of the perceptual system.
4.2 Penetrated Aspects: Architecture and Content
In this section, I will argue that cognitive penetration could be defined with regard to two consequences on the visuo-motor system: its content and its architecture.
Architectural cognitive penetration refers to the changes that higher in-fluences produce on visual neural structures or on peripheral (visuo-)motor mechanisms. The former occur when higher influences modify neural struc-tures of the visual system by re-adapting their functioning, for example, to new environmental conditions. This re-adaptation is the result of neural plasticity in visual cortical and subcortical areas.9 The re-adaptation of visual structures resulting from cognitive modulations makes the visual sys-tem perform operations that the syssys-tem did not carry out before its internal reorganisation. This is the type of cognitive penetration that Churchland (1979, 1988) has in mind, and Fodor (1983, 1988), among others, denies.
Another form of architectural cognitive penetration is observed when
cogni-9Neural plasticity is the ability of the brain to adapt its structural organization to dif-ferent situations arising from developmental, environmental, or traumatic circumstances (e.g.,Crist et al. (2001, 519); Kupers and Ptito (2014); Moore et al.(2011, 812); Chen (2011, 49); Ptito et al.(2012); R¨oder and R¨osler (2004, 722); Schwartz et al. 2002; see also section6.2).
tive influences affect the functioning of peripheral visual mechanisms (mo-tor functions). In such a circumstance, rather than producing structural changes in the visual system, the cognitive system influences the behaviour of these structures. Higher influences determine the location where the eyes will be directed to, a location that would not be picked out without the influence. This involves the type of cognitive penetration discussed by Wu (2013).
Content cognitive penetration refers to the cognitive influences that af-fect the information the visual system processes, rather than its architec-ture. The visual system converts physical stimuli into information useful for the rest of systems by performing a series of transformations on them.
If during the transformation of the inputs into outputs the visual system is cognitively penetrated in such a way that the top-down influence adds, mod-ifies, or substitutes any piece of information external to the visual process, then there is content cognitive penetration. Content cognitive penetration implies changes in the perceptual content processed by the visual system but it does not involve any architectural modification. Content cognitive penetration is the most discussed form of cognitive penetration in recent philosophy (Macpherson 2012, ming; Siegel 2012, 2013c; Siegel and Silins ming; Stokes 2012, 2013).
Concisely, architectural cognitive penetration involves top-down influ-ence that change the internal visual operations that determine how the visual system selects, retrieves, transforms, stores, controls perceptual con-tent. In contrast, content cognitive penetration concerns all these cognitive effects that alter perceptual content.10
Let’s clarify the concepts of architectural and content cognitive penetra-tion. I have said that architectural cognitive penetration refers to changes
10An analogy could help to understand the architectural/content dichotomy. Archi-tectural cognitive penetration designates the modification we could carry out on the hardware (physical structure) and software (programs) of a computer: we can change their physical component (a camera or a memory chip) or update a program. Infor-mational cognitive penetration concerns the information we enter in the computer and which is transformed by these programs: in a text document we can add or erase some text, or substitute the font colours.
in the functioning of the system either by reorganising its internal structure or guiding the behaviour of its external mechanisms. In contrast, content cognitive penetration involves changes in the content of perceptual states.
When cognitive or perceptual states are tokened, there is some physical ac-tivity in the brain. By ‘physical acac-tivity’ I mean the firing of neurons.11 This follows from what Kim (1998, ch. 1; 2000, ch. 1; 2005, ch. 1) calls
“minimal physicalism”, i.e., the claim that mental (and semantic) proper-ties supervene on physical properproper-ties: there is no change in mental states without a correlative physical change. Hence, both architectural and con-tent cognitive penetration involve changes in neural activity. In addition, both architectural and content cognitive penetration might involve neural plasticity at some point. It could be possible that during the cognitive penetrating process (either architectural or content) some visual neurons readjust their synapses by changing their firing thresholds or their shape as a consequence of brain basic biological functions. But these modula-tions need not be the result of either architectural or content cognitive penetration. In other words, the visual system (and the brain in general) is constantly readapting its structure by restoring connections (due to the fact that neurons are constantly dying and being generated), optimizing its capacity, storing new information (memories are stored thanks to physical changes occurred in brain libraries), and the like. (These cases might desig-nate ‘task-irrelevant cognitive influences on perception’ discussed in section 3.2). Although all these plastic changes could occur during cognitive pen-etration, the neural reorganisation resulting from it might be unrelated to the cognitive penetrating process; they occur instead in virtue of ecological brain functioning. Therefore, the architectural/content dichotomy cannot be rejected by invoking the supervenience of the mental on the physical.
