Academic literature on the topic 'Optimal-Viewing position (OVP)'

Abstract In order to assess the unique reading processes in Arabic, given its unique orthographic nature of natural inherent variations of inter letter spacing, the current study examined the extent and influence of connectedness disparity during single word recognition using the optimal viewing position (OVP) paradigm (three-, four- and five-letter stimuli presented at a normal reading size, at all possible locations). The initial word viewing position was systematically manipulated by shifting words horizontally relative to an imposed initial viewing position. Variations in recognition and processing time were measured as a function of initial viewing position. Fully connected/unconnected Arabic words were used. It was found that OVP effects occurred during the processing of isolated Arabic words. In Arabic, the OVP may be in the center of the word. No OVP was found in three-letter words; for four- and five-letter words, the OVP effect appeared as a U-shaped curve with a minimum towards the second and third letters. Thus, the OVP effects generalize across structurally different alphabetic scripts.

In order to assess the unique reading processes in Arabic, given its unique orthographic nature of natural inherent variations of inter-letter spacing, the current study examined the extent and influence of connectedness disparity during single word recognition using the optimal viewing position (OVP) paradigm. The initial word viewing position was systematically manipulated by shifting words horizontally relative to an imposed initial viewing position. However, unlike previous research, partially connected/unconnected three-, four- and five-letter Arabic words were displayed in the left and right visual hemifields at all possible locations of letter fixation. It was found that OVP effects occurred during the processing of isolated Arabic words. No OVP was found in three-letter words; for four- and five-letter words, the OVP effect appeared as a U-shaped curve with a minimum towards the second and third letters. Thus, the OVP effects generalize across structurally different alphabetic scripts. Furthermore, a perceptual superiority was found for words with right-positioned unconnected sub-units as compared to left positioned unconnected sub-units because of the differential sensitivity of the hemispheres to the gestalt form of letters. Such findings support the established view that the LH specializes in word recognition for alphabetic languages.

Abstract. Coloring only a single letter in the Stroop task can result in a reduction or elimination of Stroop interference. The present experiments were designed to test whether this modulation of Stroop interference occurs at all letter positions. Specifically, we investigated whether Stroop interference was reduced when the colored letter occupied the optimal viewing position (OVP). The experiments show that Stroop interference is not reduced at the OVP (Experiment 1) and that Stroop interference at the OVP is significantly greater than at other letter positions (Experiments 1 and 2). This finding has important theoretical and methodological consequences for studies of automatic processing in visual word recognition.

Abstract The present study provides a further exploration of the role of Arabic letter visibility as a possible cause of the Optimal Viewing Position (OVP) effect. We used isolated connected and un-connected Arabic letters of different shapes (basic, initial, medial, final) placed at the center of fixation (Experiment 1) and at various possible positions in isolated presentation (Experiment 2). In order to investigate whether performance in the visual identification task is modulated by letter type, we presented each of the isolated connected and un-connected letter targets in each of the eleven stimulus positions across the array to produce a mean RT (ms) for each of the letter types. Using the initial fixation paradigm enabled us to compare reaction times with correctly identified letter targets appearing in the different possible positions. The findings of the present experiments demonstrated that visual letter recognition is influenced by: (i) the isolated letters’ type (connected, un-connected), as connected letters are easier to recognize than un-connected letters; (ii) isolated letters’ shape (basic, initial, medial, final), as medial and final are harder to recognize than basic and initial letter shapes; (iii) visual field, as reading rates were longer for letter stimuli that were presented in LVF compared to RVF; and (iv) eccentricity, as letter reading rates were correlated with their eccentric placement.

La fovéa est la seule zone de la rétine où l’acuité visuelle est maximale. Les mécanismes qui visent à déterminer à quels endroits vont avoir lieu les prochaines fixations restent débattus. Certains auteurs suggèrent que les yeux sont principalement attirés par les zones les plus saillantes de la scène. D’autres suggèrent qu’ils sont orientés vers les objets. Les propriétés du système oculomoteur contraignent également les mouvements oculaires. L’objectif de cette thèse était de départager ces différents points de vue en examinant la contribution respective et le décours temporel des facteurs visuo-moteurs de bas niveau et des facteurs cognitifs de plus haut niveau dans la détermination des mouvements oculaires. Nous nous sommes focalisés sur trois phénomènes comportementaux clés : la tendance à bouger les yeux à proximité du centre des objets (Prefered-Viewing Location), les répercussions qu’ont ces positions d’atterrissage sur les durées initiales des fixations (Inverted Optimal-Viewing-Position) et les probabilités de refixation (Optimal-Viewing-Position). Nous avons observé que ces trois effets émergeaient, et ce, quel que soit le type de stimulus testé: des objets, des mots ou des objets sans signification. Cela suggère que ces effets reflètent les propriétés de bas niveau des systèmes visuel et oculomoteur. Par ailleurs, nous avons observé que l’endroit où les yeux atterrissaient au sein de l’objet était également influencé au fil du temps par les traitements de plus haut-niveau des propriétés du stimulus. Les saccades initiées plus tardivement atterrissaient plus proches de la zone la plus informative de l’objet
High-quality vision is restricted to the fovea - a small region at the center of gaze. The mechanisms that determine which locations in a scene are selected for fixation remain debated. Some suggest that eye movements are mainly driven by the salient features in a scene. Others suggest that eye guidance is object based. The properties of the oculomotor system also strongly constrain eye behavior, but these have been neglected in most existing models. The purpose of this thesis was to disentangle between these different views, by investigating how low-level visuomotor factors versus higher-level cognitive factors contribute to eye movements towards and within isolated objects, and with which time course. We focused on three viewing-position effects: the tendency to move the eyes near the centers of objects (the PVL effect), and the repercussions these initial landing positions have on initial fixation durations (the I-OVP effect) and refixation probabilities (the OVP effect). We found that these three viewing-position effects emerged, and were comparable, in all stimulus types that we tested in this thesis: objects, words and even meaningless non-objects. This suggests that the effects reflect low-level properties of the visual and oculomotor systems. Furthermore, we found that where the eye moved within objects became influenced by ongoing processing of higher-level stimulus properties (e.g., object affordances) over time. Later- compared to early-triggered initial saccades, and even more so within-object refixations, were biased towards the most informative part of the objects, and away from their center of gravity