Modularist explanations of experience and other illusions

Debates about modularity invariably involve a crucial premise about how visual illusions are experienced. This paper argues that these debates are wrongheaded, and that experience of illusions is orthogonal to the core issue of the modularity hypothesis: informational encapsulation.

Perception is not all-purpose

I aim to show that perception depends counterfactually on the action we want to perform. Perception is not all-purpose: what we want to do does influence what we see. After clarifying how this claim is different from the one at stake in the cognitive penetrability debate and what counterfactual dependence means in my claim, I will give a two-step argument: (a) one's perceptual attention depends counterfactually on one's intention to perform an action (everything else being equal) and (b) one's perceptual processing depends counterfactually on one's perceptual attention (everything else being equal). If we put these claims together, what we get is that one's perceptual processing depends counterfactually on one's intention to perform an action (everything else being equal).

Cognitive penetration of early vision in face perception

Cognitive and affective penetration of perception refers to the influence that higher mental states such as beliefs and emotions have on perceptual systems. Psychological and neuroscientific studies appear to show that these states modulate the visual system at the visuomotor, attentional, and late levels of processing. However, empirical evidence showing that similar consequences occur in early stages of visual processing seems to be scarce. In this paper, I argue that psychological evidence does not seem to be either sufficient or necessary to argue in favour of or against the cognitive penetration of perception in either late or early vision. In order to do that we need to have recourse to brain imaging techniques. Thus, I introduce a neuroscientific study and argue that it seems to provide well-grounded evidence for the cognitive penetration of early vision in face perception. I also examine and reject alternative explanations to my conclusion.

When is cognitive penetration a plausible explanation?

Albert Newen and Petra Vetter argue that neurophysiological considerations and psychophysical studies provide striking evidence for cognitive penetration. This commentary focuses mainly on the neurophysiological considerations, which have thus far remained largely absent in the philosophical debate concerning cognitive penetration, and on the cognitive penetration of perceptual experiences, which is the form of cognitive penetration philosophers have debated about the most. It is argued that Newen and Vetter's evidence for cognitive penetration is unpersuasive because they do not sufficiently scrutinize the details of the empirical studies they make use of-the details of the empirical studies are crucial also when the studies are used in philosophical debates. The previous does not mean that cognitive penetration could not occur. Quite the contrary, details of the feedback connections to the visual perceptual module and one of the candidates presented by Newen and Vetter suggest that cognitive penetration can occur in rare cases.

Expectation creates something out of nothing: The role of attention in iconic memory reconsidered

Conscious experience is modulated by attention and expectation, yet is believed to be independent of attention. The experiments on iconic memory (IM) are usually taken as support for this claim. However, a recent experiment demonstrated that when attention is diverted away from the IM letter display subjects fail to see the absence of IM letters. Here we contribute to the ongoing debate by overcoming experimental shortcomings of this previous experiment, by measuring subjective visibility and by testing the effect of the post-cue. We were able to replicate these earlier findings and extend them by demonstrating that subjects who do not realize the absence of letters perceive illusory letters. This result means that there is still phenomenal consciousness, even when attention is diverted. Expectation creates illusory content that overwrites valid IM content. Taken together these findings suggest that the present experimental paradigm is not appropriate to make claims about IM content.

Predictions penetrate perception: Converging insights from brain, behaviour and disorder

It is argued that during ongoing visual perception, the brain is generating top-down predictions to facilitate, guide and constrain the processing of incoming sensory input. Here we demonstrate that these predictions are drawn from a diverse range of cognitive processes, in order to generate the richest and most informative prediction signals. This is consistent with a central role for cognitive penetrability in visual perception. We review behavioural and mechanistic evidence that indicate a wide spectrum of domains-including object recognition, contextual associations, cognitive biases and affective state-that can directly influence visual perception. We combine these insights from the healthy brain with novel observations from neuropsychiatric disorders involving visual hallucinations, which highlight the consequences of imbalance between top-down signals and incoming sensory information. Together, these lines of evidence converge to indicate that predictive penetration, be it cognitive, social or emotional, should be considered a fundamental framework that supports visual perception.

Cortical Color and the Cognitive Sciences

Back when researchers thought about the various forms that color vision could take, the focus was primarily on the retinal mechanisms. Since that time, research on human color vision has shifted from an interest in retinal mechanisms to cortical color processing. This has allowed color research to provide insight into questions that are not limited to early vision but extend to cognition. Direct cortical connections from higher-level areas to lower-level areas have been found throughout the brain. One of the classic questions in cognitive science is whether perception is influenced, and if so to what extent, by cognition and whether a clear distinction can be drawn between perception and cognition. Since perception is seen as providing justification for our beliefs about properties in the external world, these questions also have metaphysical and epistemological significance. The aim of this paper is to highlight some of the areas where research on color perception can shed new light on questions in the cognitive sciences. A further aim of the paper is to raise some questions about color research that are in dire need of further reflection and investigation.

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

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.

The relationship between cognitive penetration and predictive coding

If beliefs and desires affect perception-at least in certain specified ways-then cognitive penetration occurs. Whether it occurs is a matter of controversy. Recently, some proponents of the predictive coding account of perception have claimed that the account entails that cognitive penetrations occurs. I argue that the relationship between the predictive coding account and cognitive penetration is dependent on both the specific form of the predictive coding account and the specific form of cognitive penetration. In so doing, I spell out different forms of each and the relationship that holds between them. Thus, mere acceptance of the predictive coding approach to perception does not determine whether one should think that cognitive penetration exists. Moreover, given that there are such different conceptions of both predictive coding and cognitive penetration, researchers should cease talking of either without making clear which form they refer to, if they aspire to make true generalisations.