Atypical visual behaviour has been recently proposed to account for much of social misunderstanding in autism. Using an eye-tracking system and a gaze-contingent lens display, the present study explores self-monitoring of eye motion in two conditions: free visual exploration and guided exploration via blurring the visual field except for the focal area of vision. During these conditions, thirteen students with High Functioning Autism Spectrum Disorders (HFASD) and fourteen typical individuals were presented naturalistic and interactive social stimuli using virtual reality. Fixation data showed a weaker modulation of eye movements according to the conditions in the HFASD group, thus suggesting impairments in self-monitoring of gaze. Moreover, the gaze-contingent lens induced a visual behaviour whereby social understanding scores were correlated with the time spent gazing at faces. The device could be useful for treating gaze monitoring deficiencies in HFASD.

Gaze represents a major non-verbal communication channel in social interactions. In this respect, when facing another person, one's gaze should not be examined as a purely perceptive process but also as an action-perception online performance. However, little is known about processes involved in the real-time self-regulation of social gaze. The present study investigates the impact of a gaze-contingent viewing window on fixation patterns and the awareness of being the agent moving the window. In face-to-face scenarios played by a virtual human character, the task for the 18 adult participants was to interpret an equivocal sentence which could be disambiguated by examining the emotional expressions of the character speaking. The virtual character was embedded in naturalistic backgrounds to enhance realism. Eye-tracking data showed that the viewing window induced changes in gaze behavior, notably longer visual fixations. Notwithstanding, only half of the participants ascribed the window displacements to their eye movements. These participants also spent more time looking at the eyes and mouth regions of the virtual human character. The outcomes of the study highlight the dissociation between non-volitional gaze adaptation and the self-ascription of agency. Such dissociation provides support for a two-step account of the sense of agency composed of pre-noetic monitoring mechanisms and reflexive processes, linked by bottom-up and top-down processes. We comment upon these results, which illustrate the relevance of our method for studying online social cognition, in particular concerning autism spectrum disorders (ASD) where the poor pragmatic understanding of oral speech is considered linked to visual peculiarities that impede facial exploration.

We report an experimental study that aims at investigating the influence of spatial layout on visual search efficiency and comfort. 4 layouts were used for displaying 120 scenes comprising 30 realistic colour photos each: random, elliptic, radial and matrix-like. Scenes (30 per structure) were presented to 5 participants who had to select a previewed photo in each scene using the mouse. Eye-tracking data indicate that elliptic layouts provided better visual comfort than any of the other layouts (shortest scan paths), and proved to be more efficient than matrix layouts (shorter search times). These results are statistically significant (paired t-tests).

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We present our current research on the implementation of gaze as an efficient and usable pointing modality supplementary to speech, for interacting with augmented objects in our daily environment or large displays, especially immersive virtual reality environments, such as reality centres and caves. We are also addressing issues relating to the use of gaze as the main interaction input modality. We have designed and developed two operational user interfaces: one for providing motor-disabled users with easy gaze-based access to map applications and graphical software; the other for iteratively testing and improving the usability of gaze-contingent displays.

RESUMECette étude expérimentale tente de cerner l'influence effective de l'organisation spatiale d'affichages graphiques sur l'efficacité de la recherche visuelle et son confort. Quatre structures ont été testées, les structures Aléatoire, Elliptique, Matricielle et Radiale, pour afficher des collections de photographies couleur réalistes (30 par collection). 120 scènes (30 par structure) ont été présentées à 10 utilisateurs potentiels. Ceux-ci devaient, le plus rapidement possible, repérer dans chaque scène et sélec-tionner à la souris une photographie qui leur avait été présentée au préalable isolément. En accord avec nos hypothèses, la position de la cible, la difficulté de la tâ-che et le sujet des photographies influencent les temps de sélection et les taux d'erreur. Les données oculomé-triques enregistrées pour 5 sujets montrent en outre que, pendant la phase initiale de localisation de la cible, la structure Elliptique offre un meilleur confort visuel que les autres structures (parcours oculaire moyen plus court) et s'avère plus efficace que la structure Matricielle (temps de localisation de la cible plus court). L'ensemble de ces résultats sont statistiquement significatifs. MOTS CLES :Recherche visuelle, organisation spatiale des affichages, parcours oculaire, analyse oculométrique, ergonomie de l'interaction homme-machine. ABSTRACTThe aim of this experimental study was to investigate the possible influence of spatial layout on the efficiency and visual comfort of target detection on crowded displays. Four layouts were used for presenting sets of 30 realistic colour photos: Random, Elliptic, Radial and Matrix-like. 120 scenes (30 per structure) were displayed to 10 subjects. For each scene, subjects had to detect a pre-viewed photo, and to select it using the mouse. As expected, target selection times and failure numbers were influenced by task difficulty, target position and photo subject. Eyetracking data suggest that, during the initial survey in search of the target, Elliptic layouts provided better visual comfort than any of the other layouts (shortest scan paths), and proved to be sensibly more efficient than Matrix layouts (shorter initial survey durations). All these results are significant.

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