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Top-down vs. bottom-up? Effects of prediction and attention on sensory processing and perception

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Perception is more than meets the eye: how we see the world is critically shaped by attention (what is relevant) and as a growing body of work indicates, by expectations derived from past experience (what is likely). Overturning the classical notion of perception as a largely bottom-up process of feature detection and evidence accumulation, the idea that our brain is a prediction machine, continually trying to predict what is ‘out there’ based on past experience, is quickly growing in stature and influence. Yet, little is still known about how predictions shape perceptual experience, independently and/or in interaction with attention. In my talk, I will present results from several behavioral and EEG experiments to address two specific outstanding issues. First, predictive processing theories propose that predictions reduce sensory signals as early as primary visual cortex (V1), and that attention can modulate these effects. Indeed, both prediction and attention have been shown to modulate V1 activity, albeit with fMRI, which has low temporal resolution. This leaves it unclear whether these effects reflect a modulation of the first feedforward sweep of visual information processing and/or later, feedback-related activity. In two experiments, we used EEG and orthogonally manipulated spatial predictions and attention to address this outstanding question. Although clear top-down biases were found, as reflected in pre-stimulus alpha-band activity, no evidence was found for top-down effects on the earliest visual cortical processing stage (

Bio

Heleen Slagter is Professor of Cognitive Neuroscience at the VU University of Amsterdam. She received a PhD in cognitive neuroscience in 2005 from the University of Amsterdam. After a 4-year postdoc at the University of Wisconsin-Madison, USA , she returned to Amsterdam to set up her own lab. Her research focuses on (the neural basis of) core cognitive functions, such as attention, and the plasticity of these functions. What are the mechanisms that allow us to perceive, select, suppress, and become aware of information in the environment? How does learning based on prior experience or mental training as cultivated by meditation influence these mechanisms that adaptively control information processing? Dr. Slagter’s work has garnered awards and funding, including a prestigious VIDI grant by the Netherlands Organization for Scientific research, an ERC starting grant, and an early career award by the Society for Psychophysiological Research.

This talk is part of the Zangwill Club series.

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