Athanassios RaftopoulosUniversity of Cyprus, Dept. of Psychology

raftop@ucy.ac.cy

Athanassios RaftopoulosUniversity of Cyprus, Dept. of Psychology

raftop@ucy.ac.cy

THEORY LADENNESS OF PERCEPTION, CONCEPTS, AND

COGNITIVE IMPENETRABILITY OF PERCEPTION

THEORY LADENNESS OF PERCEPTION, CONCEPTS, AND

COGNITIVE IMPENETRABILITY OF PERCEPTION

In this paper I argue that since there is evidence that there exists a stage of visual perception, namely early vision, which is cognitively impenetrable and has non-conceptual content (NCC), and since I take cognitive penetrability, conceptual encapsulation, and theory ladenness as coextensive, the cognitive impenetrability of early vision entails that the content of early vision is theory neutral.

In this paper I argue that since there is evidence that there exists a stage of visual perception, namely early vision, which is cognitively impenetrable and has non-conceptual content (NCC), and since I take cognitive penetrability, conceptual encapsulation, and theory ladenness as coextensive, the cognitive impenetrability of early vision entails that the content of early vision is theory neutral.

“Cognitive” encompasses activities involving propositional attitudes. Since concepts are construed as constant, context independent, and freely repeatable elements that figure constitutively in propositions cognition necessarily involves concepts.

Concepts are embedded in frameworks; wherever there are concepts there are conceptual frameworks. Hence, cognitive states have conceptual contents and the issue of the cognitive impenetrability of perception is the problem of whether the contents of perceptual states are influenced by one’s concepts.

“Cognitive” encompasses activities involving propositional attitudes. Since concepts are construed as constant, context independent, and freely repeatable elements that figure constitutively in propositions cognition necessarily involves concepts.

Concepts are embedded in frameworks; wherever there are concepts there are conceptual frameworks. Hence, cognitive states have conceptual contents and the issue of the cognitive impenetrability of perception is the problem of whether the contents of perceptual states are influenced by one’s concepts.

I have explained why “cognitive penetrability of perception” and “conceptual effects on perception” should be treated as coextensive.Conceptual frameworks constitute theories (in a broad sense of the term and not necessarily in a strict scientific sense, since there is no requirement that conceptual frameworks be free of contradictions), and thus, the cognitive penetrability of perception, by implicating the conceptual apparatus, also signifies the “theory-ladenness of perception”.

I have explained why “cognitive penetrability of perception” and “conceptual effects on perception” should be treated as coextensive.Conceptual frameworks constitute theories (in a broad sense of the term and not necessarily in a strict scientific sense, since there is no requirement that conceptual frameworks be free of contradictions), and thus, the cognitive penetrability of perception, by implicating the conceptual apparatus, also signifies the “theory-ladenness of perception”.

I have proposed a definition of nonconceptual content (NCC) according to which X is in a representational state S with NCC P, if X has (or is being disposed to have) a content that is (directly) causally connected in a certain way to instantiated Phood independent of the cognitive states of X. The content P of state S is independent of the content of the cognitive states of X iff the contents of the cognitive states do not enter into P, in that there is not an epistemic relation between the conceptual content and the content of the perceptual state. In this case, the content of the perceptual state is cognitively impenetrable. Hence, NCC is the content of perceptual states that are cognitively impenetrable (or conceptually encapsulated).

I have proposed a definition of nonconceptual content (NCC) according to which X is in a representational state S with NCC P, if X has (or is being disposed to have) a content that is (directly) causally connected in a certain way to instantiated Phood independent of the cognitive states of X. The content P of state S is independent of the content of the cognitive states of X iff the contents of the cognitive states do not enter into P, in that there is not an epistemic relation between the conceptual content and the content of the perceptual state. In this case, the content of the perceptual state is cognitively impenetrable. Hence, NCC is the content of perceptual states that are cognitively impenetrable (or conceptually encapsulated).

Early vision includes a feed forward sweep (FFS) of signal transmission in which signals are transmitted bottom-up and which lasts, for visual areas, for about 100 ms, and a stage at which there lateral and recurrent connections between neurons allow recurrent processing.

