Academic literature on the topic 'Contextual color cues'

Here we report the results of a brief experiment investigating the role of attention in mediating contextual effects on synesthetic experiences. Specifically, we examine a grapheme–color synesthete for whom the grapheme letter ‘O’ and number ‘0’ are associated with two very different colors. We presented the grapheme ‘0’ in an array of graphemes that provided ambiguous contextual cues, such that the same grapheme could be perceived either as the number ‘0’ or as the letter ‘O’. We find that an attentional cue that draws attention to one or the other of the contexts biases the perceived synesthetic color of the ‘0’ grapheme to that associated with the cued context. This is true even when the physical color of the grapheme corresponds to the un-cued context.

The accuracy of saccades, as maintained by saccade adaptation, has been shown to be context dependent: able to have different amplitude movements to the same retinal displacement dependent on motor contexts such as orbital starting location. There is conflicting evidence as to whether purely visual cues also effect contextual saccade adaptation and, if so, what function this might serve. We tested what visual cues might evoke contextual adaptation. Over 5 experiments, 78 naive subjects made saccades to circularly moving targets, which stepped outward or inward during the saccade depending on target movement direction, speed, or color and shape. To test if the movement or context postsaccade were critical, we stopped the postsaccade target motion ( experiment 4) or neutralized the contexts by equating postsaccade target speed to an intermediate value ( experiment 5). We found contextual adaptation in all conditions except those defined by color and shape. We conclude that some, but not all, visual cues before the saccade are sufficient for contextual adaptation. We conjecture that this visual contextuality functions to allow for different motor states for different coordinated movement patterns, such as coordinated saccade and pursuit motor planning.

Recent studies have reported that human subjects show varying degrees of ability to use contextual cues to recall the motor skills required to compensate for different dynamic external force fields during arm movements. In particular, the subjects showed little or no ability to use color cues to adjust motor outputs in anticipation of the perturbing fields after limited periods of training that were sufficient to learn to compensate for the fields themselves. This is unexpected since humans and monkeys can use color cues to perform a wide range of visuomotor tasks. Here we show that a monkey with extensive practice compensating for viscous fields in an elbow-movement task can use associated color cues to adjust motor output in anticipation of an impending field before physically encountering it.

Several studies have shown that sensory contextual cues can reduce the interference observed during learning of opposing force fields. However, because each study examined a small set of cues, often in a unique paradigm, the relative efficacy of different sensory contextual cues is unclear. In the present study we quantify how seven contextual cues, some investigated previously and some novel, affect the formation and recall of motor memories. Subjects made movements in a velocity-dependent curl field, with direction varying randomly from trial to trial but always associated with a unique contextual cue. Linking field direction to the cursor or background color, or to peripheral visual motion cues, did not reduce interference. In contrast, the orientation of a visual object attached to the hand cursor significantly reduced interference, albeit by a small amount. When the fields were associated with movement in different locations in the workspace, a substantial reduction in interference was observed. We tested whether this reduction in interference was due to the different locations of the visual feedback (targets and cursor) or the movements (proprioceptive). When the fields were associated only with changes in visual display location (movements always made centrally) or only with changes in the movement location (visual feedback always displayed centrally), a substantial reduction in interference was observed. These results show that although some visual cues can lead to the formation and recall of distinct representations in motor memory, changes in spatial visual and proprioceptive states of the movement are far more effective than changes in simple visual contextual cues.

When the head does not move, rapid movements of the eyes called saccades are used to redirect the line of sight. Saccades are defined by a series of metrical and kinematic (evolution of a movement as a function of time) relationships. For example, the amplitude of a saccade made from one visual target to another is roughly 90% of the distance between the initial fixation point (T0) and the peripheral target (T1). However, this stereotypical relationship between saccade amplitude and initial retinal error (T1-T0) may be altered, either increased or decreased, by surreptitiously displacing a visual target during an ongoing saccade. This form of motor learning (called saccadic adaptation) has been described in both humans and monkeys. Recent experiments in humans and monkeys have suggested that internal (proprioceptive) and external (target shape, color, and/or motion) cues may be used to produce context-dependent adaptation. We tested the hypothesis that an external contextual cue (target color) could be used to evoke differential gain (actual saccade/initial retinal error) states in rhesus monkeys. We did not observe differential gain states correlated with target color regardless of whether targets were displaced along the same vector as the primary saccade or perpendicular to it. Furthermore, this observation held true regardless of whether adaptation trials using various colors and intrasaccade target displacements were randomly intermixed or presented in short or long blocks of trials. These results are consistent with hypotheses that state that color cannot be used as a contextual cue and are interpreted in light of previous studies of saccadic adaptation in both humans and monkeys.

