Lecture by Floris de Lange 'Seeing is believing - How priors shape perception'

28 September 2012 from 16:15 to 17:00 hrs
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Lecture at the mini symposium Cognitive Science Heineken Prize Winners program

Abstract of the lecture

Information from our senses enters our brain, where it is elaborated and transformed into percepts. I will argue that this influential textbook view of perception may be wrong, as it does not do justice to the enormous influence that priors (embodying our knowledge and expectations of the world around us) have in biasing and determining perception. In my talk, I will discuss a series of studies that show how different kind of expectations (associations, context, language) shape neural processes in early visual and auditory cortices, and bias our eventual perceptual decisions.

Perception is not simply a passive process of accumulation of sensory evidence, but it is strongly shaped by internal brain states, which incorporate our goals, attention, expectations, and knowledge about the world. In my talk, I will focus on how expectation shapes perception. Does it “change the evidence” or “change the weight of the evidence”?

I will discuss recent neuroimaging data (MEG and fMRI) and multivariate methods (MVPA) that show how expectation reduces neural activity in early sensory cortex, yet boosts the amount of information that can be “read out” from these areas. In conclusion, I will argue that priors in the brain both “change” and “weight” sensory evidence during perceptual decision-making.