This recurrent processing, which starts at about 80 ms after stimulus onset, is restricted within visual areas and does not involve signals from cognitive areas. Lamme (2003) calls it local recurrent processing (LRP). LRP culminates at about 120-130 ms. After that period, signals from higher executive centers including mnemonic and executive. This is the stage of late vision.

Early vision includes a feed forward sweep (FFS) of signal transmission in which signals are transmitted bottom-up and which lasts, for visual areas, for about 100 ms, and a stage at which there lateral and recurrent connections between neurons allow recurrent processing.

This recurrent processing, which starts at about 80 ms after stimulus onset, is restricted within visual areas and does not involve signals from cognitive areas. Lamme (2003) calls it local recurrent processing (LRP). LRP culminates at about 120-130 ms. After that period, signals from higher executive centers including mnemonic and executive. This is the stage of late vision.

The thesis of cognitive impenetrability of early vision says that cognition only affects perception by determining where and to what attention is focused. It does not in any more direct way alter the contents of perceptions so that they be logically/epistemically connected to the content of beliefs, expectations, and so on. By not affecting directly the contents of early vision, one’s cognitive states do not determine the way that person perceives the visual scene. Thus, cognition affects perception only when a perceptual system’s content is altered in a way that makes it bear some logical relation to the contents of one’s cognitive states.

The thesis of cognitive impenetrability of early vision says that cognition only affects perception by determining where and to what attention is focused. It does not in any more direct way alter the contents of perceptions so that they be logically/epistemically connected to the content of beliefs, expectations, and so on. By not affecting directly the contents of early vision, one’s cognitive states do not determine the way that person perceives the visual scene. Thus, cognition affects perception only when a perceptual system’s content is altered in a way that makes it bear some logical relation to the contents of one’s cognitive states.

When cognitive states affect directly perceptual states, their respective contents bear some epistemic relation and the perceptual content is conceptual content. The cognitive influences that operate either pre-perceptually or post-perceptually I call indirect causal influences on perceptual processing and states. They are distinguished from direct causal influences that affect perceptual processing itself. Only in the latter case do perceptual contents bear an epistemic relation to cognitive contents and are cognitively penetrated.

When cognitive states affect directly perceptual states, their respective contents bear some epistemic relation and the perceptual content is conceptual content. The cognitive influences that operate either pre-perceptually or post-perceptually I call indirect causal influences on perceptual processing and states. They are distinguished from direct causal influences that affect perceptual processing itself. Only in the latter case do perceptual contents bear an epistemic relation to cognitive contents and are cognitively penetrated.

if the phenomenal content of experiences is ‘causally penetrated’ by the content of cognitive states, then the contents are cognitively or conceptually penetrated.

The contents of experiences are ‘causally penetrated’ by the contents of cognitive states, if the causal explanation of how or why it is that the perceiver is in a state with this content as opposed to some other content, has to take into account not only the perceiver’s position and the environmental perceptual conditions, but also the cognitive abilities she possesses.

if the phenomenal content of experiences is ‘causally penetrated’ by the content of cognitive states, then the contents are cognitively or conceptually penetrated.

The contents of experiences are ‘causally penetrated’ by the contents of cognitive states, if the causal explanation of how or why it is that the perceiver is in a state with this content as opposed to some other content, has to take into account not only the perceiver’s position and the environmental perceptual conditions, but also the cognitive abilities she possesses.

It is also arguable that the phenomenal content of this experience is NCC in that it does not constitutively depend on conceptual content (Tye 1995, 140; 2000, 61). It follows that a state can have cognitively penetrated content and yet this content be NCC.

Thus, cognitive penetrability is not a necessary condition for NCC and the debate regarding cognitive (im)penetrability is orthogonal to the debate regarding the conceptual vs. nonconceptual character of the content of perception.

It is also arguable that the phenomenal content of this experience is NCC in that it does not constitutively depend on conceptual content (Tye 1995, 140; 2000, 61). It follows that a state can have cognitively penetrated content and yet this content be NCC.