Various contextual factors, such as color, modify how emotions are perceived on the face. In particular, the color red enhances categorization of anger on faces. Yet, an open question remains as to whether red facilitates anger categorization uniformly or whether this effect is specific to targets with characteristics already highly associated with anger. The current work examines whether the color red facilitates anger categorization and whether this effect varies as a function of target gender. We found that red facilitates the processing of anger for male faces (Experiment 1) but not for female faces (Experiment 2), likely due to stronger implicit associations between red with anger for male faces (Experiment 3). The findings suggest that cues to emotion (e.g., red cueing anger) are most salient when the meaning of the signal (e.g., threat) matches observer's implicit notions about the target's characteristics (e.g., capability of doing harm; males).

Humans adopt very different head movement strategies for different gaze behaviors, for example, when playing sports versus watching sports on television. Such strategy switching appears to depend on both context and expectation of future gaze positions. Here, we explored the neural mechanisms for such behaviors by training three monkeys to make head-unrestrained gaze shifts toward eccentric radial targets. A randomized color cue provided predictive information about whether that target would be followed by either a return gaze shift to center or another, more eccentric gaze shift, but otherwise animals were allowed to develop their own eye-head coordination strategy. In the first two animals we then stimulated the frontal eye fields (FEF) in conjunction with the color cue, and in the third animal we recorded from neurons in the superior colliculus (SC). Our results show that 1) monkeys can optimize eye-head coordination strategies from trial to trial, based on learned associations between color cues and future gaze sequences, 2) these cue-dependent coordination strategies were preserved in gaze saccades evoked during electrical stimulation of the FEF, and 3) two types of SC responses (the saccade burst and a more prolonged response related to head movement) modulated with these cue-dependent strategies, although only one (the saccade burst) varied in a predictive fashion. These data show that from one moment to the next, the brain can use contextual sensory cues to set up internal “coordination states” that convert fixed cortical gaze commands into the brain stem signals required for predictive head motion.

The abrupt onset of a novel event captures attention away from, and disrupts, ongoing task performance. Less obvious is that intentional task switching compares with novelty-induced behavioral distraction. Here we explore the hypothesis that intentional task switching and attentional capture by a novel distracter both activate a common neural network involved in processing contextual novelty [Barcelo, F., Periáñez, J. A., & Knight, R. T. Think differently: A brain orienting response to task novelty. NeuroReport, 13, 1887–1892, 2002.]. Event-related potentials were recorded in two task-cueing paradigms while 16 subjects sorted cards following either two (color or shape; two-task condition) or three (color, shape, or number; three-task condition) rules of action. Each card was preceded by a familiar tone cueing the subject either to switch or to repeat the previous rule. Novel sound distracters were interspersed in one of two blocks of trials in each condition. Both novel sounds and task-switch cues impaired responses to the following visual target. Novel sounds elicited novelty P3 potentials with their usual peak latency and frontal-central scalp distribution. Familiar tonal switch cues in the three- and two-task conditions elicited brain potentials with a similar latency and morphology as the novelty P3, but with relatively smaller amplitudes over frontal scalp regions. Covariance and principal component analyses revealed a sustained frontal negative potential that was distorting concurrent novelty P3 activity to the tonal switch cues. When this frontal negativity was statistically removed, P3 potentials to novel sounds and task-switch cues showed similar scalp topographies. The degree of activation in the novelty P3 network seemed to be a function of the information (entropy) conveyed by the eliciting stimulus for response selection, over and above its relative novelty, probability of occurrence, task relevance, or feedback value. We conclude that novelty P3 reflects transient activation in a neural network involved in updating task set information for goal-directed action selection and might thus constitute one key element in a central bottleneck for attentional control.