Architectural changes produced by cognitive penetration are those cog-nitive modulations that modify internal visual operations responsible for
11That is, the electrochemical exchange between neurons due to the different of voltage across their membranes, and the chemical transmission of sodium, potassium, chloride, and calcium.
selecting, retrieving, storing, controlling perceptual content. Architectural cognitive penetration of peripheral visual subsystems (visuo-motor mech-anisms) are those influences that affect the stimuli that will be selected from the visual scene and processed by the system. Architectural cogni-tive penetration modifies how the visual component of the system (early and late vision) will process perceptual content. This form of influence in-volves brain activation as well as neural reorganisation. Content cognitive penetration designates the influences that the cognitive system has on per-ceptual content. For instance, the output produced by the (modular) early visual system results from the processing of information carried out by the retina, other organs of the system (e.g., the visual cortex), and other infor-mation stored in the system’s database necessary to transform the stimulus (see section 2.2 and the characterisation of informational encapsulation).
If cognitive influences affect the perceptual content due to the stimulus at this early level by adding, subtracting, or substituting any piece of visual information, there is content cognitive penetration.
The architectural/content distinction could be better understood in terms of the concepts of ‘signal’ and ‘channel’ in Dretske’s (1981) theory of information. Dretske (1981, ch. 6) claims that perceptual systems carry information in an analog way and the cognitive system transmits informa-tion in digital form (see secinforma-tion 3.4.1). A signal carries the information that s is F in a analog form if and only if the signal does carry additional information about s, information that isnot nested ins’s beingF (Dretske 1981, 137). Perceptual states are analog because they deliver richer infor-mation than cognitive states (Dretske 1981, 141-142). The signal of a visual system is the sensory information extracted from the physical stimulus (the light reaching the retina) and transformed into an (analog) visual repre-sentation. This signal is transmitted and converted by a channel, that is, the visual system (or any other sense modality) (Dretske 1981, 145-146).
Dretske (1981, 56) claims that the model of human cognition considers “an organism’s sensory systems as channels for the receipt of information about their external environment”.
The signal/channel distinction has a direct correlation with the con-tent/architectural dichotomy. I will consider any change in the signal of the perceptual process as a change in thecontent of perceptual states, and any change in the channel as a modulation in the architecture of the sys-tem. It is worth noticing that visuo-motor mechanisms are not considered by Dretske as part of the channel, they compose the peripheral system that selects the information that will enter the channel (Dretske 1981, 143-150).
According to this interpretation, peripheral mechanisms (e.g., visuo-motor functions) can be regarded as peripheral structures of the channel. There-fore, architectural cognitive penetration designates cognitive influences on the channel’s peripheral (motor) and central (early and late visual) struc-tures.
Because the dichotomy signal/channel is not defined in terms of neural activation or neural plasticity, it is easy to notice that not any physical change represents a modulation in the channel or the content. If cognitive influences producing neural changes do modify the channel (the way the signal is converted) there is architectural cognitive penetration. If cognitive influences directly change the signal (but not how it is converted) there is content cognitive penetration. If top-down modulations impact on the signal or the channel but neither modify the content of the incoming input, nor how the system converts the signal (i.e., the channel), this counts neither as architectural, nor as content cognitive penetration.12
Let me illustrate the architectural/content cognitive penetration distinc-tion. Imagine an automatic espresso coffee machine, the kind of device that makes coffee directly from coffee beans. The machine has a compartment to store coffee beans, a water tank in the back, and an integrated grinder which can be adjusted from a coarse to an extra-fine mill by turning a knob.
Suppose that the standard tuning to obtain a good coffee is a fine ground.
When we press the start-coffee button, the grinder mills the beans to fine
12These latter cognitive modulations were designated in section 3.2as ‘task-irrelevant cognitive influences on perception’: cognitive influences may have the role to help the visual system to repair broken connections or readjust existing ones without producing any architectural or content change.
ground and deposits the coffee powder in the integrated portafilter. Once the milled coffee is in the filter, water circulating inside the heating circuit passes through the filter. Finally, the coffee drops from the spout and fills up the cup.