Thus, cognitive penetrability is not a necessary condition for NCC and the debate regarding cognitive (im)penetrability is orthogonal to the debate regarding the conceptual vs. nonconceptual character of the content of perception.

Let the ambiguous figure be the duck/rabbit ambiguous figure and suppose that some cognitive state makes one focus attention at some point on an ambiguous figure and this focus makes one see a duck-like figure (the term ‘duck-like’ figure signifies the NCC of one’s visual experience of a duck, that is, what one perceives even if one does not possess the concept ‘duck’) as opposed to a rabbit-like figure.

In this case, the content of the cognitive state must be invoked in a causal explanation of what is the phenomenal content. According to the intuitive view, the content is cognitively penetrated.

Let the ambiguous figure be the duck/rabbit ambiguous figure and suppose that some cognitive state makes one focus attention at some point on an ambiguous figure and this focus makes one see a duck-like figure (the term ‘duck-like’ figure signifies the NCC of one’s visual experience of a duck, that is, what one perceives even if one does not possess the concept ‘duck’) as opposed to a rabbit-like figure.

In this case, the content of the cognitive state must be invoked in a causal explanation of what is the phenomenal content. According to the intuitive view, the content is cognitively penetrated.

The thesis of cognitive impenetrability as I construe it explicitly denies this possibility. What one chooses to attend to may be determined by cognitive factors. However, this type of modulation of neuronal activity by spatial attention consists of two contributions.

The first concerns the enhancement of P1 ERP waveform for stimuli at the attended location in extrastriate visual areas with a latency of 7-0-100 ms after stimulus onset. This is clearly an exogenous attentional factor since it is data-driven and not theory-driven. As such, it does not entail any sort of top-down conceptual influence on early visual processing.

The thesis of cognitive impenetrability as I construe it explicitly denies this possibility. What one chooses to attend to may be determined by cognitive factors. However, this type of modulation of neuronal activity by spatial attention consists of two contributions.

The first concerns the enhancement of P1 ERP waveform for stimuli at the attended location in extrastriate visual areas with a latency of 7-0-100 ms after stimulus onset. This is clearly an exogenous attentional factor since it is data-driven and not theory-driven. As such, it does not entail any sort of top-down conceptual influence on early visual processing.

Second, attending to a location may enhance the spontaneous firing rates of the neurons tuned to the attended location in extrastriate areas V2, V3/V3a, V4, in parietal regions, and in V1 before the presentation of the stimulus.

However, this effect does not determine what subjects perceive at that location because by enhancing the responses of all neurons tuned to the attended location independent of the neurons’ preferred stimuli it keeps the differential responses of the neurons unaltered and thus does not affect what it is perceived at that location.

Second, attending to a location may enhance the spontaneous firing rates of the neurons tuned to the attended location in extrastriate areas V2, V3/V3a, V4, in parietal regions, and in V1 before the presentation of the stimulus.

However, this effect does not determine what subjects perceive at that location because by enhancing the responses of all neurons tuned to the attended location independent of the neurons’ preferred stimuli it keeps the differential responses of the neurons unaltered and thus does not affect what it is perceived at that location.

Therefore, spatial attention does not constitute a direct causal effect on early vision and does not entail its cognitive penetrability. By determining focus, the content of a cognitive state indirectly determines the content of an early vision state and this is why concepts figure in a causal explanation of the percept.

However, this indirect kind of determination does not entail the cognitive penetrability of the phenomenal content, that is, it does not entail that the content bears some epistemic relation to the content of some cognitive states.

Therefore, spatial attention does not constitute a direct causal effect on early vision and does not entail its cognitive penetrability. By determining focus, the content of a cognitive state indirectly determines the content of an early vision state and this is why concepts figure in a causal explanation of the percept.

However, this indirect kind of determination does not entail the cognitive penetrability of the phenomenal content, that is, it does not entail that the content bears some epistemic relation to the content of some cognitive states.