Online disinhibition effect describes the phenomenon where people feel less restrained in an online environment. People are therefore more likely to express thoughts and opinions that they normally would not share in a face-to-face interaction (Suler, 2004). Online disinhibition effect could either be benign or toxic. Students and instructors in an online learning environment often experience toxic disinhibition in several forms, including arguments about grades, emotional outbursts, potential death threat to the instructor, personal attacks, swearing, and heated arguments using upper-case letters (Rose, 2014). Suler (2004) proposed six factors that contribute to the online disinhibition effect. These six factors include dissociative anonymity, invisibility, asynchronicity, solipsistic introjection, dissociative imagination, and minimization of authority. Not all six factors proposed by Suler (2004) have received equal empirical evidence. Also, not all factors are relevant to online learning environments. This study therefore focused on the factor of invisibility and the lack of contextual cues as a result of invisibility. One of the ways to provide contextual cues in a situation that lacks face-to-face interaction is through the usage of color signaling. Color signaling refers to the usage of colored text to convey information (Elliot, 2015; Lemarié, Lorch, Eyrolle & Virbel, 2008). This study looked at the effects of red color signaling, because the color red has been associated with dominance and aggression (Elliot, Maier, Moller, Friedman & Meinhardt, 2007). It is also often associated with some type of warning sign, such as a stop light or a stop sign (Elliot, 2015). The implicit warning and danger conveyed by the color red has been shown to result in inhibited performance, such that participants who were exposed to the color red had lower performance on the subsequent achievement task (Elliot, Maier, Reidman & Meinhardt, 2007; Gnambs, Appel & Batinic, 2010). Similar effects have also been demonstrated in online gaming situations, where red priming messages lowered the amount of negative language usage (Maher, 2016). It is therefore likely that red priming message could also lower any potential toxic disinhibition in an online learning environment. The current study included two experiments that tested the effects of red priming message and black priming message on 1) participants’ expressed sentiment in their open- ended discussion posts, 2) participants’ self-rating of verbal aggressiveness, and 3) the total number of words generated in the open-ended responses. Past studies have shown that red color could inhibit task performance and reduce offensive language, but it is not clear how a red color priming message might affect discussion posts in a simulated online classroom. Similarly, black color has been shown not to inhibit behavior, but it is not clear how a priming message such as “exercise courtesy and professionalism” might affect participants’ behavior in an online discussion post. Results from the study indicated that red priming message caused participants to rate themselves as less verbally aggressive. This was likely due to increased attention to the priming message and the implicit warning conveyed by the color red. There was evidence that red priming message lowered the amount of negative sentiment expressed in the discussion posts. The results approached statistical significance, but it was not significant probably due to the low levels of negative sentiment expressed. Black priming message was found to be ineffective in lowering verbal aggression rating or negative sentiment expression. The findings from the current study have practical implications in the design of online courses. Instructors could use red priming messages as a strategy to promote a less verbally aggressive and negative online discussion environment.

Patients with alcohol use disorders (AUD) have difficulties with certain aspects of higher-order language functions (HOLF) but there is no data on a wide range of these functions in this group. Therefore, the aim of this study was to compare different aspects of HOLF in patients with AUD and healthy controls (HC). A total of 31 patients with AUD and 44 HC took part in the study. We assessed HOLF with the Right Hemisphere Language Battery (RHLB) and measured control variables: depression using the Patient Health Questionnaire (PHQ) as well as the speed of processing and executive functions with the Color Trails Test (CTT). Patients with AUD had lower results on nine RHLB tests. Moreover, AUD patients had higher scores on PHQ and longer reaction times on CTT. The differences in most RHLB results remained significant after co-varying the control variables. Patients with AUD have difficulties with making inferences from the text, understanding the meaning of individual words, metaphorical content, and prosody, which may impede the comprehension and production of discourse in which linguistic elements must be integrated with non-verbal cues and contextual information. These disturbances may impact various spheres of everyday life and negatively influence social, private, and professional functioning.