Before pressing the start button, we can modify the quality of the coffee in two ways: either by changing or adding different products than those normally needed for the machine to make coffee (i.e., water and coffee beans) or changing some settings of the machine mechanism (i.e., turning the knob to adjust the mill of the grinder). Thus, we can add milk to the water tank instead of water; the resulting coffee will be a strong coffee latte. Similarly, we could change the grind of coffee beans from fine to coarse ground and obtain a very light coffee.
We could also alter the machine during the coffee-making process. Imag-ine that we open a lid which gives access to the water tubes and, using a syringe, inject milk into the tube. The coffee obtained will be adulterated:
it will be coffee with milk. Instead, we may tamper with the machine by turning up the grinder knob changing it from fine to coarse mill. The re-sulting coffee will be lighter and more watery, rather than strong and tasty as it should be. These changes are external influences we inflict to the coffee machine during the coffee-making process.
Suppose that the visual system works like this automatic espresso coffee machine. Whereas the inputs of the visual system are physical stimuli, the inputs of the espresso machine are coffee beans and water. Analogously, while the output of the visual system is a perceptual experience, the out-put of the coffee machine is the coffee which drops from the spout and fills up the cup.13 The coffee in the cup at the end of the coffee-making pro-cess represents the content of the perceptual experience. The two previous cases in which we can tamper with the coffee machine illustrate respectively instances of content and architectural cognitive penetration.
13For the sake of simplicity, the visual process taken into consideration here involves both early and late vision, i.e., it goes from the detection of visual stimuli to the produc-tion of perceptual experience.
In the former case, during the coffee-making process we influence the content (represented by water and coffee) processed by the machine by injecting milk into the tubes. The content of the machine will be composed of both the products it normally processes (coffee beans and water) and the external (penetrating) element (milk). The result of the process will produce a milky coffee. Notice that the internal structure of the machine remains unaltered: there are no changes in its architecture; the machine performs the same operations that it usually does.14 This example is analogous to content cognitive penetration in the visual system. There are two sensory stimuli (a packet of coffee beans and a bottle of water) which represent the content the visual system processes which is penetrated by some cognitive content (e.g., a belief about a glass of milk). As a consequence, the content of the cognitively penetrated experience represents, in addition to the packet of coffee and the bottle of water, a glass of milk.
In the latter illustration, the content of the coffee machine is the same throughout the process (coffee beans and water). What this time is exter-nally influenced is the mechanism of the device (the grinder). The external influence inflicted during the coffee-making process alters the structure of the coffee machine: the grinder settings change. This structural modulation subsequently influences the mill of coffee and then the quality of the output (the coffee in the cup). A similar case occurs in architectural cognitive pen-etration: the content of the visual system comes exclusively from the visual input generated by the packet of coffee and the bottle of water. However, due to the modulation of the structure of the system, the transformations exerted on the input are different. Cognitive penetration of the visual ar-chitecture modifies the neural structure responsible for the transformation of the visual input.
It is interesting to remark that the coffee machine example also helps to
14It seems clear that the amount of milk injected in the tubes produced some physical changes: because milk is thicker than water the machine might use more energy in order to process the liquid. But the architecture of the machine does not change: it does what it normally has to do, to wit, to process liquid with a certain density between 1000 and 1050ρ(kg/m3) such as water and milk.
exemplify the early and late vision distinction discussed in section2.1and to illustrate the different transformations the visual system may effectuate on the perceptual content at a subpersonal and personal levels (section 3.4).
Very roughly, the visual process goes from the selection of visual stimuli to the production of a perceptual experience. Early vision is the process which delivers primitive outputs about properties such as colour, shape, texture, and so on. And late vision is the process that, according to some authors, uses attention to grasp some primitive objects which form the objects that our perceptual experiences will represent (e.g., Rensink 2000a, b; Raftopoulos 2009a). Similarly, the coffee-making process goes from the selection of the input (water and coffee beans) to the production of the output (the coffee in the cup). But this process can be split into early and late operations. An early coffee-making process could be identified with the stage in which the coffee grains are milled and the water is heated. Primitive outputs would be both the dry and milled coffee before they are put in the portafilter and the hot water circulating through the tubes of the machine.