Even if one grants that early vision is not cognitively penetrable and is, thus, conceptually encapsulated, one could argue that since learning affects the way one sees the world, some of our experiences are learned and form memories that are stored in visual memory. These memories contain conceptual elements that are somewhat built in the perceptual system and affect processing from its inception.

Thus, our experiences shape the way we see the world and this means that people with different experiences see the world differently. Moreover, concepts do affect early vision not in a top-down manner but by being built in it.

Even if one grants that early vision is not cognitively penetrable and is, thus, conceptually encapsulated, one could argue that since learning affects the way one sees the world, some of our experiences are learned and form memories that are stored in visual memory. These memories contain conceptual elements that are somewhat built in the perceptual system and affect processing from its inception.

Thus, our experiences shape the way we see the world and this means that people with different experiences see the world differently. Moreover, concepts do affect early vision not in a top-down manner but by being built in it.

Familiarity can affect visual processing in different ways. It may facilitate object identification and categorization, which are processes that take time since their final stage occurs between 300-600 ms as is evidenced by the P3 ERP wave form in the brain) and their earlier stage starts about 150 ms onset as is evidenced by wave forms that are elicited about 150 ms and are thought to be early manifestations of P3.

Familiarity is in general considered to intervene during the latest stage of object identification (300-360 ms) and its effects are considered to be post-sensory since they involve the cognitive levels of the brain at which semantic information and processing, both required for object identification and categorization, occur.

Familiarity can affect visual processing in different ways. It may facilitate object identification and categorization, which are processes that take time since their final stage occurs between 300-600 ms as is evidenced by the P3 ERP wave form in the brain) and their earlier stage starts about 150 ms onset as is evidenced by wave forms that are elicited about 150 ms and are thought to be early manifestations of P3.

Familiarity is in general considered to intervene during the latest stage of object identification (300-360 ms) and its effects are considered to be post-sensory since they involve the cognitive levels of the brain at which semantic information and processing, both required for object identification and categorization, occur.

These sorts of effects seem to pose a threat to the cognitive impenetrability of perception since they cannot be considered post sensory.

The threat would materialize should the classification processes either require semantic information to intervene or require the representations of objects in working memory to be activated since this would mean conceptual involvement too.

However, researchers agree that the early classification effects in the brain result from the feed forward sweep and do not involve top-down semantic information, nor do they require the activation of object memories.

These sorts of effects seem to pose a threat to the cognitive impenetrability of perception since they cannot be considered post sensory.

The threat would materialize should the classification processes either require semantic information to intervene or require the representations of objects in working memory to be activated since this would mean conceptual involvement too.

However, researchers agree that the early classification effects in the brain result from the feed forward sweep and do not involve top-down semantic information, nor do they require the activation of object memories.

The early effects of familiarity may be explained by invoking contextual associations (that is, target-context spatial relationships) that are stored in early sensory areas to form unconscious perceptual memories, which, when activated modify the feed-forward sweep of neural activity resulting in the facilitating effects mentioned above. This is a case of rigging-up the early visual processing; it is not a case of top-down cognitive effects on early vision.

The early effects of familiarity may be explained by invoking contextual associations (that is, target-context spatial relationships) that are stored in early sensory areas to form unconscious perceptual memories, which, when activated modify the feed-forward sweep of neural activity resulting in the facilitating effects mentioned above. This is a case of rigging-up the early visual processing; it is not a case of top-down cognitive effects on early vision.

The early effects may also be explained by appealing to the storage of configurations of properties of objects or scenes. Neurophysiological, psychological research, and computation modeling all suggest that what is stored in early visual areas are implicit associations representing fragments of objects and shapes, as opposed to whole objects and shapes.

Since the implicit associations can affect figure-ground segmentation, in view of the fact that figure-ground segmentation occurs early (80-100 ms) these associations must be stored in early areas and cannot be representations stored in, say, anterior IT, an area which is involved in working memory function. The earlier visual areas store object and shape fragments and not holistic figures and shapes.

The early effects may also be explained by appealing to the storage of configurations of properties of objects or scenes. Neurophysiological, psychological research, and computation modeling all suggest that what is stored in early visual areas are implicit associations representing fragments of objects and shapes, as opposed to whole objects and shapes.

