Thesis defense Jordy Thielen (Donders series 521)

21 January 2022

Promotors: prof. dr. R.J. van Lier, prof. dr. M.A.J. van Gerven
Co-promotors: dr. S.E. Bosch, dr. T.M. van Leeuwen

What determines vision? Bottom-up and top-down influences on visual perception

What we visually perceive is a combination of the sensory information that reaches our eyes (bottom-up) and what the brain itself fills in based on expectations and internal goals (top-down). Jordy Thielen investigated how the brain completes information when the sensory information is incomplete. His research shows that multiple neural processes and several different brain areas are involved in perceptual completion and that there is no unequivocal underlying mechanism. Additionally, he showed that participants make, during specific attention-tasks, small systematic eye movements, even when they were explicitly asked not to make eye movements. This finding is a serious warning about the interpretation of among other things brain data. Finally, he developed a new advanced method, using artificial intelligence, to measure complex characteristics of the primary visual cortex. Also this last study shows that the visual world in which we live is the result of a complex interplay of processes in the visual brain.