How to (and how not to) think about top-down influences on visual perception

- Whether cognition influences perception is an ongoing debate with a long history.
- This issue should be viewed within the general framework of top-down information processing.
- Such an approach leads to a reversal of the standard explanatory order.
- Top-down processing within the visual system can serve as a model for higher-level influences.
- From this perspective, the current evidence does not favour the cognitive impenetrability hypothesis.

The question of whether cognition can influence perception has a long history in neuroscience and philosophy. Here, we outline a novel approach to this issue, arguing that it should be viewed within the framework of top-down information-processing. This approach leads to a reversal of the standard explanatory order of the cognitive penetration debate: we suggest studying top-down processing at various levels without preconceptions of perception or cognition. Once a clear picture has emerged about which processes have influences on those at lower levels, we can re-address the extent to which they should be considered perceptual or cognitive. Using top-down processing within the visual system as a model for higher-level influences, we argue that the current evidence indicates clear constraints on top-down influences at all stages of information processing; it does, however, not support the notion of a boundary between specific types of information-processing as proposed by the cognitive impenetrability hypothesis.