Thesis
Reference
Modularity, cognitive penetration and perceptual justification
CECCHI, Ariel Sebastianos
Abstract
This thesis defends the cognitive penetration of perception. Cognitive penetration can be roughly defined as those cognitive influences on perceptual systems which have consequences for the modularity of mind and epistemic theories of perceptual justification.
The thesis focuses mainly on the visual system and shows that cognitive penetration occurs in early and late vision. The results of this thesis are supported by philosophical arguments as well as empirical evidence.
CECCHI, Ariel Sebastianos. Modularity, cognitive penetration and perceptual justification. Thèse de doctorat : Univ. Genève, 2014, no. L. 822
URN : urn:nbn:ch:unige-449966
DOI : 10.13097/archive-ouverte/unige:44996
Available at:
http://archive-ouverte.unige.ch/unige:44996
Disclaimer: layout of this document may differ from the published version.
Penetration
and Perceptual Justification
Ariel S. Cecchi
———
Th`ese de doctorat `es lettres Universit´e de Gen`eve
Directeur de th`ese
Professeur Pascal Engel, Universit´e de Gen`eve Pr´esident du Jury
Professeur Marcel Weber, Universit´e de Gen`eve
2014
for their love, patience, support and friendship.
With all my love
Acknowledgments ix
Abstract xiii
1 Introduction 1
1.1 Cognitive Penetration. . . 4
1.2 Cognitive Penetration and Perceptual Justification. . . 8
1.3 Structure of the Thesis . . . 17
2 The Visual System 21 2.1 Visual and Cognitive Systems . . . 24
2.1.1 Early Vision . . . 26
2.1.2 Late Vision . . . 34
2.1.3 The Cognitive System . . . 40
2.2 Modularity . . . 46
2.2.1 Informational Encapsulation of the Visuo-Motor System 51 2.3 Visual Properties . . . 58
2.3.1 Properties Represented in Early Vision . . . 62
2.4 Hypothesis Adopted . . . 66
3 Cognitive Penetration of Vision 75 3.1 Cognitive Penetration of Perception . . . 77
3.2 Three Types of Cognitive Penetration of Perception . . . 83
3.2.1 Cognitive Penetration of Perceptual Experience . . . 85
3.2.2 Cognitive Penetration of Perceptual Content . . . 87
3.2.3 Cognitive Penetration of Non-Content-Related Per-
ceptual Mechanisms . . . 94
3.3 Cognitive Penetration of Perception and Epistemic Implications104 3.4 The Content of Perception . . . 111
3.4.1 Cognitive Penetration and Nonconceptual Content of Perception . . . 112
3.5 Strong and Weak Cognitive Penetration of Perception . . . . 121
4 Characterisation of Cognitive Penetration 125 4.1 Penetrating Aspects . . . 127
4.2 Penetrated Aspects: Architecture and Content . . . 134
4.3 Consequences of Cognitive Penetration . . . 146
4.4 Defining Cognitive Penetrability of Perception . . . 153
4.4.1 Semantic Criterion . . . 154
4.4.1.1 Objections to the Semantic Criterion . . . . 157
4.4.2 Counterfactual Criterion . . . 159
4.4.2.1 Objections to the Counterfactual Criterion . 160 4.4.3 Causal Relation Criterion . . . 165
4.4.3.1 Objections to the Causal Relation Criterion 165 4.4.4 Informational Encapsulation Criterion . . . 168
4.4.4.1 Objections to the Informational Encapsula- tion Criterion . . . 170
4.4.5 The Informational Encapsulation Criterion (Refor- mulated) . . . 171
5 Content Cognitive Penetration 177 5.1 Psychological Studies and Content Cognitive Penetration . . 191
5.2 Content Cognitive Penetration of Late Vision . . . 198
5.3 Content Cognitive Penetration of Early Vision . . . 202
5.3.1 Synchronic and Diachronic Content Cognitive Pene- tration . . . 213 6 Architectural Cognitive Penetration 217
6.1 Cognitive Penetration and Neural Plasticity: The Philosoph-
ical Debate . . . 218
6.2 Perceptual Learning and Neural Plasticity . . . 222
6.3 Perceptual Learning Study . . . 225
6.4 Attention . . . 231
6.4.1 Load Theory of Attention . . . 235
6.4.2 Cognitive Control on Attention in Perceptual Learning237 6.4.3 Cognitive Control on Attention in the Target Study . 243 6.5 Cognitively Guided Attention Influences Early Vision . . . . 246
6.6 Architectural Cognitive Penetration . . . 249
7 Predictive Coding 255 7.1 Predictive Coding . . . 257
7.1.1 The Predictive Coding Model . . . 263
7.2 Cognitive Penetration of Perception and Predictive Coding . 270 7.3 Beneficial and Pernicious Cognitive Penetration . . . 275
8 Cognitive Penetration, Modularity, and Perceptual Justi- fication 287 8.1 Cognitive Penetration of Early Vision and Modularity . . . . 294
8.2 Cognitive Penetration and Theories of Perceptual Justification302 Appendices 309 A Content Cognitive Penetration . . . 309
B Architectural Cognitive Penetration . . . 310
References 311
I would like to express my gratitude to many people for their help and support during the years of my Ph.D. First of all, my deepest gratitude is for my supervisor, Pascal Engel, who made me discover analytic philosophy during my years as a master student in Geneva. His help and constant support has been invaluable to accomplish this thesis. He has been always encouraging and pushing me further in my research. His incentive gave me the chance to discover a variety of research areas in philosophy. Pascal has always been available to help me, not only in academic matters, but also in my personal life. Above all, I must thank him for being so patient with me and this thesis.
I also owe special thanks to Fiona Macpherson for her supervision dur- ing almost two years at the University of Glasgow. Our long discussions, her insightful observations and criticism, but also disagreement with my view, were decisive for the topic discussed in this thesis. Fiona’s supervi- sion deeply influenced the present work and my way to tackle philosophical issues.
There is another philosopher to whom I am in debt, Santiago Echev- erri. The main arguments of this thesis were the result of exciting and exceptionally valuable exchanges during our long conversations together.