Dans cette thèse, nous abordons le contrôle moteur du mouvement du coude à travers deux approches expérimentales : une première étude psychophysique a été effectuée chez les sujets humains, et une seconde implique des enregistrements neurophysiologiques chez le singe. Nous avons recensé plusieurs aspects non résolus jusqu’à présent dans l’apprentissage moteur, particulièrement concernant l’interférence survenant lors de l’adaptation à deux ou plusieurs champs de force anti-corrélés. Nous avons conçu un paradigme où des stimuli de couleur aident les sujets à prédire la nature du champ de force externe actuel avant qu’ils ne l’expérimentent physiquement durant des mouvements d’atteinte. Ces connaissances contextuelles faciliteraient l’adaptation à des champs de forces en diminuant l’interférence. Selon le modèle computationnel de l’apprentissage moteur MOSAIC (MOdular Selection And Identification model for Control), les stimuli de couleur aident les sujets à former « un modèle interne » de chaque champ de forces, à s’en rappeler et à faire la transition entre deux champs de force différents, sans interférence. Dans l’expérience psychophysique, quatre groupes de sujets humains ont exécuté des mouvements de flexion/extension du coude contre deux champs de forces. Chaque force visqueuse était associée à une couleur de l’écran de l’ordinateur et les deux forces étaient anti-corrélées : une force résistante (Vr) a été associée à la couleur rouge de l’écran et l’autre, assistante (Va), à la couleur verte de l’écran. Les deux premiers groupes de sujets étaient des groupes témoins : la couleur de l’écran changeait à chaque bloc de 4 essais, tandis que le champ de force ne changeait pas. Les sujets du groupe témoin Va ne rencontraient que la force assistante Va et les sujets du groupe témoin Vr performaient leurs mouvements uniquement contre une force résistante Vr. Ainsi, dans ces deux groupes témoins, les stimuli de couleur n’étaient pas pertinents pour adapter le mouvement et les sujets ne s’adaptaient qu’à une seule force (Va ou Vr). Dans les deux groupes expérimentaux, cependant, les sujets expérimentaient deux champs de forces différents dans les différents blocs d’essais (4 par bloc), associés à ces couleurs. Dans le premier groupe expérimental (groupe « indice certain », IC), la relation entre le champ de force et le stimulus (couleur de l’écran) était constante. La couleur rouge signalait toujours la force Vr tandis que la force Va était signalée par la couleur verte. L’adaptation aux deux forces anti-corrélées pour le groupe IC s’est avérée significative au cours des 10 jours d’entraînement et leurs mouvements étaient presque aussi bien ajustés que ceux des deux groupes témoins qui n’avaient expérimenté qu’une seule des deux forces. De plus, les sujets du groupe IC ont rapidement démontré des changements adaptatifs prédictifs dans leurs sorties motrices à chaque changement de couleur de l’écran, et ceci même durant leur première journée d’entraînement. Ceci démontre qu’ils pouvaient utiliser les stimuli de couleur afin de se rappeler de la commande motrice adéquate. Dans le deuxième groupe expérimental, la couleur de l’écran changeait régulièrement de vert à rouge à chaque transition de blocs d’essais, mais le changement des champs de forces était randomisé par rapport aux changements de couleur (groupe « indice-incertain », II). Ces sujets ont pris plus de temps à s’adapter aux champs de forces que les 3 autres groupes et ne pouvaient pas utiliser les stimuli de couleurs, qui n’étaient pas fiables puisque non systématiquement reliés aux champs de forces, pour faire des changements prédictifs dans leurs sorties motrices. Toutefois, tous les sujets de ce groupe ont développé une stratégie ingénieuse leur permettant d’émettre une réponse motrice « par défaut » afin de palper ou de sentir le type de la force qu’ils allaient rencontrer dans le premier essai de chaque bloc, à chaque changement de couleur. En effet, ils utilisaient la rétroaction proprioceptive liée à la nature du champ de force afin de prédire la sortie motrice appropriée pour les essais qui suivent, jusqu’au prochain changement de couleur d’écran qui signifiait la possibilité de changement de force. Cette stratégie était efficace puisque la force demeurait la même dans chaque bloc, pendant lequel la couleur de l’écran restait inchangée. Cette étude a démontré que les sujets du groupe II étaient capables d’utiliser les stimuli de couleur pour extraire des informations implicites et explicites nécessaires à la réalisation des mouvements, et qu’ils pouvaient utiliser ces informations pour diminuer l’interférence lors de l’adaptation aux forces anti-corrélées. Les résultats de cette