A late coffee-making process could be pictured by the processing occurring at the portafilter level. Here milled coffee and water converge together to make coffee. The portafilter might function as the late visual system, and the filter as an attentional mechanism which selects the primitive inputs (milled coffee and hot water) and put them together to produce the coffee in the cup (the coffee machine’s perceptual experience). Some grains of coffee would drop outside the filter, and some water would remain in the tubes and the filter; those are the proto-objects that have not been selected or grasped by the filter and which do not form part of the content of the cup (do not become consciously available). Cognitive penetration of early vision might then be illustrated by turning the knob of the grinder or injecting milk in the tubes. This might respectively count as architectural and content cognitive penetration. Similarly, architectural and content cognitive penetration of late vision could be pictured by some external influences on the structure of the portafilter or the injection of milk in it.
In section 3.4, I explained that the (subpersonal) content processed by
the visual system is different from the (personal) content of the experience.
This also occurs in the present example. The content inputs of the coffee machine (cold water and coffee beans) are different from its content output (hot coffee liquid). The input content is transformed several times: cold water is heated, the beans are milled, these products are mixed together in the portafilter, but they are different from the content of the cup. This distinction illustrates the different between the content of perceptual states and the content of perceptual experience.15
There is a further distinction that needs to be made: cognitive influ-ences on the visual system can be synchronic or diachronic. Synchronic cognitive penetration occurs when the cognitive influences affect the per-ceptual system simultaneously to the perper-ceptual act. The perper-ceptual system is biased by the cognitive system at the same time the sensory stimulus is perceived. Diachronic cognitive penetration takes place when the influence of the subject’s cognitive background on the perceptual system is prior to the perceptual act. The perceptual system has been affected before, and perhaps a long time before, the sensory stimulus is perceived.16
So, two different sub-types of cognitive penetration can be distinguished in architectural and content cognitive penetration. A type of architectural cognitive penetration (which might be both synchronic or diachronic) occurs when intentions influence visuo-motor mechanisms (peripheral subsystems) and guide eye movements to specific locations (Wu 2013).17 Architectural
15The coffee machine example does not pretend to be exhaustive or describe visual functioning; it intends to represent in a more intuitive way what the differences between architectural and content cognitive penetration are, and how other aspects explained in this thesis (namely early and late visual stages) may be illustrated.
16For uses of the synchronic/diachronic dichotomy, see Churchland (1988); Cowan (2014); Fodor (1984, 39-40; 1988); Goldman (1979b, 167); Lyons (2011, 298); Stokes (Stokes 2013, 652;Stokes 2014, 20-21);Swinburne(2001).
17Wu (2013, 660-661) seems to leave open the possibility that the visuo-motor system could be both diachronically or synchronically penetrated. Intentions might constitute a database of plans proprietary of either the (practical reasoning) cognitive system or the visuo-motor system. If intentions are stored in the cognitive system, the penetration of visuo-motor mechanisms is synchronic: intentions are activatedsimultaneously to the perceptual act every time the perceptual circumstances match the conditions in which the intention applies. If intentions are stored in the visual system, the penetration of visuo-motor mechanisms is diachronic: intentions penetrated the visual system for the
cognitive penetration is synchronic when top-down effects occur during the perceptual act. In certain perceptual learning studies, intensive training elicits, simultaneous to the perceptual task, cognitive signals that produce neural reorganization in the visual brain areas involved in the task. The effects occur at the early as well as the late visual level (Cecchi 2014).
Architectural cognitive penetration is diachronic when structural changes occur before the perceptual act. For example, due to the plastic condi-tion of the brain, intensive training during perceptual learning may elicit cognitive influences which later produce neural reorganisation in the visual system (e.g.,Churchland 1979,1988;Cecchi 2014). I scrutinize architectural cognitive penetration in chapter 6.
Architectural cognitive penetration is diachronic when structural changes occur before the perceptual act. For example, due to the plastic condi-tion of the brain, intensive training during perceptual learning may elicit cognitive influences which later produce neural reorganisation in the visual system (e.g.,Churchland 1979,1988;Cecchi 2014). I scrutinize architectural cognitive penetration in chapter 6.