The perception-cognition border: A case for architectural division The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Green, E. J. “The perception-cognition border: A case for architectural division.” Philosophical Review, 129, 3 (July 2020): 323-393 © 2020 The Author As Published 10.1215/00318108-8311221 Publisher Cornell University Press Version Author's final manuscript Citable link https://hdl.handle.net/1721.1/130159 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ The Perception-Cognition Border: A Case for Architectural Division* E. J. Green, MIT Penultimate draft (forthcoming, The Philosophical Review) Abstract: A venerable view holds that a border between perception and cognition is built into our cognitive architecture, and that this imposes limits on the way information can flow between them. While the deliverances of perception are freely available for use in reasoning and inference, there are strict constraints on information flow in the opposite direction. Despite its plausibility, this approach to the perception-cognition border has faced criticism in recent years. This paper develops an updated version of the architectural approach, which I call the dimension restriction hypothesis (DRH). According to DRH, perceptual processes are constrained to compute over a bounded range of dimensions, while cognitive processes are not. This view allows that perception is cognitively penetrable, but places strict limits on the varieties of penetration that can occur. I argue that DRH enjoys both theoretical and empirical support. I also defend the view against several objections. 1. Introduction Many philosophical debates presuppose that there is a border between perception and cognition. This assumption is salient in discussions of the epistemic role of perceptual experience, the rich/thin debate about perceptual content, and the role of perception in fixing demonstrative reference. But is the assumption correct? If so, how should the perception-cognition border be characterized? A venerable view holds that the perception-cognition border is marked by constraints on the way information flows between them. On this approach, the mind’s cognitive architecture contains a stable information-processing boundary between perceptual processes and cognitive processes. This boundary ensures that while the outputs of perceptual processing are freely available for use in cognition, there are strict constraints on information flow in the opposite direction (Fodor 1983, 2000; Pylyshyn 1999). Call this the architectural approach to the perception-cognition border.1 Recently it has been suggested that the architectural approach is out of date and in need of replacement. Clark (2013), for instance, claims that pervasive top-down effects render the border * Thanks to Alex Byrne, John Morrison, Tyler Wilson, and two reviewers for this journal for helpful comments on earlier drafts of this paper. I am also grateful to Jonathan Cohen, Steven Gross, Eric Mandelbaum, and Jake Quilty-Dunn for extended discussion of these issues. Portions of this material were presented at the 2018 Eastern APA Meeting, the University of Illinois-Chicago, and Princeton University. I thank the audiences on these occasions for their valuable feedback. 1 See also Quilty-Dunn (2018) for this terminology. 1 between perception and cognition “fuzzy, perhaps even vanishing” (190). Some have even proposed eliminating the perception/cognition distinction from our theoretical vocabulary (Clark 2013; Lupyan 2015b, 2017; Shea 2014). Others have instead opted for non-architectural theories of the perception-cognition border. Block (forthcoming) suggests that the perception-cognition border should be drawn by appeal to differences in representational format. Beck (2018) and Phillips (2017) suggest that perceptual states, unlike cognitive states, function to be stimulus-dependent. Ogilvie and Carruthers (2015) propose replacing the architectural approach with a neurofunctional characterization on which the visual system consists of “the set of brain-mechanisms specialized for the analysis of signals originating from the retina” (722). In contrast to these views, this paper develops and defends an updated version of the architectural approach. I’ll argue that we can take seriously the abundance of evidence in favor of top-down effects on perception while also preserving the insight that there is a deep architectural boundary between perceptual and cognitive processes. The most familiar version of the architectural approach holds that perception is cognitively impenetrable (Pylyshyn 1999). Roughly, perceptual processing is immune from influences of the agent’s beliefs, desires, or intentions.2 A number of challenges to this view (and, in my opinion, the most empirically secure among them) have relied on pre-cueing effects, in which instructions to expect or covertly attend to an upcoming stimulus alter perceptual processing of that stimulus in a way that makes sense given the instructions.3 Thus, cues to expect or attend to specific colors (Störmer & Alvarez 2014), orientations (Kok et al. 2012), motion directions (Serences & Boynton 2007), and 2 The cognitive impenetrability thesis is obviously related to the view that perceptual systems are modular while cognitive systems are not (Fodor 1983). However, because modularity incorporates further characteristics beyond architectural constraints on information flow (e.g., domain-specificity, innateness, and dedicated neural substrate), I’ll restrict my attention to the impenetrability thesis. 3 For challenges of this sort, see Block (2016), Clark (2016), Lupyan (2015a, 2017), Masrour et al. (2015), Ogilvie and Carruthers (2015), Teufel and Nanay (2017), and Vetter and Newen (2014). 2 shapes (Stokes et al. 2009) result in systematic changes to the responses of visual brain areas that process information about these dimensions. There is a lively debate about whether such effects constitute cognitive penetration. (The issue is subtle, and I’ll consider it in detail in section 5.) Suppose for now, however, that they do. Is the architectural approach to the perception-cognition border thereby defunct? In what follows, I’ll argue that we can preserve the architectural approach while permitting constrained forms of cognitive penetration. On the account I’ll offer, perceptual processes are marked by dimension restriction, while cognitive processes are not. Individual perceptual processes are constrained to compute over a bounded range of dimensions, and this range cannot be modified through cognitive influence. For example, a perceptual process might be constrained to compute only over the dimensions of brightness, orientation, and motion. If so, then the agent cannot change this fact, no matter her desires or beliefs. My aims, then, are threefold: (i) to articulate the dimension restriction hypothesis in more detail, (ii) to defend the hypothesis against several pressing challenges, and (iii) to argue that the view has advantages over its main rivals. The structure of the paper is as follows. Section 2 presents the dimension restriction hypothesis (henceforth DRH) and argues that the view preserves a key idea motivating earlier versions of the architectural approach—namely, that cognition is isotropic, while perception is not. Section 3 considers and replies to several challenges to DRH. Section 4 argues that DRH enjoys empirical advantages over competing views that seek to eliminate information-flow constraints at the perception-cognition border. Section 5 contrasts DRH with cognitive impenetrability, and argues that while pre-cueing effects are compatible with dimension restriction, they raise problems for impenetrability that cannot be finessed through standard maneuvers. Section 6 concludes. Three qualifications before we get started. First, I am concerned to characterize the border between perception and cognition. I won’t be offering necessary and sufficient conditions for being 3 perceptual (or cognitive). As Beck (2018, 322) observes, these are different projects. An adequate theory of the perception-cognition border needs to provide criteria for determining whether a state is perceptual or cognitive provided that we are antecedently confident that it is one or the other. I suggest that dimension restriction plausibly plays this role, but I don’t claim that it is sufficient for being perceptual, since there may be systems that are neither perceptual nor cognitive that also exhibit dimension restriction (e.g., specialized motor or affective systems). Second, my defense of DRH will center on examples drawn from vision. Nonetheless, it is my hope that the view will generalize to the other senses. Moreover, if the view is right, then it should also characterize multisensory processes like those responsible for the ventriloquism effect and other cross-modal illusions. I don’t doubt that these cases present unique theoretical challenges, but their exploration must be left for another time. Third, I allow that there may be some borderline cases of processes that are neither determinately perceptual nor determinately cognitive. But surely almost every psychological category has borderline cases, so why should perception and cognition be any different? The real challenge is to significantly limit the range of borderline cases so that the perception-cognition distinction remains theoretically