certain nombre de problème de programmation et de conception des réseaux de neurones sont apparus. En effet, nos réseaux peuvent compter plusieurs centaines de milliers de neurones. Il devient alors difficile de les exécuter sur une seule unité de calcul. Comment concevoir des architectures neuronales avec des contraintes de répartition de calcul, de communications réseau et de temps réel ? Une autre partie de mon travail a consisté à apporter des outils permettant la modélisation, la communication et l'exécution en temps réel d'architecture distribuées. Pour finir, dans le cadre du projet européen Feelix Growing, j'ai également participé à l'intégration de mes travaux avec ceux du laboratoire LASA de l'EPFL pour l'apprentissage de comportements complexes mêlant la navigation, le geste et l'objet. En conclusion, cette thèse m'a permis de développer à la fois de nouveaux modèles pour l'apprentissage de comportements - dans le temps et dans l'espace, de nouveaux outils pour maîtriser des réseaux de neurones de très grande taille et de discuter à travers les limitations du système actuel, les éléments importants pour un système de sélection de l'action.

abstract: Behavioral health problems such as physical inactivity are among the main causes of mortality around the world. Mobile and wireless health (mHealth) interventions offer the opportunity for applying control engineering concepts in behavioral change settings. Social Cognitive Theory (SCT) is among the most influential theories of health behavior and has been used as the conceptual basis of many behavioral interventions. This dissertation examines adaptive behavioral interventions for physical inactivity problems based on SCT using system identification and control engineering principles. First, a dynamical model of SCT using fluid analogies is developed. The model is used throughout the dissertation to evaluate system identification approaches and to develop control strategies based on Hybrid Model Predictive Control (HMPC). An initial system identification informative experiment is designed to obtain basic insights about the system. Based on the informative experimental results, a second optimized experiment is developed as the solution of a formal constrained optimization problem. The concept of Identification Test Monitoring (ITM) is developed for determining experimental duration and adjustments to the input signals in real time. ITM relies on deterministic signals, such as multisines, and uncertainty regions resulting from frequency domain transfer function estimation that is performed during experimental execution. ITM is motivated by practical considerations in behavioral interventions; however, a generalized approach is presented for broad-based multivariable application settings such as process control. Stopping criteria for the experimental test utilizing ITM are developed using both open-loop and robust control considerations. A closed-loop intensively adaptive intervention for physical activity is proposed relying on a controller formulation based on HMPC. The discrete and logical features of HMPC naturally address the categorical nature of the intervention components that include behavioral goals and reward points. The intervention incorporates online controller reconfiguration to manage the transition between the behavioral initiation and maintenance training stages. Simulation results are presented to illustrate the performance of the system using a model for a hypothetical participant under realistic conditions that include uncertainty. The contributions of this dissertation can ultimately impact novel applications of cyberphysical system in medical applications.
Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2016

Research Doctorate - Doctor of Philosophy (PhD)
For more than two decades, the processes involved in task switching have been extensively investigated and numerous theories proposed attempting to explain task switch phenomena, such as switch costs, preparation effects and residual switch costs (Grange & Houghton, 2014b). A range of experimental paradigms have been employed to demonstrate the key factors that influence performance; from endogenous mechanisms related to cognitive control and executive functioning, through to task priming, interference and decay processes. I begin this thesis by providing an overview of significant task switch theories, paradigms and findings to illustrate the breadth of existing task switch research. Following this, I present a series of experiments that employ distributional analysis to investigate anticipatory preparation and proactive interference effects on task switch performance. The experiments lead to the proposal of a descriptive, activation driven model of performance, which is tested using specific experimental manipulations. The results indicate the importance of design parameters and how these can affect responding based on strategic and structural task switch related processes. Finally, I investigate the Failure to Engage (FTE) account of residual switch costs (De Jong, 2000) and replicate research that challenges this theory (Brown, Lehmann & Poboka, 2006). The results guided an extension of FTE that was tested in a further experiment and shown to be able to accommodate the effects of interval manipulations as well as both task and cue switching. I then apply a new modelling approach to obtain direct estimates of the probability of preparation and conclude that De Jong’s insights about preparation failure provide a tractable framework for understanding many aspects of cognitive control, including explaining aspects of all of the four major task-switching phenomena identified by Monsell (2003).

This study examined mathematics anxiety among elementary teacher candidates, and to what extent it interacted with the modality principle under various degrees of learner-control. The experiment involved a sample of 186 elementary teacher candidates learning from eight versions of a computer program on division with fractions. The eight versions varied in modality of presentation (diagrams with narration, or diagrams with written text), control of pacing (pacing was controlled by either the learner or the system), and control of sequence (sequence was controlled by either the learner or the system). A pre-test, post-test, demographic questionnaire, subjective measure of mental effort, and the Abbreviated Math Anxiety Survey were also administered. This study revealed that mathematics anxiety was significantly positively correlated with mental effort, and significantly negatively correlated with engagement, pre-test and post-test scores. Additionally, a modality x pacing interaction was observed for both high prior knowledge and low mathematics-anxious students. Under system-pacing, the modality effect was observed, and these students achieved higher far transfer scores when learning from the diagrams and narration modality condition. However, under learner-pacing, the modality effect reversed, and high prior knowledge and low mathematics-anxious students performed better on far transfer scores when learning from the diagrams and written text modality condition. Low prior knowledge, and highly mathematics-anxious students performed poorly in all treatment conditions. Additional interactions involving sequence-control, and a four-way interaction involving prior knowledge, modality, sequence-control, and pacing were also uncovered. The results from this study demonstrate that prior knowledge and mathematics anxiety have a complex relationship with the effectiveness of the format of instruction, and the design of instructional materials needs to take into account these individual differences.
Thesis (Master, Education) -- Queen's University, 2008-09-25 19:38:33.9

The primary purpose of the study was to identify relationships among sources of interpersonal influence, putative psychological mediators, and physical activity. The moderation of these relationships by age, body composition, and educational attainment was also evaluated. Responses from 1224 employees were collected through an online survey at a major healthcare facility in central Texas. Structural equation modeling was used to construct the Social Context Scale of Interpersonal Influence and to estimate its ability to explain intention to be physically active and predict physical activity behavior. Invariance testing provided estimates of moderation by age, education, and body composition. Home social context was positively associated with self-efficacy and positive anticipated outcomes and negatively associated with negative anticipated outcomes. Friend social context was positively associated with self-efficacy, positive anticipated outcomes, and intention. Teasing was positively associated with negative anticipated outcomes. Self-efficacy and positive anticipated outcomes were positively associated with intention. Negative anticipated outcomes were negatively associated with intention. The relationship between friend social context and both positive anticipated outcomes and intention was stronger for obese than non-obese respondents. Home social context was more strongly associated with self-efficacy for those with four year degrees than for those without. Self-efficacy was more strongly associated with intention for those with four year degrees than for those without. Self-efficacy predicted subsequent total leisure time physical activity and the relationship was stronger for respondents over 45 years of age than for those younger than 45. The association between self-efficacy and subsequent total leisure time physical activity was also stronger for respondents with a four year degree than for those without. Home and friend social contexts provide potential conduits for post intervention influence on physical activity behavior. The discussion of the benefits of physical activity among friends may encourage overweight and obese individuals considering exercise, especially those with limited physical activity experiences of their own.
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