His expertise, comments and advice influenced every line of this thesis (al- though I am the only responsible for all the problems it could have). My greatest gratitude to his friendship and precious help.
I am specially grateful to other philosophers who have greatly influ- enced the present work. In alphabetic order: Umut Baysan, Antonio
Ben´ıtez L´opez, Philipp Blum, Andy Clark, Jennifer Corns, Robert Cowan, Julien Dutant, Davide Fassio, Emilio Garc´ıa Buend´ıa, Giovanni Gellera, Jack Lyons, Kevin Mulligan, Athanassios Raftopoulos, Barry Smith, Mar- tin Smith, Michael Sollberger, Marcel Weber, and an anonymous referee of dialectica. I am thankful to them for their support and help, stimulating conversations, for reading and commenting on early chapters, and specially for invaluable comments and feedback.
I would also like to thank two scientists, Petra Vetter and Sophie Schwartz, for assisting me in the understanding of scientific studies as well as recommending me some of the scientific literature discussed in the present work.
I addition, I am specially thankful to the members of Episteme (the epistemology research group) in the Department of Philosophy at the Uni- versity of Geneva, such as Arturs Logins, Anne Meylan and Jacques Vollet and to other members of this department. I am also grateful to the par- ticipants of the Postgraduate Seminar in the Department of Philosophy at the University of Glasgow (in which I spent two years as a visiting student, 2012-2014) and to the members of this department. Part of the material in this thesis was also presented in the III Workshop on Philosophy and Cognitive Science, University of Buenos Aires, in 2012; I am thankful to the organizers Diego Lawler, Diana P´erez, Liza Skidelsky and Joel Lorenzatti and to the participants for very interesting discussions.
Other people I like to thank are Dominique Janain and Olivier Frutiger for being so helpful and professional. Furthermore, particularly thanks to Pierre Moiroud for his help and support all along these Ph.D. years, and of course to Gabriele Talotti.
The present work has been supported by many institutions: the Uni- versity of Geneva; the Swiss National Science Foundation, which founded my studies during the academic years 2009-2013, with the project “Per- ceptual Warrant, Entitlement and A Priori Knowledge” (2009-2013), and from which I received a scholarship to study nine months in 2012 at the University of Glasgow; and two scholarships Th´eodore Flournoy (2009) and
Philibert Collart (2013).
It would not have been possible to write this doctoral thesis without the help and support of all the people and institutions mentioned here.
Tambi´en me gustar´ıa agradecer a mis amigos y familia. Ellos son los que m´as sufrieron las consequencias de esta tesis. Durante los ´utlimos a˜nos no les prest´e la atenci´on que ellos se merecen.
This thesis defends the cognitive penetration of perception. Cognitive penetration can be roughly defined as those cognitive influences on per- ceptual systems which have consequences for the epistemic status of the subject. I will focus my attention mainly in the visual system and show that cognitive penetration occurs in early and late vision. The results of this thesis have consequences for the modularity of mind and epistemic theories of perceptual justification.
Chapter 1 gives a general introduction to cognitive penetration of per- ception and its consequences. In chapter 2, I will examine the different stages of the visual process, to wit, early and late vision, and I distinguish them from cognition. I will also explicate that the early visual system is defined as a module whose primary characteristic is to be informationally encapsulated or impenetrable from other systems, namely cognition. Subse- quently, I analyse the kind of properties the visual system is able to process.
I finish the chapter with the general hypothesis I will develop throughout my thesis: vision depends on a visuo-motor system capable of processing low-level properties whose earliest level of processing is cognitively encap- sulated. These characterisation will be reviewed in the last chapter, where I will show that early vision is cognitively penetrable and suggest that it might process high-level properties.
I will analyse, in chapter3, the two main types of cognitive penetration discussed in the literature, i.e., cognitive penetration of early and late vision.
Moreover, I will scrutinize three different accounts of cognitive penetration:
cognitive penetration of perceptual experience, of perceptual content, and
of content-independent mechanisms. At the end of that chapter, I briefly explain why all these forms of cognitive influences count as cognitive pen- etration of perception, namely, they all have epistemic consequences. In section 3.4, I introduce the debate between perceptual content and cogni- tive penetration of perception.
Chapter4has two parts. In the first part, I will distinguish between per- sonal and subpersonal states. I argue that personal states should be consid- ered as the triggers of the subpersonal cognitive mechanisms that eventually penetrate perceptual systems. I also explain how the penetrating process seems to occur. In the following section I distinguish architectural from con- tent cognitive penetration. Content and architectural cognitive penetration could be synchronic and diachronic and can occur in early or late vision.
The second part of chapter4 explores different definitions of cognitive pen- etration of perception: the semantic criterion, the counterfactual criterion, the causal relation definition, and the informational encapsulation criterion.
I conclude the chapter with a modified definition of the informational en- capsulation criterion which seems to satisfy two plausible desiderata: it is not unduly restrictive but is broad enough to include all forms of cognitive penetration discussed in chapter3.
Chapter 5 justifies the use of neuroscientific studies to demonstrate the existence of cognitive penetration of early vision. Content cognitive pene- tration of early vision is analysed in the empirical study by Gamond et al.
(2011). They tested whether (unconscious) learned associations between a facial trait and personality features can affect how subjects perceive some- one’s personality from their picture. I will argue that the results of this experiment show a form of content cognitive penetration of early vision.
Chapter 6 presents a perceptual learning (Schwartz et al. 2002) study which shows architectural cognitive penetration of early vision.1 In the experiment, cognitive influences on the early visual system caused structural
1The main arguments of this chapter appeared in the article “Cognitive Penetration, Perceptual Learning, and Neural Plasticity” published in dialectica 2014, 68 (1), pp.
63–95.
changes (neural reorganization) in the visual system.
In chapter7, I provide a theoretical framework to understand cognitive penetration, to wit, predictive coding theory. Predictive coding hypoth- esises that the brain is constantly predicting the near future to improve and facilitate perception. The cognitive penetration of perception can be therefore characterised as a prediction that is epistemically consequential for the visual system. This theoretical framework will allow us to define when cognitive penetration is beneficial or pernicious.
