The cognitive penetration of perception is typically defined as a phe-nomenon that influences the content of perceptual experience (Macpherson 2012; Siegel 2012, 2013c; Siegel and Silins ming; Stokes 2012, 2013; Stokes and Bergeron ming). Our cognitive states can influence what we see, hear, touch, and the like. For instance, knowledge about objects’ colour can influ-ence perceptual content modifying the hue of the experiential object (Delk and Fillenbaum 1965; Olkkonen et al. 2008; Witzel et al. 2011). Believing that someone is angry at us might influence our visual experience, making us see the person as having an angry facial expression (Siegel 2012). Knowl-edge of racial features could influence how we perceive the colour of faces (Levin and Banaji 2006). Acrophobia (fear of heights) may influence the perception of vertical distances, making subjects overestimate it. And so on.
The cognitive penetration of perception is frequently discussed with re-gard to vision, and this thesis will not be an exception to this rule. Visual perception is normally considered as a process composed of two stages: early and late vision. Early vision is the first stage of visual processing. It is de-fined as a modular system whose main property is to be informationally encapsulated from other systems (e.g., the cognitive system). At this level, the visual system produces primitive outputs that are further processed by late vision. The late visual stage is not modular. Because visual objects need to be categorized, the process requires the interaction of visual
in-coming information and memory. (See, e.g., Pylyshyn(1984, 1999a, 2003);
Raftopoulos (2001c, a, b, 2009a).) The resulting output is the perceptual experience.
The cognitive penetrability of perception can be understood as the cog-nitive penetrability of perceptual experience (Macpherson 2012;Siegel 2012, 2013c;Stokes 2012,2013) or early vision (Fodor 1983,2000;Pylyshyn 1984, 1999a, 2003; Raftopoulos 2001c, a, b, 2009a). These two phenomena are different from each other, though. A perceptual experience can be pene-trated, while the underlying process in early vision is not. And an early visual process can be penetrated without having any impact on experience.
In this framework, perceptual experience is the result of the whole visual process (the conjunction of early and late vision). So cognitive penetration could occur in late vision (a non-encapsulated system) or early vision. Quite importantly, a perceptual experience corrupted at the late visual level can be as pernicious as an experience influenced in early vision.
However, those authors who define cognitive penetration as a problem concerning early vision claim that the cognitive penetration of perceptual experience at the late visual level does not represent an issue. Cognitive influences in late vision only affect how the object is categorized but do not influence visual processing. In addition, they claim that the early vi-sual system is a cognitively encapsulated module: the subject’s cognitive background does not influence the processing inside the module. Then, cognitive encapsulation preserves the objectivity and reliability of the vi-sual process (Pylyshyn 1980; Fodor 1983, 43, 68; Pylyshyn 1984, 155).
Raftopoulos (2001c, 188) claims that perception is bottom-up and theory neutral, in a way that “it can play the role of common ground on which a naturalized epistemology could be built and relativism could be avoided”.
Therefore, cognitive impenetrability of early vision preserves perceptual jus-tification. The cognitive encapsulation of early vision in Fodor, Pylyshyn and Raftopoulos has as the aim to make “the world safe for justified belief”
(Lyons 2011, 305).
The aim of this thesis is to show that early vision is cognitively
penetra-ble. In fact, in chapters 3 and 4, I scrutinize the phenomenon of cognitive penetration and, in chapters 5 and 6, I provide empirical evidence show-ing that early visionis cognitively penetrable form the beginning of visual processing. That is, the early visual system is not informationally encap-sulated from cognition: in order to process its inputs, it needs cognitive intervention. Therefore, perceptual justification is not safe from cognitive penetration. In other words, the aim of this thesis is to show that cognitive penetration is an ubiquitous phenomenon that influences all the stages of visual processing. The motivation to examine early vision is the claim — made by some psychologists and philosophers — that the cognitive impen-etrability of early vision preserves perceptual justification.
