Cognitive penetration and top-down modulation in visual perception

Dimitria Electra Gatzia (University of Akron, University of Antwerp)

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Abstract: Cognition can influence action. Your belief that it is raining outside, for example, may cause you to reach for the umbrella. Perception can also influence cognition. Seeing that no raindrops are falling, for example, may cause you to think that you don’t need to reach for an umbrella. The question that has fascinated philosophers and cognitive scientists for the past few decades, however, is whether cognition can influence perception. Can, for example, your desire for a rainy day cause you to see, hear, or feel raindrops when you walk outside? More generally, can our cognitive states (such as beliefs, desires or intentions) influence the way we see the external world? In the first part of this paper, I present evidence of top-down modulation in early vision. In the second part of the paper, I make a distinction between two types of top-down modulation. The first pertains to the unconscious visual ‘inferences’ the visual system makes as it ‘chooses’ among many possible representations to arrive at one that we experience as a conscious precept (or back-end effects). The second pertains to the cognitive states of perceivers, which may be used to alter the function the visual system computes (or front-end effects). I use this distinction to argue that evidence for top-down modulation in early vision need not threaten the Cognitive Penetrability Thesis (CIT). Colour vision is used as a case study to show how empirical findings suggesting that colour experience is cognitively penetrated can be better explained without reference to cognitive penetration.

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