Finally, in chapter 8, I summarize the main results of this thesis and come back to modularity and perceptual justification. With regard to modularity, I briefly argue that although informational encapsulation from cognition fails in early vision, objectivity is preserved. I will also explain that only some externalist theories of perceptual justification, namely those which extend the justificatory process from the perceptual organ to the perceptual belief, are able to provide an account of the kind of justification necessary for perceptual knowledge.
1
Introduction
Contents
1.1 Cognitive Penetration . . . 6 1.2 Cognitive Penetration and Perceptual Justification . . . 10 1.3 Structure of the Thesis . . . 19
I look outside the window and see a garden, trees, flowers, birds and the sun shining intensely. I also hear birds chirping, and feel that the room is warm. I grasp my mug, smell the particular aroma of coffee, sip from it, and taste its bitter and strong flavour. All this information (what I see, hear, touch, smell, or taste) is presented by my senses in the form of perceptual experiences. Experiences seem to provide the evidence I need to form beliefs about the external world. For instance, the visual experience of a bird is the evidence I need to believe that there is a bird outside. If, in addition to
this evidence, other conditions are satisfied, I can know that there is a bird in the garden.
Perceptual knowledge has to satisfy certain necessary and sufficient con- ditions. According to the traditional definition which has its origins inPlato (Plato, 201d-210a), perceptual knowledge is defined as justified true belief.1 Believing is the first condition of this definition. In order to know something I have to believe it. However, believing is not enough to have perceptual knowledge. In addition, this belief has to be true. I could see something which looks like a bird, form the belief that a bird is outside, but, if there is no bird outside, my belief is false. I could have seen perhaps some flowers disposed in such a way that combined looked like a bird. In addition to a true belief, knowledge requires some form of justification. Without having any evidence, I could form the belief that there is a bird in the garden which happens to be true. But having a belief without any evidence (e.g., a visual experience of the bird or any other reason) would count just as a lucky guess. On this traditional picture, perceptual experiences are the evidence on which we base our perceptual beliefs. They justify our perceptual beliefs or form part of the process that justifies them.
Nowadays we know that having a justified true belief is not sufficient for perceptual knowledge. Gettier(1963) showed that we could have a justified true belief and still not know. For instance, I could look outside my window, see flowers particularly disposed which look like a bird and take them for a bird. The visual experience of what looks like a bird to me is the evidence on which I base my belief that there is bird in the garden. Unbeknownst to me there is in fact a bird behind a tree. In this scenario, all the necessary conditions of the classical definition of knowledge are satisfied: I have a perceptual experience (the evidence) on which I based my belief that there is a bird, my belief is true because there is a bird in the garden, but I do not know that there is a bird in the garden yet.
1Notice that the classic interpretation of perceptual knowledge is not the only one.
Williamson(2000, 42-ff) claims that knowledge is an unanalysable mental state. There are also conterfactual definitions of knowledge in terms of sensitivity (Nozick 1981) or safety (Sosa 1999,2007), and so on.
led philosophers to add, at least, a fourth or even more conditions to de- fine perceptual knowledge. These extra conditions involve either internalist or externalist requirements. Some examples are: being a psychologically normal person, having a well-functioning system, being in a non-Gettier scenario, being in the appropriate environment (e.g., visual perception is not reliable under water) and having good observational conditions (e.g., poor light conditions).2
The problem with these necessary and sufficient conditions is that their satisfaction is not sufficient yet for perceptual knowledge. According to them, a normal subject with visual and cognitive systems working properly in the appropriate scenario, with ideal observational conditions, will acquire perceptual knowledge. For instance, when I look at the bunch of flowers disposed in such a way that they look like a bird, I can properly perceive that they are flowers and form the a belief accordingly. However, there could be cases in which this definition of knowledge might fail. Imagine that someone tells me that this season there is a great amount of birds in the city. My belief that the city is full of birds leads me to form the belief that they will come to my garden. Now let’s assume that I am a normal subject with properly working systems sitting in my garden with ideal observational conditions. It could be the case that when I look at the bunch of flowers, my belief that birds are around and my desire to see some of them in my garden, influence my perceptual experience and I end up having a perceptual experience as of a bird there. Then, I form the belief that there is a bird in the garden based on this corrupted perceptual experience. However, unbeknownst to me, there is actually a bird behind the tree. In this example, my epistemic situation satisfies all the necessary and sufficient conditions for knowledge although I did not know that there is a bird in the garden. In spite of being in an appropriate environment,
2Two remarks are important here. First, this list is not exhaustive. And second, I am not discussing any specific theory of justification but just enumerating conditions which may be relevant for knowledge.
my background belief and desire about birds led my perceptual experience to misrepresent the bunch of flowers as a bird.
The influence of our cognitive states on our perceptual systems is known as the cognitive penetration of perception. Although the cognitive penetra- tion of perception represents a serious problem for perceptual justification and knowledge, it is only recently that analytic philosophers started to take it seriously. The focus of my thesis is cognitive penetration of perception.
1.1 Cognitive Penetration
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 consequences 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.
1.2 Cognitive Penetration and Perceptual Justification
Justification is some positive epistemic status that a proposition or a belief can have which makes them epistemically appropriate. It can be understood in two different ways: the epistemic status ofhaving justification
for believing or being justified in believing a proposition p, and justifying one’s belief that p. The latter involves one’s doing something to show that p, or to show that one’s belief is justified, or exhibit one’s justification. That is the activity of defending or giving reasons. Nonetheless, someone might be justified in believing that there is a chair in front of her when she sees the chair even though she has done nothing to show that there is a chair or to show that she is justified in believing so. The former is a state or condition the subject is in, not anything one does or any upshot thereof.
That refers to the property of being justified. (See, for instance, Alston (1985, 58; 1989a, chs. 1, 2, 3, 6); Audi (1993, 1993; 2011, 2); Pryor (2000, 521; 2005, 193-195); Steup (1996, 10).)3 The relevant form of justification for our purposes is having justification or being justified in believing.
