The broad, probably overly ambitious, agenda of the book is to shift scientific and philosophical theories of perception away from one current orthodoxy. The orthodoxy I have in mind is modularity. The alternative I favor is malleability.
That, in any case, is my attempt to distill some of the main themes of the book. I want to thank my excellent commentators in advance—Becko Copenhaver, Jonna Vance, and John Zeimbekis. I look forward to their feedback and learning from their criticism. Thank you also to Dan Burnston for pitching the idea for this symposium and to he and others at the Brains Blog for seeing it through.
If one is compelled by these claims and their support, then in some sense the epistemology follows easily. Within a domain, perceptual experts perform reliably, rapidly, and with less distraction. They approach optimality. It is worth marking this as another (I hope) important shift in the book: an emphasis on cases of expertise is an emphasis on good-making cases of cognitive influence on perception (by contrast to the cases of error that populate the cognitive penetration literature). And so in Chapter 7 I argue that this successful performance, qua performance of the agent, is best understood in virtue-theoretic terms. This requires that perception can genuinely improve, and not merely as a matter of normal development or exposure to stimuli. Some experts acquire, through concept and category-rich cognitive training, through deliberate activity, a skill. The expert radiologist performs better visually because of what she has done, because of her actions, as a responsible epistemic agent. As a consequence of this training, her perceptual systems perform in exceptional ways within that domain. And those levels of performance near maximally satisfy the natural norms for perception, thus fulfilling the representational function of perception in optimal or near-optimal ways (in that domain). The important epistemic difference between this case and the cases of mere development or exposure is that the agent is herself responsible for the relevant etiology and, accordingly, for the perceptual improvement. The epistemic virtue is therefore attributable to the agent herself (not just, say, her visual system). In cases of expertise, thinking thus improves perceiving.
The second approach, and the one that I pivot to around the middle of the book, is to stop talking about modularity and cognitive penetration. There, I said it. More carefully, I suggest that modularity does not deserve the status of default theory for the architecture of perception. This default position assumption is made by theorists on both sides of the debate, as evidenced by the pattern that pervades the cognitive penetrability literature. Opponents to modularity argue that a case violates some feature of modularity; proponents then deny that violation and maintain that modularity survives. Repeat. For this assumption to hold, for modularity to be the theory against which an alternative theory must position itself, that theory must be supported either by strong arguments or by superior explanatory power. Modularity enjoys neither. I defend this evaluation by, first, criticizing the clearest and most formidable arguments for informationally encapsulated perception. Those arguments center around the stability and reliability of perception, and none are strong enough to support the assumption in question. The rest of the book then makes the case that a malleable architecture better explains a large range of recent empirical studies and data.
As many readers will also know, challenges to modularity take the form of empirically grounded counterexample. A theorist identifies a case or set of studies where it appears that cognition is affecting perception and argues that the case is best explained as an instance of cognitive penetration, rather than a mere intra-perceptual effect, an effect on pre-perceptual attention, or an effect on post-perceptual cognitive states such as judgment or belief. There have been some promising putative counterexamples in recent years but suffice it to say that the debate has not really budged much.
Those studies concern perceptual expertise. A working characterization of ‘perceptual expertise’ underscores the following features: perceptual experts skillfully perform in a specific domain of training, their performance success is above a threshold set by the standards of that domain, and their performance non-trivially involves sensory perception. Such experts have been studied across a wide range of domain, from radiology to ornithology to fingerprint examination to elite athletics. Researchers use a range of behavioral, physiological (e.g. eye-tracking), and neurological measures (e.g. fMRI and EEG recordings). They also train subjects to become experts regarding “real-world” objects (e.g. cars or birds) and lab-created objects (e.g. “Greebles”), to better understand the acquisition and development of expertise. The best explanation of many of these phenomena is that the expertise is partly resident in the perceptual experiences of the expert, and those perceptual differences (by contrast to novices or the naïve) depend upon the richly cognitive training of the expert.
 I know I know…nerdy acronyms.