Since the implicit associations can affect figure-ground segmentation, in view of the fact that figure-ground segmentation occurs early (80-100 ms) these associations must be stored in early areas and cannot be representations stored in, say, anterior IT, an area which is involved in working memory function. The earlier visual areas store object and shape fragments and not holistic figures and shapes.

The associations in early visual circuits reflect the statistical distribution of properties in scenes. The statistical differences in physical properties of different subsets of images are detected very early by the visual system before any top-down semantic involvement as is evidenced by the elicitation of an early deflection in the differential between animal-target and non-target ERP’s at about 98 ms (in the occipital lobe). The low-cues could be retrieved very early in the visual system by analyzing the energy distribution across a set of orientation and spatial frequency tuned channels. This suggests that the rapid image classification may rely on low-level or intermediate-level cues that act diagnostically and allow the visual system to predict the classification of images very fast.

The associations in early visual circuits reflect the statistical distribution of properties in scenes. The statistical differences in physical properties of different subsets of images are detected very early by the visual system before any top-down semantic involvement as is evidenced by the elicitation of an early deflection in the differential between animal-target and non-target ERP’s at about 98 ms (in the occipital lobe). The low-cues could be retrieved very early in the visual system by analyzing the energy distribution across a set of orientation and spatial frequency tuned channels. This suggests that the rapid image classification may rely on low-level or intermediate-level cues that act diagnostically and allow the visual system to predict the classification of images very fast.

Though this is possible, notice that these concepts do not play the role that concepts are usually thought to play in cognition.

First, they are not personal contents in the sense that one is not aware of them when they are employed in early vision. They are subpersonal informational processing contents. (Bermudez 1995)

Second, they can be used only in the processes of early vision and they are not available for cognitive tasks.

Third, they do not allow re-identification across times and contexts of the objects formed during early vision.

Fourth, they do not satisfy Evan’s (1982) generality constraint.

Though this is possible, notice that these concepts do not play the role that concepts are usually thought to play in cognition.

First, they are not personal contents in the sense that one is not aware of them when they are employed in early vision. They are subpersonal informational processing contents. (Bermudez 1995)

Second, they can be used only in the processes of early vision and they are not available for cognitive tasks.

Third, they do not allow re-identification across times and contexts of the objects formed during early vision.

Fourth, they do not satisfy Evan’s (1982) generality constraint.

Pylyshyn (2007, 52) calls them subpersonal concepts since, being inside encapsulated modules of early vision, they do not enter into general reasoning. Such concepts may be ‘codes for proximal properties involved in perception, such as edges, gradients, or the sorts of labels that appear in early computational vision’.

Pylyshyn (2007, 52) calls them subpersonal concepts since, being inside encapsulated modules of early vision, they do not enter into general reasoning. Such concepts may be ‘codes for proximal properties involved in perception, such as edges, gradients, or the sorts of labels that appear in early computational vision’.

two scientists working in two different paradigms and practicing different experiments, using different instruments, and facing different puzzles, have their early visual systems shaped differently enough to make them see the world differently, each one through the lenses of her own paradigm, which has been in essence relativism’s main point all along.

In addition, they may also focus their attention to different locations or configurations and perceive different things (for example, they will disambiguate ambiguous figures differently).

two scientists working in two different paradigms and practicing different experiments, using different instruments, and facing different puzzles, have their early visual systems shaped differently enough to make them see the world differently, each one through the lenses of her own paradigm, which has been in essence relativism’s main point all along.

In addition, they may also focus their attention to different locations or configurations and perceive different things (for example, they will disambiguate ambiguous figures differently).

Surely one can control for attention; one could ask one scientist to focus on a certain location even if she does not expect to see anything important there. Then she will see in the phenomenal sense (her early vision will retrieve) what the other scientist sees in the phenomenal sense, the latter driven by her own theoretical commitments that dictate that she should focus on that location, their theoretical differences notwithstanding. The two scientists may conceptualize the scene differently but the NCC is the same.