There is another important distinction about justification. Someone might have justification for believing that there is a chair in front of her because she sees the object even though she does not believe anything about the chair. In addition, when she believes that there is a chair in front of her, she does not only have justification for her belief but moreover she could be justified in believing so. This example exhibits two different epistemic statuses of justification. The first one has to do with the justification of a proposition, that is, propositional justification; and the second has to do with the psychological state of believing — forming the belief itself —, i.e., doxastic justification. (For this distinction see Audi (2011, 2-3); Firth (1978a, 218-9; 1978b;1978c); Fumerton(2002, 206-7); Plantinga (1993, 95- ff, 183ff); Pryor (2005, 81-2).) Propositional justification is the epistemic status of having justification for believing a proposition. Having justification for believing is independent from one believing it or not. The justificatory property refers to the justification of a proposition: when a proposition is being justified. For instance, imagine a subject looking at a table but who does not form any belief about it. In these circumstances, the subject has propositional justification for believing that there is a table because she has
3Leite (2004) criticizes this distinction. He thinks that we cannot dissociate the activity of justifying from the fact of being justified.
some evidence that supports a potential belief about the table despite the fact that she does not believe it at the moment. Doxastic justification is the epistemic status of being justified in believing a proposition. It is a more demanding epistemic position than propositional justification because it implies not only that onehas justification for believing a proposition — that is, has evidence that supports a proposition —, but also that one believes the proposition based on adequate evidence. In sum, in the former case, the subject has justification for a proposition or the proposition is justified even though she does not form any belief about that. In the latter, the subject has justification for a belief or the belief is justified; she is justified in holding the belief.4 This difference could be also expressed regarding beliefs independently of the propositions distinguishing between the justifiability and the justifiedness of a belief. A belief could be justifiable (the subject could have the appropriate evidence for believing it) even though she does not believe it; and the belief is justified once she holds it on the right evidence (Lyons 2009, 22 and n. 3).
The kind of perceptual justification I will take into consideration in this thesis is doxastic justification, the epistemic and psychological state of believing. First of all, the amount of things we actually believe on the basis of the information provided by our senses is extremely little in relation to the amount of propositions we have justification for. Looking at a lawn, someone might be justified in believing that it has more than ten blades of grass per square foot, but also more than eleven, twelve, one hundred, and so on. The subject might also believe that there are fifteen blades of grass shorter than the largest one, or sixteen, or seventeen, and the like (Audi 2011, 3). We have an infinite amount of justification for believing propositions even if we actually believe an extremely limited number of them. Thus the relevant kind of justification for perceptual knowledge is doxastic justification, i.e., when the subject is justified in holding the belief she actually has on the basis of her senses. Propositional justification cannot explain perceptual
4Doxastic justification is what Feldman and Conee call “well-foundedness” (Conee and Feldman 2001a;Feldman and Conee 1985).
knowledge (neither knowledge in general) because knowledge requires belief, and propositional justification is justification of propositions, not of belief.
(See Comesa˜na(2010, 574).)
Theories of perceptual justification can be divided into internalist and externalist. Internalist theories maintain that the justification of percep- tual beliefs supervenes on the subject’s mental states; nothing outside the subject’s cognitive perspective can justify beliefs. Externalist theories hold, on the contrary, that the justification of perceptual beliefs depends at least partially on external elements to the subject’s mental states. The following quotations illustrate this contrast (see also Fumerton (2006, 54); Pollock (1999, 394); Pollock and Cruz (1999, 24)):
[I]t is internalism if and only if contingent factors external to the mind cannot make an epistemic difference.
[...]
Externalists characteristically hold that differences in justification can result from contingent non-mental differences, such as differing causal connections or reliability. (Conee and Feldman 2001b, 56) The internalist, on this view, maintains thatS’s knowing thatP, or having a justified belief that P, consists in S’s being in some inter- nal state. The externalist, by contrast, is one who is committed to the view that knowledge and justified belief at least involve external states. (Fumerton 1995, 60-61)
There is an important contrast in the above quotations. Fumerton is interested in doxastic justification while Conee and Feldman refer to propo- sitional justification. However, the previous descriptions exhibit the same characteristics: a theory is internalist if and only if all the elements needed for the justification of a perceptual belief are internal to the subject’s men- tal life; and it is externalist if any external feature to the subject’s ken can produce any epistemic difference.
Internalist and externalist theories can be divided into weak and strong
versions.5 Weak internalism holds that a subject’s perceptual beliefB is jus- tified if and only if she has a perceptual mental state e which epistemically supports B, and S forms the belief B on the basis of e. Weak internal- ism is the thesis that the justification of the subject’s belief is necessarily and sufficiently justified by the subject’s mental states, or evidence. Justi- fication superveness on mental states. Let’s label this view as ‘Internalist Mentalism’.6 The most well known version of Internalist Mentalism has been formulated by Earl Conee and Richard Feldman (2004; 2001b) under the label of “Evidentialism” but it is also supported by Huemer (2001);
Pryor (2000, 2004), and apparently by Moore (1939), among others. This form of mentalism is internalist because it does not require any externalist condition (e.g., reliabilism) (see, e.g., Pryor 2000, 531-532). And it is a weak form of mentalism because it does not demand any other requirement for justification than the epistemic relation holding between the perceptual state and the belief.
Strong internalism holds that a subject’s perceptual beliefB is justified if and only if she has a perceptual mental statee which epistemically supports B,S forms the beliefB on the basis ofe, andS has access to some adequate epistemic relation holding betweene andB. That is, in addition to form her belief on the basis of this perceptual state, she must have some access — be aware (grasp, understand, comprehend, believe) — to the relation holding between the experience and the belief. This is a strong form of internalism because it requires the subject to be aware that the experience (adequately or epistemically) supports her belief.7 Call this view Accessibilism. Such
5For a similar and more extensive enumeration of the following theories see, e.g., Lyons 2009, 37-42.