première étude nous ont encouragés à étudier les mécanismes permettant aux sujets de se rappeler d’habiletés motrices multiples jumelées à des stimuli contextuels de couleur. Dans le cadre de notre deuxième étude, nos expériences ont été effectuées au niveau neuronal chez le singe. Notre but était alors d’élucider à quel point les neurones du cortex moteur primaire (M1) peuvent contribuer à la compensation d’un large éventail de différentes forces externes durant un mouvement de flexion/extension du coude. Par cette étude, nous avons testé l’hypothèse liée au modèle MOSAIC, selon laquelle il existe plusieurs modules contrôleurs dans le cervelet qui peuvent prédire chaque contexte et produire un signal de sortie motrice approprié pour un nombre restreint de conditions. Selon ce modèle, les neurones de M1 recevraient des entrées de la part de plusieurs contrôleurs cérébelleux spécialisés et montreraient ensuite une modulation appropriée de la réponse pour une large variété de conditions. Nous avons entraîné deux singes à adapter leurs mouvements de flexion/extension du coude dans le cadre de 5 champs de force différents : un champ nul ne présentant aucune perturbation, deux forces visqueuses anti-corrélées (assistante et résistante) qui dépendaient de la vitesse du mouvement et qui ressemblaient à celles utilisées dans notre étude psychophysique chez l’homme, une force élastique résistante qui dépendait de la position de l’articulation du coude et, finalement, un champ viscoélastique comportant une sommation linéaire de la force élastique et de la force visqueuse. Chaque champ de force était couplé à une couleur d’écran de l’ordinateur, donc nous avions un total de 5 couleurs différentes associées chacune à un champ de force (relation fixe). Les singes étaient bien adaptés aux 5 conditions de champs de forces et utilisaient les stimuli contextuels de couleur pour se rappeler de la sortie motrice appropriée au contexte de forces associé à chaque couleur, prédisant ainsi leur sortie motrice avant de sentir les effets du champ de force. Les enregistrements d’EMG ont permis d’éliminer la possibilité de co-contractions sous-tendant ces adaptations, étant donné que le patron des EMG était approprié pour compenser chaque condition de champ de force. En parallèle, les neurones de M1 ont montré des changements systématiques dans leurs activités, sur le plan unitaire et populationnel, dans chaque condition de champ de force, signalant les changements requis dans la direction, l’amplitude et le décours temporel de la sortie de force musculaire nécessaire pour compenser les 5 conditions de champs de force. Les changements dans le patron de réponse pour chaque champ de force étaient assez cohérents entre les divers neurones de M1, ce qui suggère que la plupart des neurones de M1 contribuent à la compensation de toutes les conditions de champs de force, conformément aux prédictions du modèle MOSAIC. Aussi, cette modulation de l’activité neuronale ne supporte pas l’hypothèse d’une organisation fortement modulaire de M1.
In this thesis, we addressed motor control by two experimental approaches: psychophysical studies in human subjects and neurophysiological recordings in non-human primates. We identified unresolved issues concerning interference in motor learning during adaptation of subjects to two or more anti-correlated force fields. We designed paradigms in which arbitrary color stimuli provided contextual cues that allowed subjects to predict the nature of impending external force fields before encountering them physically during arm movements. This contextual knowledge helped to facilitate adaptation to the force fields by reducing this interference. According to one computational model of motor learning (MOdular Selection And Identification model for Control; MOSAIC), the color context cues made it easier for subjects to build “internal models” of each force field, to recall them and to switch between them with minimal interference. In our first experiment, four groups of human subjects performed elbow flexion/extension movements against two anti-correlated viscous force fields. We combined two different colors for the computer monitor background with two forces: resistive (Vr) and assistive (Va). The first two groups were control subjects. In those subjects, the color of the computer monitor changed at regular intervals but the force field remained constant; Vr was presented to the first group while the second group only experienced Va. As a result, the color cues were irrelevant in the two control groups. All control subjects adapted well to the single experienced force field (Vr or Va). In the two experimental groups, in contrast, the anti-correlated