In this research project, we are interested in the strategies used to explore efficiently a complex visual scene composed of multiple targets and multiple distractors. In situations in which individuals search for different targets simultaneously (e. g., all the red dots and green squares in the display on the right), while avoiding distractors (e. g., red squares and green dots), some people exhaust one entire target category before switching to the second target category, while others gradually proceed in the visual space keeping the two target categories in working memory throughout the experiment. The research project aims at examining oculomotor dynamics during such tasks so as to identify how the strategies employed by observers modify their oculomotor behavior, and, reversely, how individual differences in visual exploration come with individual differences in foraging strategy.
Since 2025, this research is part of the MULTIFOR project funded by the French National Research Agency: https://anr.fr/Project-ANR-24-CE28-3988
Collaborators:
Pr. Karine Doré-Mazars (Univ. Paris Cité)
Ph.D student Maha Haggouch (Univ. Paris Cité)
Pr. Árni Kristjánsson (University of Iceland)
Dr. Laura Lazartigues (Univ. Lille)
Pr. Stéphanie Mathey (Univ. Bordeaux)
Pr. Christelle Robert (Univ. Bordeaux)
Pr. Ian M. Thornton (University of Malta)
The link between space and number processing is widely reported in the literature. In the brain, numbers are represented on a mental number line that facilitates the processing of small numbers in the left hemispace and of large numbers in the right hemispace. These "space-number associations" are observed through their influence on action parameters (reaction times, action magnitude). In this research project, we aim at demonstrating that action can, in turn, influence number representations, independently of the influence of space.
Collaborators:
Dr. Alexandra Pressigout (Suricog, Paris)
Pr. Karine Doré-Mazars (Université Paris Cité)
This project, led by Prof. R. Delorme at Hôpital Robert Debré, aims at characterizing behavioral endophenotypes of autism spectrum disorders (ASD). We asked children with ASD and their parents to perform a facial emotion recognition task while recording their eye movements. Past research has shown that children with ASD make more eye fixations on the mouth than on the eyes of the emotional face, whereas children without ASD make more eye fixations on the eyes than on the mouth of the emotional face. We here investigate whether the parents of children with ASD show similar differences in visual exploration. The influence of other individual characteristics such as IQ and alexithymia are also examined.
Collaborators:
Dr. Corentin Gosling (Paris Nanterre University)
M. Sc. Ariane Cartigny (Neuropsychologist, Hôpital Robert-Debré, AP/HP, Paris)
Dr. Alicia Cohen-Freoua (Psychatrist, Hôpital Robert-Debré, AP/HP, Paris)
Pr. Richard Delorme (Hôpital Robert Debré, AP/HP, Paris)
This project aims at examining how perceptual and motor asymmetries can influence attentional and oculomotor processes. Functional asymmetries such as the lateralization of visuo-spatial attention networks and the lateralization of local and global processing of visual information are considered. In other studies, we also examine how lateral preferences, such as handedness and sighting eye dominance, can play a role in perceptual and visuo-motor processes. To do so, we measure saccadic parameters in the left and right visual hemifields, in individuals with left or right handedness and sighting eye dominance. As shown in the graph on the right, our results for example show that saccade accuracy (measured in a global effect paradigm) is higher in the hemifield contralateral to the dominant eye than in the ipsilateral hemifield. Such results are discussed with regards to the neural architecture of the oculomotor system, and we show that eye dominance and perceptual asymmetries should be considered in future models of oculomotor control.
Collaborators:
Pr. Dorine Vergilino-Perez (Paris Descartes University)
Pr. Karine Doré-Mazars (Paris Descartes University)
Dr. Christelle Lemoine-Lardennois (Paris Descartes University)
Contrary to handedness, which is assessed on a continuous scale with questionnaires, sighting eye dominance is assessed with tests (e. g., “hole-in-card test”) providing a binary measure: left or right dominant eye. Here, we show that performance at basic oculomotor tasks (reactive and voluntary prosaccades) varies with the degree of eye dominance strength. Hence, this research projects aims at computing a continuous scale of eye dominance strength based on oculomotor performance. One of our study for example shows that classic saccadic asymmetries between nasal and temporal hemifields, or between centripetal and centrifugal saccades, are associated with weak eye dominance. Based on these results, we have computed a continuous scale of eye dominance strength, where strong saccadic asymmetries is associated with no eye dominance and no saccadic asymmetries with very strong eye dominance (see figure below; %EDS-NTA refers to percentage of eye dominance strength based on the naso-temporal asymmetry). Overall, this research project involves both group-level and individual-level analyses. The obtained results are interpreted in relation with the neurophysiological bases of saccadic asymmetries and eye dominance.
Collaborators:
Pr. Dorine Vergilino-Perez (Paris Descartes University)
Pr. Karine Doré-Mazars (Paris Descartes University)
Dr. Christelle Lemoine-Lardennois (Paris Descartes University)
M. Sc. Judith Vergne (Paris Descartes University)