6Internalist Mentalism is known as “Mentalism” or “Evidentialism” (Conee and Feld- man 2001b;Feldman and Conee 2004), “Consciousness Internalism” (Alston 1989a, 233),
“Simple Internalism” (Pryor 2001, 104), “Internal State Internalism” (Fumerton 1995, 2006), “Mentalist Internalism” (Steup 2008), and it is also a form of “Dogmatism” (Pryor 2000). For a different approach about mentalism as neither internal nor external see Bergmann(2006, ch. 3).
7Other labels of Accessibilism in the literature are, for example: “Access internalism”
(Pryor 2001;Fumerton 1995,2006), “Accessibility Internalism” (Alston 1989a, 233;Steup 2008), “Internalism” (Bergmann 2006). Notice that this is only a representative form of internalist accessibilism. Other forms of accessibilism could demand access to the
a view is defended by Chisholm (1989); BonJour (2003); Fumerton (1995, 2006); Steup (2004), among others.
The difference between these two groups can be seen inAudi(1998, 227), BonJour (2003, 24; 2010, 364), Conee and Feldman (2001a, 55), Fumerton (1995, 62), Plantinga (1993, 6) and Steup (2004, 404-405). Consider the following quotations:
Accessibility Internalism (AI), according to which only that to which the subject has cognitive access in some specially strong form can be a justifier.
[...]
Consciousness Internalism (CI), according to which only those states of affairs of which the subject is actually conscious or aware can serve to justify. (Alston 1989a, 233)
Simple internalism: Whether one is justified in believing p super- venes on facts which one is in a position to know about by reflection alone.
[...]
Access Internalism: One always has ‘special access’ to one’s justifi- catory status. (Pryor 2001, 104-5)
Externalist views also come in weak and strong versions. According to the weakest view, a subject’s beliefB is justified if and only if she has a per- ceptual mental statee which epistemically supportsB,S forms the beliefB on the basis ofe, and there is an appropriate external relation (e.g., reliable process, proper function) between e and B. Let’s call this view Externalist Mentalism. This perspective is a weak externalism because justification de- pends on internal features (the subject perceptual experiences) as well as on external features (an appropriate external relation connecting the belief to the experience). This view is the most common one about epistemic justifi- cation. Weak externalism is found in process reliabilism, which states that a
reliability of the perceptual process.
process is reliable “only if it generally produces beliefs that are true” (Gold- man 1979a, 98), or only if the probability of forming true beliefs is very high (Alston 1989b, 232), or “has a high ratio of true to false beliefs” (Lyons 2011, 306) (see Dokic and Engel 2002, 27-35 and Engel 2007c, 153 for an anal- ysis). Reliabilist externalist mentalist theories are held by Alston (1983, 1988, 1989a, 1993, 2002, 2005); Comesa˜na (2010); Dretske (1981, 2000);
Engel (2007c); Goldman (2008); Peacocke (1992b, 2004); Pollock (1986);
Pollock and Cruz (1999); White (2006). Another theory included in this group is proper functionalism. For instance, Bergmann (2006, 133) claims that a subject’s belief B is justified if and only if the cognitive faculties producingB from the perceptual experience e are (a) functioning properly, (b) truth-aimed and (c) reliable in the environments for which they were designed, and the subject does not takeB to be defeated. This account is held by Bergmann(2004b,a, 2006);Burge(1993, 2003,2010) andGraham (2011,2012).
Finally, there is strong externalism, a radical externalist view which maintains that a subject’s belief B is justified if and only if the belief B has been formed by an appropriate external process (e.g., reliable process, proper function). In other words, radical externalism denies that percep- tual experiences are necessary for justification. In the same conditions, the beliefB of a normal subject with a perceptual statee and the belief B of a blindsighted subject with no perceptual experience will be equally justified if they are produced by reliable processes. In this group I include all exter- nalist accounts which hold either that perceptual evidence does not always play a role in justification, or plays no role in justification. For instance, Plantiga’s proper functionalist account is formulated in terms of warrant:
having a warranted true belief is equivalent to knowledge. The subject’s beliefB is warranted if and only if the cognitive faculties producingB from the perceptual experience e are (a) functioning properly, (b) truth-aimed, and (c) reliable in the environments for which they were designed, and (d) the cognitive environment in which B is produced is sufficiently similar to the one for which the subject’s faculties were designed (Plantinga 1993,
19; see also Plantinga 1993, 46-7). Let’s label this approach Radical Ex- ternalism. Radical externalism is exemplified by some reliabilist theories (Goldman 1979b, 1986;Lyons 2005, 2008, 2009) and some forms of proper functionalism (Plantinga 1993, 2000).
These different groups of theories can be represented in the following table:
Theses of EJ weak strong
Internalism Internalist Mentalism Accessibilism
Externalism Externalist Mentalism Radical Externalism
The first three kinds of theories presented — i.e., accessibilism (strong internalism), internalist mentalism (weak internalism), and externalist men- talism (weak externalism), — are what Lyons (2009) calls ‘experientialist theories of perceptual justification’. Experientialism is the thesis that all justified beliefs have grounds, i.e., evidential justifiers. In the case of per- ceptual justification, the evidence is the perceptual experience (Lyons 2009, 29-30). On the contrary, radical externalism (strong externalism) is a non- experientialist theory. It does not require perceptual evidence to account for perceptual justification.
The kind of perceptual justification I am interested in is one that is nec- essary for knowledge. There are some philosophers who argue that some forms of perceptual justification, namely internalists, are not required for knowledge (Greco 2005). And there are those who think that, although internalist justification is not necessary for knowledge, it is nevertheless an interesting concept (e.g., Engel (1992);Wolterstorff (2005)). (See Steup (2004, 405).) I will rather interpret each of the previous theories as accounts of perceptual justification which, according to their advocates, are neces- sary for perceptual knowledge. For instance, Steup (2004), who holds an internalist accessibilist account, states that “there are those — and I count
myself among them — who view internalist justification to be of epistemo- logical interest, perhaps not exclusively but certainly primarily, because it is a necessary condition of knowledge” (Steup 2004, 405). Other theorists defend similar views (BonJour 2003; Fumerton 2006). About internalist mentalism Pryor (2000, 520) points out “the dogmatist about perceptual knowledge adds the further claim that this justification you get merely by having an experience as of p can sometimes suffice to give you knowledge thatp is the case”. Feldman largely defends that internalist justification is necessary for knowledge (Conee and Feldman 2001a; Feldman and Conee 1985;Feldman 2005).
