ANR VISION 3E

Perceiving is essentially a decision process, whereby our brain has to deal with multiple uncertain and often ambiguous elements from the sensory input to make sense of the world. This is particularly evident with multistable, ambiguous visual stimuli, where multiple interpretations (percepts) are possible for a single physical stimulus. In this condition, human observers spontaneously alternate between the possible percepts at unpredictable times. This phenomenon has intrigued brain scientists and philosophers for decades, who have addressed questions like “What pushes our brain to switch to a new percept?”, “What factors, in the observer’s experience, conscious will, or learnt behaviors, can help or interfere with perceptual multistability?”.
Another important property of human visual processing is that it is strongly non uniform, meaning that only the central part of the image projected to the eye, reaching the fovea, is processed with high resolution. Therefore, a reliable analysis of the sensory input requires a sequential sampling of information (e.g. collecting different viewpoints and local detailed observations), which is achieved with incessant eye movements: we call this active vision.
Vision-3E builds on the assumption that visual perception results from a dynamic functional loop, which consists of three major building blocks : Expectation about the physical world (through our internal beliefs), Exploration of the sensory evidence, and Exploitation (monitoring) of the combined information resulting from expectation and exploration, to build or update a stable percept of the world. Rather than a mere feed-forward construct we assume fully recurrent connections, since for instance percept-related activity projects back onto the early sensory processing levels, leading in turn to a more focused filtering of the sensory evidence.
We aim at collecting behavioural and physiological evidence about these three key functions— expectation, exploration, and exploitation, in order to better understand and model their interaction. Importantly we also make the assumption that eye movements participate actively to the functional closed-loop, contributing to the sensory exploration and to the filtering of information leading to stabilise the percept (in the exploitation phase).
Hence we will use multiple techniques (visual psychophysics, eye tracking, EEG, fMRI-guided neuro-stimulation) with innovative experimental designs, as well as computational modelling, to achieve a comprehensive understanding of active visual decision-making. We will focus on the particular framework of multistable perception, but we will exploit the consortium synergy to be able to generalize results and interpretations across different visual ambiguous stimuli and different experimental manipulations. The originality of Vision-3E is three-fold: First, as already mentioned, the role of eye movements for perceptual decisions will be thoroughly addressed (including with specific interventional experiments selectively perturbing them). Second, we will integrate a dynamic model of the sequential decisions leading to percept reversals in the standard theoretical stationary framework of multistability. Third, we will extract (offline, then online) oculomotor and EEG markers that will be directly fed into the model, and eventually test its predictive power (offline and online) about forthcoming percept reversals. The online closed-loop stimulation, involving fast computation on the EEG-model-TMS chain is the most ambitious and slightly risky development of the project.
Feasibility and success of the workplan are granted by the strong collaborative attitude and complementary expertise of the consortium members, across five labs and three sites, all provided with state of the art equipment.

See the publications in the HAL-ANR Portal