force fields and the monitor colors changed repeatedly between short blocks of trials. In the first experimental group (Reliable-cue subjects), there was a consistent relationship between the force and the stimulus (color of the monitor) - the red colour always signalled the resistive force while the green colour always signalled the assistive force. Adaptation to the two anti-correlated forces for the Reliable-cue group was significant during 10 days of training and almost as good as in the Irrelevant-cue groups who only experienced one of the two force fields. Furthermore, the Reliable-cue subjects quickly demonstrated predictive adaptive changes in their motor output whenever the monitor color changed, even during their first day of training, showing that they could use the reliable color context cues to recall the appropriate motor skills. In contrast, the monitor color also changed regularly between red and green in the second experimental group, but the force fields were not consistently associated with the color cue (Unreliable-cue group). These subjects took longer to adapt to the two force fields than the other three groups, and could not use the unreliable color cue change to make predictive changes to their motor output. Nevertheless, all Unreliable-cue subjects developed an ingenious strategy of making a specific “default” arm movement to probe the type of force field they would encounter in the first trial after the monitor color changed and used the proprioceptive feedback about the nature of the field to make appropriate predictive changes to their motor output for the next few trials, until the monitor color changed again, signifying the possibility of a change in force fields. This strategy was effective since the force remained constant in each short block of trials while the monitor color remained unchanged. This showed that the Unreliable-cue subjects were able to extract implicit and explicit information about the structure of the task from the color stimuli and use that knowledge to reduce interference when adapting to anti-correlated forces. The results of this first study encouraged us to advance our understanding of how subjects can recall multiple motor skills coupled to color context stimuli can be recalled, and how this phenomenon can be reflected by the neuronal activity in monkeys. Our aim was to elucidate how neurons of primary motor cortex (M1) can contribute to adaptive compensation for a wide range of different external forces during single-joint elbow flexion/extension movements. At the same time, we aimed to test the hypothesis evoked in the MOSAIC model, whereby multiple controller modules located in the cerebellum may predict each context and produce appropriate adaptive output signals for a small range of task conditions. Also, according to this hypothesis, M1 neurons may receive inputs from many specialized cerebellar controllers and show appropriate response modulations for a wide range of task conditions. We trained two monkeys to adapt their flexion/extension elbow movements against 5 different force-field conditions: null field without any external force disturbance, two anti-correlated viscous forces (assistive and resistive), which depended on movement speed and resembled that used in the human psychophysical study, a resistive elastic force which depended on elbow-joint position and finally, a visco-elastic field that was the linear sum of the elastic and viscous forces field. Each force field was reliably coupled to 5 different computer monitor background colors. The monkeys properly adapted to the 5 different force-field conditions and used the color context cues to recall the corresponding motor skill for the force field associated with each color, so that they could make predictive changes to their motor output before they physically encountered the force fields. EMG recordings eliminated the possibility that a co-contraction strategy was used by the monkeys to adapt to the force fields, since the EMG patterns were appropriate to compensate for each force-field condition. In parallel, M1 neurons showed systematic changes in their activity at the single-neuron and population level in each force-field condition that could signal the required changes in the direction, magnitude and time course of muscle force output required to compensate for the 5 force-field conditions. The patterns of response changes in each force field were consistent enough across M1 neurons to suggest that most M1 neurons contributed to the compensation for all force field conditions, in line with the predictions of the MOSAIC model. Also, these response changes do not support a strongly modular organization for M1.