The cognitive penetration of perception represents a problem for all the previous theories of perceptual justification. Several philosophers seem to adopt the view that perceptual experiences are exclusively produced by an isolated and bottom-up perceptual process. For instance, Berm´udez (1995); Bergmann (2006, 2013); Brogaard (2013); BonJour (2003, 77-96);
Burge(1993, 2003); Dretske (2000); Huemer (2001, 99-103); Markie (2005, 2006, 2013); McDowell (1998); McGrath (2013) Peacocke (1992b, ch. 3);
Pryor(2000, 540-541);Steup(2004). From this perspective, perceptual jus- tification refers to the transition from experiences (produced by an isolated perceptual system) to perceptual beliefs based on the previous states. Expe- rientialist accounts of justification (internalism and weak externalism) based on the prior interpretation of the perceptual process do not seem to be able to deal with cognitive penetration. Because these theories do not take into consideration the etiology of perceptual experiences, they are not capable of distinguishing between good and bad cases of cognitive penetration. The subject will be equally justified in good and bad cases of cognitive penetra- tion. Therefore, these theories do not account for the kind of justification necessary for perceptual knowledge.
Externalist theories of perceptual justification (externalist mentalism and radical externalism) are also undermined by cognitive penetration. Cer- tain cognitive influences in, e.g., perceptual learning, might increase the reliability of the visual system (Kellman and Garrigan 2009; Lyons 2011,
300) but others might also deteriorate its accuracy (see, e.g., Mednick et al.
2005).
Although cognitive penetration constitutes a problem for both external- ist mentalism and radical externalism, it is possible to reformulate them in such a way that they can deal with the phenomenon. For example, some weak externalists argue that the reliable or proper functionalist justifica- tory process does not begin in the perceptual experience but also includes its etiology. Thus, justification is a process which extends from the per- ceptual organ though the perceptual experience to the belief. A corrupted perceptual experience will involve the failure of the justificatory process.
Similarly, the strong externalist may argue that the justificatory process goes from the organ to the perceptual belief. If cognitive penetration influ- ences the reliability of the system the belief produced will not be justified.
In sum, the consequences of cognitive penetration on different theories of perceptual justification will be briefly examined in the last chapter. Al- though most theories of epistemic justification are threatened by cognitive penetration, there seem to be two groups capable of providing an account of justification which can deal with cognitive penetrability: externalist men- talism and radical externalism. Nevertheless, I will not provide any positive theory of perceptual justification.
Let’s present next the structure of this thesis.
1.3 Structure of the Thesis
In chapter 2 I will examine the different stages of the visual process, to wit, early and late vision, and I distinguish them from cognition. I will explain that early vision seems to be a process which lasts for about 100-120 ms after stimulus presentation, which produces primitive visual outputs (2- and 3-dimensional object representations). Late vision is the process which starts immediately after early vision and lasts approximately 200 to 300 ms post-stimulus onset. The process ends when the perceptual information becomes consciously available to the subject, to wit, the perceptual experi-
ence. I will also explicate that the early visual system is defined as a module whose primary characteristic is to be informationally encapsulated or im- penetrable from other systems, namely cognition. The modularity of vision includes both early vision and motor functions. Subsequently, I analyse the kind of properties the visual system is able to process. I finish the chap- ter with the general hypothesis I will develop throughout my thesis: vision depends on a visuo-motor system capable of processing low-level properties whose earliest level of processing is cognitively encapsulated. These charac- terisation will be reviewed in the last chapter, where I will show that early vision is cognitively penetrable and suggest that it might process high-level properties.
I will analyse, In chapter3, the two main types of cognitive penetration discussed in the literature, i.e., cognitive penetration of early and late vision.
Moreover, I will scrutinize three different accounts of cognitive penetration:
cognitive penetration of perceptual experience, of perceptual content, and of content-independent mechanisms. Cognitive penetration of perceptual experience designates the cognitive effects on perceptual content that nec- essarily have an impact on the content of perceptual experiences. Cognitive penetration of perceptual content refers to higher influences on operations responsible for perceptual content regardless whether these changes are or not reflected in the perceptual experience. These modulations can affect, for instance, the perceptual content intended for action which does not need to be consciously accessible. Moreover, there is cognitive penetration of content-independent processes. This case could be observed in cognitive guidance of motor functions. At the end of that chapter, I briefly explain why all these forms of cognitive influences count as cognitive penetration of perception: they all have consequences for perceptual justification. In sec- tion 3.4, I introduce the debate between perceptual content and cognitive penetration of perception.
Chapter4has two parts. In the first part, I will distinguish between per- sonal and subpersonal states. I argue that personal states should be consid- ered as the triggers of the subpersonal cognitive mechanisms that eventually
penetrate perceptual systems. I also explain how the penetrating process seems to occur. In the following section I distinguish architectural from content cognitive penetration. Architectural cognitive penetration refers to cognitive influences which affect the way the visual system behaves or processes perceptual content. Content cognitive penetration denotes higher effects that add, modify, or substitute any piece of information in percep- tual content. Content and architectural cognitive penetration could be syn- chronic and diachronic and can occur in early or late vision.
The second part of chapter 4 explores different definitions of cogni- tive penetration of perception: Pylyshyn’s semantic criterion, Siegel’s and Macpherson’s counterfactual criterion, Stokes’ causal relation definition, and finish with the informational encapsulation criterion proposed by Wu.
I conclude the chapter with a modified definition of the informational en- capsulation criterion which seems to satisfy two plausible desiderata: it is not unduly restrictive but is broad enough to include all forms of cognitive penetration discussed in chapter 3.
Chapter 5 justifies the use of neuroscientific studies to demonstrate the existence of cognitive penetration of early vision. Content cognitive pene- tration of early vision is analysed in the empirical study by Gamond et al.