Surely one can control for attention; one could ask one scientist to focus on a certain location even if she does not expect to see anything important there. Then she will see in the phenomenal sense (her early vision will retrieve) what the other scientist sees in the phenomenal sense, the latter driven by her own theoretical commitments that dictate that she should focus on that location, their theoretical differences notwithstanding. The two scientists may conceptualize the scene differently but the NCC is the same.

Since the role of attention is restricted only to determining focus before the onset of processing and in no other way does it affect processing, the phenomenal content of early vision (the NCC) is the same as the phenomenal content of late vision, except that in the latter parts of the content are conceptualized. Thus, the phenomenology of their experiences is the same and only the conceptualization may differ.

Since the role of attention is restricted only to determining focus before the onset of processing and in no other way does it affect processing, the phenomenal content of early vision (the NCC) is the same as the phenomenal content of late vision, except that in the latter parts of the content are conceptualized. Thus, the phenomenology of their experiences is the same and only the conceptualization may differ.

Moreover, even if two scientists, because of differences in their theoretical commitments, and work in different environments have stored different associations, when they switch environments they will form each other’s associations (these associations can form easily, require few experiences, and are formed solely on the basis of the incoming signals independent of any top-down effects). Thus, they will be able to see what the other sees. The reason is that learning through experience is data-driven, which means that the same training produces the same implicit memories, and, thus, the persons that undergo the same training learn to perceive the same patterns despite their differing theoretical commitments.

Moreover, even if two scientists, because of differences in their theoretical commitments, and work in different environments have stored different associations, when they switch environments they will form each other’s associations (these associations can form easily, require few experiences, and are formed solely on the basis of the incoming signals independent of any top-down effects). Thus, they will be able to see what the other sees. The reason is that learning through experience is data-driven, which means that the same training produces the same implicit memories, and, thus, the persons that undergo the same training learn to perceive the same patterns despite their differing theoretical commitments.

Dilworth (2005) argues that two scientists with different theoretical frameworks could train their perceptual apparatus so as to produce an invariant lower-level perceptual content, no matter how theoretically different the higher-level perceptual contexts are. Thus, one may remove theoretical biases among experimenters. Scientists in different paradigms could train their perceptual system so as to produce an invariant, theory-neutral representation of the object perceived.

Dilworth (2005) argues that two scientists with different theoretical frameworks could train their perceptual apparatus so as to produce an invariant lower-level perceptual content, no matter how theoretically different the higher-level perceptual contexts are. Thus, one may remove theoretical biases among experimenters. Scientists in different paradigms could train their perceptual system so as to produce an invariant, theory-neutral representation of the object perceived.

For example, one cannot subtract the theoretical factors that have led one to see a duck when viewing the duck/rabbit ambiguous figure in a way that would lead to perceiving a theory neutral figure, that is, a figure perceived by both persons that live in the duck and rabbit paradigm respectively; there is no theory-neutral image in this case, as one perceives either a duck-like or a rabbit-like figure and there is no in-between.

For example, one cannot subtract the theoretical factors that have led one to see a duck when viewing the duck/rabbit ambiguous figure in a way that would lead to perceiving a theory neutral figure, that is, a figure perceived by both persons that live in the duck and rabbit paradigm respectively; there is no theory-neutral image in this case, as one perceives either a duck-like or a rabbit-like figure and there is no in-between.

I disagree with Dilworth that one’s perceptual system could be trained to perceive a theory-neutral representation. The associations acquired through training rig-up the feed-forward perceptual processing and this precludes the possibility of perceiving an invariant representational content, although one could be trained to store the same associations and, consequently, perceive what the other person does.

I disagree with Dilworth that one’s perceptual system could be trained to perceive a theory-neutral representation. The associations acquired through training rig-up the feed-forward perceptual processing and this precludes the possibility of perceiving an invariant representational content, although one could be trained to store the same associations and, consequently, perceive what the other person does.

Despite its cognitive impenetrability, the perceptual system does not function independently of internal restrictions. Visual processing is constrained by certain principles or operational constraints that modulate information processing.

