At the end of the 19th century, Louis-Emile Javal discovered that our eyes make jerky, saccadic movements along the lines of text during reading. Since then, the study of saccadic behavior has grown exponentially and significant advances have been made in our understanding of the relationship between the successive shifts of our eyes over a text or a scene and ongoing visual and cognitive processes. Yet, whether and how the neurophysiology of the underlying oculomotor system, also studied for decades, does constrain eye guidance in real-world tasks has largely remained unexplored. Furthermore, despite converging evidence for the universality of several eye-movement patterns across tasks and stimuli, moving the eyes to a single point, reading a novel, viewing a landscape or searching for a face in the crowd are still considered as being fundamentally different from an oculomotor point of view. In my talk, I will present an alternative, integrated view of eye-movement control, that links well-known neural properties of the oculomotor system to eye guidance in a range of tasks and stimuli. Central to this view is the rather coarse and distorted representation of visual space in the superior colliculus (SC) where saccades are being programmed, and the related hypothesis that saccades are preceded by the activity of a population of SC neurons which is invariant to translation. I will show, based on a novel neuro-computational imaging approach of saccadic behavior, that the averaging of population activity in the distorted map of the SC strongly constrains the distribution of saccadic endpoints in simple saccade-targeting tasks, while providing the first behavioral evidence for population invariance in humans. I will then present several recent findings suggesting that the same mechanisms and constraints may also shape eye guidance during reading and scene viewing, and potentially account for universal eye-movement patterns (e.g. the Preferred Viewing Position effect). I will finally discuss how this population-averaging view can be reconciled with the more popular, cognitive account of eye-movement control.
Françoise Vitu studied Psychology at the University René Descartes in Paris, France, where she received her PhD in 1990, after working with J. Kevin O'Regan. She then went to the US for a post-doc with George W. McConkie at the University of Illinois at Urbana-Champaign and Albrecht Inhoff at the State University of New York at Binghamton. During the fall 1992, after another post-doc with Gery d'Ydewalle at the Catholic University of Leuven in Belgium, she was appointed as permanent researcher at the CNRS in Paris. In 1997, she was a NATO visiting researcher at the Beckman Institute (UIUC), and during the fall 2005, she was appointed as guest professor at the University of Potsdam, Germany. In 2004, she moved to Marseille, where she now is Director of Research (CNRS), and she heads with Eric Castet, the Perception and Attention group of the Laboratory of Cognitive Psychology at Aix-Marseille University.
Françoise Vitu's early work focused on eye-movement control during reading, and aimed at determining the respective contributions of visuo-motor, linguistic, and attentional processes. It allowed her to estimate the spatial and temporal constraints associated with language-related influences, but also to isolate and characterize several oculomotor patterns that appear to be relatively universal. Being convinced that eye movements during reading and other perceptual tasks are primarily controlled by fundamental, visuo-motor principles, she recently extended her approach to object and natural-scene viewing, while also developing a new line of research that aims at linking the properties of saccades to the underlying neurophysiology of oculomotor and visual systems.