(2011). They tested whether (unconscious) learned associations between a facial trait and personality features can affect how subjects perceive some- one’s personality from her picture. I will argue that the results of this experiment show a form of content cognitive penetration of early vision.
Chapter 6 presents a perceptual learning (Schwartz et al. 2002) study which shows architectural cognitive penetration of early vision.8 In the ex- periment, cognitive influences on the early visual system caused structural changes (neural reorganization) of the visual system. The highly demanding visual task required cognitively guided attention on early vision. Cognitive guidance is responsible for the selection of the relevant object properties by
8The main arguments of this chapter appeared in the article “Cognitive Penetration, Perceptual Learning, and Neural Plasticity” published in Dialectica 2014, 68 (1), pp.
63-95.
stimulating the neurons in the visual cortex which encoded these properties.
The constant repetition of the same task eventually produced neural reor- ganization in the visual system. These effects are architectural because they modulated specific areas of the visual system making them more sensitive to the trained properties.
In chapter 7, I provide a theoretical framework to understand cognitive penetration, to wit, predictive coding theory. Predictive coding hypothe- sises that the brain is constantly predicting the near future to improve and facilitate perception. The cognitive penetration of perception can be there- fore characterised as a prediction that is epistemically consequential for the visual system. This theoretical framework will allow us to define when cog- nitive penetration is beneficial or pernicious: good cases are determined by the success of the predictive process, while bad cases are those in which there is prediction failure. Furthermore, I conclude that good and bad cases of cognitive penetration should be determined in terms of the reliability of the predictive process as well as the well-functioning of the system and the perceptual environment.
Finally, in chapter 8, I summarize the main results of this thesis and come back to modularity and perceptual justification. With regard to mod- ularity, I briefly argue that although informational encapsulation from cog- nition fails in early vision, objectivity is preserved. Cognitive penetration is not purposeless and capricious but rather goal-directed, slow, and fol- lows the needs of the organism to ensure its survival. This pace of changes preserves reliability and objectivity. As I have anticipated in this introduc- tion, I will also explain that only some externalist theories of perceptual justification, namely those which extend the justificatory process from the perceptual organ to the perceptual belief, are able to provide an account of the kind of justification necessary for perceptual knowledge.
Let’s turn now to the explanation of vision.
2
The Visual System
Contents
2.1 Visual and Cognitive Systems . . . 26 2.1.1 Early Vision . . . 28 2.1.2 Late Vision . . . 36 2.1.3 The Cognitive System . . . 42 2.2 Modularity . . . 48
2.2.1 Informational Encapsulation of the Visuo- Motor System . . . 53 2.3 Visual Properties. . . 60 2.3.1 Properties Represented in Early Vision . . . 64 2.4 Hypothesis Adopted . . . 68
Perceptual systems (e.g., visual and auditory) are typically regarded as
composed of central and peripheral subsystems, and having early and a late stages of processing.
Cognitive penetrability of perception, broadly understood, refers to the influence that the cognitive system has on perceptual systems. Penetrating states could be knowledge, beliefs, intentions, expectations, but also desires, moods, feelings, and so on.1
In order to spell out the cognitive penetration of perception it is neces- sary to explain how we should understand perceptual processing, in order to determine which subsystem is cognitively influenced and at which level of processing, to wit, early or late vision. In this thesis, I will focus my at- tention principally on the visual system (understood as the conjunction of early and late vision, and visuo-motor mechanisms). There are several rea- sons why I decide to consider mainly the visual system in this thesis. First, vision is a very well studied field which provides very rich empirical data essential for the debate on cognitive penetration. Second, the arguments on this thesis upholding cognitive penetration will be directly based on recent neuroscientific evidence and, as far as I know, empirical studies on other sense modalities are not as detailed as they are on vision. The amount and variety of studies on vision together with their highly detailed data repre- sent an essential instrument for this thesis. Finally, in this chapter I will meticulously scrutinize vision; a similar analysis of another sense modality would have increased the length of this thesis unnecessarily. Nonetheless, although this dissertation is mainly focused on cognitive penetration of the visual system, I will make reference as much as possible along the next chapters to empirical studies susceptible of showing cognitive penetration of other senses. Furthermore, I am convinced that the consequences of my research — to wit, that the entire visual system is cognitively penetrated — can be extended to other sense modalities (e.g., auditory, tactile, but also
1This definition of cognitive penetrability is broadly construed, it refers not only to cognitive states but also to affective states such as emotions, moods, and feelings (see, e.g.,Lyons 2011, 290;Siegel 2012, 201;Siegel 2013c, 698, 719-720;Siegel and Silins 2014, 30;Macpherson 2012, 27;Stokes 2012.)
Three main aspects need to be scrutinized about the perceptual system in order to understand the debate on cognitive penetration (see, for instance, Macpherson 2012, 29-33):
1. How to characterize the visual system? Is visual perception an early or a late level of visual processing? Is the visual processing distin- guishable from cognition?
2. How does the visual system process information? Is the visual pro- cessing of information isolated from other systems, and thus informa- tionally encapsulated? Or does it necessitate the intervention of other systems (perceptual, motor or cognitive) in order to process visual information?
3. Which properties are represented by the visual system? Does percep- tion represent low-level properties such as colour, shape, size, bright- ness, and the like, or it also represents high-level properties such as pine trees, tables, faces, and so on?
In order to answer that first group of questions in section 2.1 I will analyse the nature of the visual and the cognitive systems, their levels of processing and interactions. I will characterise the visual system as a visuo- motor system composed of three subsystems: two central, early and late vision, and one peripheral, motor. I will also analyse cognition (2.1.3).
Next, I will focus my attention on modularity, and argue that at some level of processing the visual system is informationally encapsulated (section 2.2). This will respond to the second interrogation. Finally, I will scrutinize which kinds of properties are processed and represented in visual perception (section 2.3). At the end of the chapter (section 2.4), I will spell out the working hypothesis that I will adopt along this thesis. Let’s begin with the analysis of the visual system and stages of processing.