Dustin Stokes-University of Utah
It is in this way that I support the claim that thinking affects perceiving (the TaP thesis), and in many cases thinking improves perceiving (the TiP thesis). The TaP thesis divides into two architectural claims: 1) Some cases of perceptual expertise are genuinely perceptual, insofar as they involve differences in perceptual experience, and 2) those perceptual differences are sensitive to the cognitive learning specific to the domain of expertise. Of the first claim, studies on expertise show robust similarities with facial recognition (an undeniably perceptual phenomenon), where experts display standard behavioural and neural markers. Experts enjoy rapid and often “automatic”, successful performance and display significant differences in eye movement patterns. And they enjoy advantages in visual short term memory. This convergence of data (which I can only gesture at here) is best explained perceptually. By the same token, those perceptual differences depend upon the cognitive etiology of the expert, and this is the second architectural claim. Experts’ performance success, and persistence of that success, varies with fine grained learning of categories, and those changes are corroborated by lasting neural changes. Accordingly, mere “practice” or exposure to relevant stimuli is often insufficient for expert performance. And these skills tend not to “transfer” to similarly complex tasks in domains outside of the expert’s field. Perceptual experts are perceptual experts.
The TaP and TiP theses are the descriptive and normative components of a theory of how thought may affect perception, of how the mind is richly malleable. Important consequences follow. But since I haven’t the space to expound at length about them, I’ll offer (more?) provocation in hopes to compel a few readers. Accuracy is but one facet of perceptual success and thus just one possible determinant of perceptual content. Perceptual success can also involve increased sensitivity to gestalts, patterns, and feature types, achieved rapidly and efficiently, integrated with action, and with less distraction. Success along these measures can vary from domain to domain and so it follows that perceptual content is not determined in a purely mind-independent Objective* way, but instead in an inter-subjective, objective way. Determinants of content thus include facts about the environment, but also facts about the perceiver’s epistemic community. This is to accept theory-ladenness, both in science and in the ordinary course, and with that comes important risks and possible vices. One such vice that is discussed is implicit bias and the “cross-race effect” in facial recognition. It is also to accept rich perceptual content but without admission of kinds into that content. Enhanced perceptual sensitivity as enjoyed by experts– to patterns, gestalts, and organizational features – is to enjoy rich perceptual content. Importantly, this lesson is partly learned by considering cases of perceiving aesthetic properties: The ballet instructor sees not only the colours, edges, shapes, and motion of her pupils but also how those features are organized in ways that are balanced or serene or graceful. Some aesthetic experts are perceptual experts. Finally (for now), the phenomenon is general. Although the experts described here are remarkably accomplished, they are not super-humans. All humans are habit forming and many of those habits involve perception in non-trivial ways. Therefore, genuine perceptual expertise is, I suggest, a pervasive phenomenon. We are all of us potentially perceptual experts and in a variety of contexts. To accept this kind of malleability is, I think, to better understand ourselves and our place in the world.
Anyone familiar with relevant literature knows that the controversy here concerns the modularity of perception, of the strong Fodorian variety. Few if any theorists debate that cognitive states like belief or desire or intention can influence one another, that one’s values can influence how one reasons, that a decision can and should be informed by one’s motivations, and so on. It should be only slightly more controversial that sensory processes and states influence one another, vision can affect audition and vice versa, and likewise for other senses. The continued debate concerns whether those cognitive states can influence, in some important way, perceptual experience. The strong modularist maintains that this influence does not, or rarely, occur. Perceptual processing is informationally encapsulated and therefore cognitively impenetrable.
 A distinct reason to abandon talk of the latter is that it is, let’s be clear, an ugly phrase.
The book takes two broad approaches to budge things. The first is the more familiar approach, and is the approach that I have taken in the past; provide empirically grounded counterexamples to the alleged informational encapsulation of perception. In this case, I at least attempt to shed some new light in a couple of ways. I suggest that extant attempts to define cognitive penetrability as such have largely failed and result in unhelpful theoretical cross-talk. I suggest that in place of a “real definition”, we characterize the phenomenon in terms of its consequences. The proposal I conclude with is disjunctive consequentialism, which says that “ψ is cognitive penetration if and only if ψ is a cognitive-perceptual relation, and ψ implies consequences for theory-ladenness or the epistemic role of perception or the behavioural role of perception or mental architecture” (106). I also argue that the modularists’ standard take on attention-mediated instances of cognitive influence on perception is misguided. There are plausible cases where cognition influences covert selective attentional mechanisms—such as feature based and object based attention; FBA and OBA—and whereby this in turn influences conscious perceptual experience. There are two ways to argue that such cases are instances of cognitive penetration. First, these mechanisms are part of perception rather than a gatekeeper between cognition and perception. Therefore, a cognitive influence on FBA/OBA is a direct cognitive influence on perception. This is framed in terms of biased competition models of perception. Second, one can argue that such influences amount to cognitive penetration by virtue of bearing important consequences for our epistemological and/or architectural theories of perception.