In this thesis, I will characterize the visual system as a visuo-motor system composed of motor functions, early and late vision (Fodor 1983;Wu 2013). Motor functions designates those peripheral mechanisms responsible for the guidance of eye movements and the attentional focus. Early and late vision refer to the central part of the system responsible for the processing of visual stimuli into perceptual experiences. I will claim that cognitive penetration is a phenomenon susceptible of affecting the three components of the visuo-motor system: motor functions, early and late vision.
Cognitive penetration can be roughly defined as those cognitive influ-ences on perceptual systems which have consequinflu-ences for the epistemic sta-tus of the subject. One of the main contributions will be the distinction of two types of cognitive penetration: architectural and content. Architec-tural cognitive penetration denotes the cognitive influences which affect the way the visual system behaves (e.g., directs attention) or processes (e.g., retrieves, transforms, stores, controls, etc.) perceptual content. This type of modulation can affect the peripheral (motor) and central (early and late visual) structures of the visual system. Content cognitive penetration des-ignates the cognitive effects on perceptual content which add, modify, or substitute any piece of information to this content. The penetrating state directly influences perceptual content. I will argue in chapter 4 that the architectural/content dichotomy can be spelled out in terms of the
chan-nel/signal distinction that underlies Dretske’s (1981) highly influential the-ory of information. The channel of the system refers to the system’s central (early and late visual) and peripheral (motor) structures. The signal de-notes the information the system processes inside the channel, to wit, its content. Modulations in thesignal of the perceptual process refer to changes in the content of perceptual states, and changes in the channel represent influences in the architecture of the system.
Finally, I will claim that architectural and content cognitive penetration might occur synchronically or diachronically. Synchronic cognitive penetra-tion occurs when the cognitive influences affect the perceptual system si-multaneously to the perceptual act. Diachronic cognitive penetration takes place when the influence of the subject’s cognitive background on the per-ceptual system is prior to perception. Therefore, two types and two sub-types of cognitive penetration can be identified: synchronic and diachronic architectural cognitive penetration, and synchronic and diachronic content cognitive penetration. I will submit that these forms of cognitive penetra-tion can occur either at early or late stages of visual processing. The main contribution of this thesis is the claim, made in chapters 5 and 6, that architectural and content cognitive penetration occur in early vision.
I have said that cognitive penetration is defined with regard to epis-temic consequences. Those cognitive influences that do not influence the visual system in any epistemically significant way do not count as cogni-tive penetration of perception. Another important aspect related to the consequences of cognitive penetration on epistemology is the nature of the penetration: whether it is beneficial or pernicious for perceptual justifica-tion. Roughly, good cases of cognitive penetration seem to be those that increase the subject’s epistemic status. The subject acquires more percep-tual justification or the reliability of the process increases. Bad cases of cognitive penetration seem to be those that produce the opposite effect:
they downgrade, undermine, or rebut perceptual justification. The problem of cognitive penetration lies then on which forms of cognitive influences on a perceptual system are benign and which are malign (Lyons 2011, 290;
Siegel 2012, 220-221; Siegel 2013c, 701-704). For instance, in some cases, believing that someone is angry at us may be beneficial to detect her angry face if the person is effectively angry. But it could be also pernicious if the person is not angry at us and our background belief makes us end up with the perceptual experience of an angry face. In chapter7, I will explain that the nature of the cognitive state (whether it is good or bad) should be determined by appeal to three features: reliability, the functioning of the visual system, and the perceptual environment.
To summarize, three aspects of cognitive penetration will be scrutinized in this thesis: how many types of cognitive penetration there are, what is the locus of the penetration, and when cognitive influences are beneficial or pernicious. I will argue first that cognitive penetration can influence either the architecture or the content of the system and can be synchronic and diachronic. Second, the locus of this penetration can be motor mechanisms, early vision, and late vision. And finally, benign and malign cases of cog-nitive penetration depend on the reliability of the system as well as on its functioning, and the perceptual environment.
In the last chapter of this thesis, I will briefly discuss the consequences of cognitive penetration for Fodor’s modularity theory. I will also analyse the consequences of cognitive penetration for theories of perceptual justification.
I will suggest that, although cognitive penetration poses a problem for most theories of perceptual justification, only some externalist theories are able to deal with this phenomenon. Let’s examine now perceptual justification and the different theories that will be considered in this thesis.