Such constraints are needed because distal objects are underdetermined by the retinal image and because the percept is underdetrmined by the retinal image. Unless the processing of information is constrained by some “assumptions” about the world, perception is not feasible.

Most computational accounts hold that these operational constraints substantiate some reliable generalities of the natural world and reflect the geometry of our world.

Despite its cognitive impenetrability, the perceptual system does not function independently of internal restrictions. Visual processing is constrained by certain principles or operational constraints that modulate information processing.

Such constraints are needed because distal objects are underdetermined by the retinal image and because the percept is underdetrmined by the retinal image. Unless the processing of information is constrained by some “assumptions” about the world, perception is not feasible.

Most computational accounts hold that these operational constraints substantiate some reliable generalities of the natural world and reflect the geometry of our world.

The operational constraints reflect general physical regularities that govern the behavior of objects and the geometry of the environment. They have been incorporated in the perceptual system trough causal interaction with the environment over the evolution of our (and others) species.

They allow locking onto medium size lumps of matter (Haugeland 1998), by providing the discriminatory capacities necessary for the individuation and tracking of objects (the capacity for perceiving objects as cohesive, bounded, and spatio-temporally continuous entities), in a bottom-up, nonconceptual way (Raftopoulos and Muller 2006).

The operational constraints reflect general physical regularities that govern the behavior of objects and the geometry of the environment. They have been incorporated in the perceptual system trough causal interaction with the environment over the evolution of our (and others) species.

They allow locking onto medium size lumps of matter (Haugeland 1998), by providing the discriminatory capacities necessary for the individuation and tracking of objects (the capacity for perceiving objects as cohesive, bounded, and spatio-temporally continuous entities), in a bottom-up, nonconceptual way (Raftopoulos and Muller 2006).

These constraints are hardwired in perceptual systems in that the physiological mechanisms subserving vision implement these constraints, from cells for edge detection to mechanisms implementing the epipolar constraint.

As such, they are not available to introspection and function outside consciousness.

These constraints are not perceptually salient but one must be “sensitive” to them if one is to perceive the world.

These constraints are hardwired in perceptual systems in that the physiological mechanisms subserving vision implement these constraints, from cells for edge detection to mechanisms implementing the epipolar constraint.

As such, they are not available to introspection and function outside consciousness.

These constraints are not perceptually salient but one must be “sensitive” to them if one is to perceive the world.

The constraints constitute the modus operandi of the perceptual system and not a set of stored rules used by the perceptual system as premises in perceptual inferences.

The constraints are implicit, and are available only for visual processing, whereas explicit “theoretical” constraints are available for a wide range of applications.

Implicit constraints cannot be overridden; one cannot decide to substitute them with another body of constraints, even if one knows that under certain conditions they lead to errors.

The constraints constitute the modus operandi of the perceptual system and not a set of stored rules used by the perceptual system as premises in perceptual inferences.

The constraints are implicit, and are available only for visual processing, whereas explicit “theoretical” constraints are available for a wide range of applications.

Implicit constraints cannot be overridden; one cannot decide to substitute them with another body of constraints, even if one knows that under certain conditions they lead to errors.

Since the operational constraints are hardwired in perceptual systems, they cannot be states of the system. A state is formed through the spreading of activation and its transformation as it passes through the synapses. The hard-wired constraints specify the transformation from one state to another but they are not the result of this processing. They are computational principles that describe automatic transitions between states.

Although the states that are produced by these mathematical transformations have contents, there is no reason to suppose that the principles that specify the mathematical transformation operations are states of the system or contents of states in the system.

Since the operational constraints are hardwired in perceptual systems, they cannot be states of the system. A state is formed through the spreading of activation and its transformation as it passes through the synapses. The hard-wired constraints specify the transformation from one state to another but they are not the result of this processing. They are computational principles that describe automatic transitions between states.

Although the states that are produced by these mathematical transformations have contents, there is no reason to suppose that the principles that specify the mathematical transformation operations are states of the system or contents of states in the system.