2Having clarified this, hereafter, when I discuss cognitive penetration I refer to cog- nitive penetration of visual perception.
2.1 Visual and Cognitive Systems
Vision or visual perception is the process which begins with the compu- tation of a physical stimulus on the retina and finishes with the generation of a perceptual experience. This process could be essentially separated in two levels of processing: early vision and late vision (Cavanagh 2011;Fodor 1983, 2000; Hayward and Tarr 2005; Hildreth 1987; Hildreth and Ullman 1989;Marr 1982;Pylyshyn 1984, 1999a, 2003;Raftopoulos 2001c, a,2009a;
Rensink 2000a,b; Ullman 1996; Wagemans et al. 2005).
Hildreth and Ullman (1989) distinguish between three levels of visual processing: low-, intermediate-, and high-level.3 The low-level stage of the processing is characterized by a bottom-up mode of information treatment.4 At this stage of processing visual information occurs in parallel — i.e., visual operations happen across the entire visual field — and the properties pro- cessed are, e.g., edge detection, binocular stereopsis, depth, shade, colour, texture, and movement. (Hildreth and Ullman 1989, 583, 610-611)
The intermediate visual level computes shape identification (geons)5, object manipulation, locomotion, and navigation through the environment, and includes processes extracting shape properties and spatial relations.
These processes cannot be entirely stimulus-dependent and necessitate the interaction of lower and higher visual areas. An object could be described in different ways, some of these descriptions can be more useful than oth- ers. The same visual scene will be processed differently if in one case the task concerns objects’ size (shape properties) and in another circumstance distance between objects (spatial relations). The process depends on use- fulness rather than on validity (Hildreth and Ullman 1989, 610). Then, the relevant representation of the visual scene at the intermediate-level vi- sion cannot be entirely stimulus-driven, but is instead task dependent or
3For a similar and contemporary explanation of visual processing seeCavanagh(2011).
4Bottom-up in this particular case refers to the sort of processing which only depends on the visual stimulus, and is independent of the task to be performed.
5Geon representations are simple 2- or 3-dimensional forms such as edges, lines, circles, rectangles, triangles, or cylinders, cubes, wedges and cones corresponding to the simple parts of an object.
top-down visually dependent (Hildreth and Ullman 1989, 610-615).6
High-level vision identifies and categorizes objects in the visual world.
The process necessitates of top-down cognitive influences to match the rep- resentation generated by the visual system with internal representations of objects stored in long-term memory (Hildreth and Ullman 1989, 610-620).
The contrast between low- and intermediate-level vision, on the one hand, and high-level vision, on the other hand, is that, while the former are not cognitively influenced (e.g., by memory), the latter intimately relies on it:
“[t]he process of object recognition is therefore different from processes of intermediate and low-level vision in that it is more intimately related to the problems of memory organization, retrieval, expectations, and reasoning”
(Hildreth and Ullman 1989, 610, 616-617). Thus, high-level vision involves cognitive influences.
Hildreth’s and Ullman’s (1989) low- and intermediate-level vision ap- proximatively corresponds to the definition of the visual system given by Marr(1982) — what he calls early vision. Marr decomposes and character- izes early vision in three stages of processing with different degrees of ab- straction that combined reconstruct the visual scene (Marr(1982, 136-138);
see alsoEngel(1996, 225-226) for a presentation): a primal sketch which rep- resents visual information about the two-dimensional image, mainly changes in intensity and geometrical organization; a 21/2-D sketch which describes the orientation and depth of surfaces, and detects contours and discontinu- ities from the viewer-centred view point; and a 3-D sketch which depicts the spatial organization of volumetric characteristics from the object-centred perspective. In Marr’s caracterization, Hildreth’s and Ullman’s (1989) high- level vision corresponds to a form of late vision.
To sum up, we can distinguish between two levels of visual processing.
Early vision which strictly depends on the interaction between bottom- up incoming visual information and processes happening within the visual
6Top-down influences at this level come from the visual system itself, i.e., they are vi- sual top-down influences or, as some authors define them ‘lateral or horizontal influences’
(Cavanagh 2011, 1538;Pylyshyn 2003, 68;Raftopoulos 2009a, 51, 274).
system. As a result this process delivers geon representations. And late vision, a stage in which the visual process governing object recognition and categorization depends on top-down cognitive influences.
In what follows I will spell out early and late vision.
2.1.1 Early Vision
The visual system is defined by some scientists (Pylyshyn 1980, 1984, 1999a, 2003) and philosophers (Fodor 1983,1988,2000;Raftopoulos 2001c, a, 2009a, 2011, 2014a) as early vision. Accordingly, even though visual perception refers to the processing of information going from the retina up to the generation of a perceptual experience, what they call ‘visual sys- tem’ is restricted to early vision in the terms of Marr’s (1982) definition
— i.e., low- and intermediate-level vision in Hildreth and Ullman (1989).
Pylyshyn(2003, 50) claims “within the broad category of what we call ‘vi- sion’ is a highly complex information processing system, which some have called ‘early vision,’ that functions independently of what we believe” (see also Pylyshyn 1999a, 342). Raftopoulos (2009a, 51) labels it simply as
“perception”.7
The early visual system is considered as isolated from cognition: the computation of the visual input necessary to produce an output is indepen- dent from mnemonic influences (Fodor 1983, 64, 70-71; Hildreth and Ullman 1989, 610, 616-617; Pylyshyn 1999a, 361; 2003, 134-136). Pylyshyn (2003, 136) argues that “the early-vision system could encode any property whose identification does not require accessing general memory”. (I analyse this claim in section2.2.)
The subsequent process is cognition which is composed of late vision and cognition properly speaking.8 Higher visual and non-visual processes
7Hereafter the term ‘early vision’ and ‘early visual system’ will be used as synonyms.
8Late vision is the stage of visual processing which interacts with memory; a process necessary to recognize and categorize objects. Cognitionproperly speaking refers to the stage in which the cognitive system can perform all its operations independently from perceptual processes. This is a purely cognitive stage (this includes beliefs, desires, feelings, and so on). See section2.1.2.
