minimal sense of self, temporality and the brain

8/22/2019 Minimal Sense of Self, Temporality and the Brain

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Minimal Sense of Self, Temporality and the Brain1

Abstract

Cognitive neuroscientists are currently busy searching for the neural

signatures of conscious experience. I shall argue that the notion of neural

correlates of consciousness employed in much of this work is subject to two

very different interpretations depending on how one understands the relation

between the concepts of state consciousness and creature consciousness.

Localist theories treat the neural correlates of creature consciousness as a

kind of background condition that must be in place in order for the brain to

realize particular conscious experiences. Holists on the other hand take the

neural correlates of creature consciousness to be a part of the core realizer of

a particular conscious experience. My aim in this paper will be threefold.

First I argue we should understand creature consciousness as a property of

those creatures that have a minimal sense of self. Given this conception of

creature consciousness I argue that the localist position is untenable:

Creature consciousness cannot simply be a background condition. Finally I

argue that the minimal sense of self is a consequence of the temporal structure

of consciousness. It follows that any theory of NCCs must explain how

experiences with a complex temporal structure can be implemented in neuralprocessing.

Julian Kiverstein2

University of Edinburgh

Cognitive neuroscientists have amassed a deep and detailed understanding of how

our brains process information from the external world, but the question of how this

information is transformed into conscious experience remains an unsolved problem. The

1Work on this paper was funded by the AHRC under the ESF Eurocores Consciousness in the Natural

and Cultural Context scheme for the CONTACT (Consciousness in Interaction) Project,

AH/E511139/1. Many thanks to Valtteri Arstila, Nini Praetorius and Valdas Noreika my colleagues

on the Volkswagen Stiftung sponsored Subjective Time project for feedback on an earlier draft of this

paper. I would also like to thank the organizers of the CNCC Essay Prize, the anonymous reviewers

for their helpful feedback, the members of the jury, and Mike Wheeler for the many excellent questions

he raised in his commentary. Final thanks go to Andy Clark, Shaun Gallagher, Axel Seeman and to

members of the audience at the Edinburgh prize giving conference.2

University of Edinburgh, Department of Philosophy, Dugald Stewart Building, 3 Charles Street,

Edinburgh, EH8 9AD Scotland.

Website: www.philosophy.ed.ac.uk/contactE-mail:[email protected]


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neurobiologists Francis Crick and Christof Koch (2003) have proposed that the latter

problem is one that is best approached incrementally. They suggest that first

neuroscientists must identify correlations between neural processes and particular typesof experience. Once the correlates of particular experiences have been identified

neurobiologists can then look for common structures that may help them to understand

the mechanisms that underpin consciousness more generally. The idea of neuralcorrelates of consciousness (henceforth NCCs) is central to this research strategy, but

how are we to understand this notion?

I will argue (in 1) that we get very different answers to this question depending

on how we think about the relation between states of consciousness and conscious

creatures.3 According to one perspective, which I will label localism,NCCs are

correlates of particular states of consciousness. Localists take the problem of explainingstate and creature consciousness to be separate and independent problems. On an

alternative understanding of NCCs, which I will label holism, state and creatureconsciousness are conceived of in a way that precludes the possibility of investigating

their neural basis separately. Holists deny that it is possible to identify the neuralcorrelates of particular states of consciousness without also finding the neural

mechanisms that form the basis for creature consciousness. On this conception conscious

experience is best understood as the perspective of a whole creature on its environment.

In 1 I introduce the dispute between localism and holism in more detail. 2

takes on the task of clarifying the notions of state and creature consciousness. I spendsome time attempting to clarify the notion of creature consciousness and introduce one of

the central claims of this paper that creature consciousness is best identified with what Icall a minimal sense of self. In 3 I argue that once we have this understanding of

creature consciousness it becomes difficult to see how creature consciousness could have

a neural basis that did not also form a part of the core neural basis of particular conscious

states. I argue that once we identify creature consciousness with the minimal sense of

self, localism about NCCs must collapse into holism. In 4 I explain how conscious

states can include a minimal sense of self because consciousness has a temporal structure.

I finish up by considering two models of information processing, the first of which

promise to explain the temporal structure of experience, while the second claims toexplain the minimal sense of self. I conclude that neither is entirely satisfactory.

1. Neural Correlates of (Creature and State)

Consciousness

David Rosenthal (1990/1997 & 1993/2005) has argued that a theory of

consciousness must distinguish the question of what it is for a creature to be conscious

from the question of what it is for a state to be conscious. He suggests that knowing what

it is for a creature to be conscious wont help us much with the difficult questions state

consciousness raises:

3The distinction between state and creature consciousness was first made, to my knowledge, by

David Rosenthal, see for instance: Rosenthal (1990/1997) and (1993/2005). Bayne (2007) and Hohwy

(in progress) discuss the relation between creature and state consciousness arriving at positions, whichoverlap in interesting ways with my own. I will unfortunately not have the space to discuss this

overlap in what follows.


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It is the notion of a mental states being conscious that occasions such difficulty

in understanding what consciousness amounts tono special problems impede our

understanding of what it is for a creature to be a conscious creature. A creatures being

conscious means that it is awake and mentally responsive. Being awake is presumably an

unproblematic biological notion. (Rosenthal, 1993/2005, p. 46)

Is Rosenthal right to claim that a biological explanation of creature consciousnesswont help us to understand the nature of state consciousness? Rosenthal tacitly assumes

the correctness of the perspective on NCCs I labeled localism in my introduction.

Localists attempt to pinpoint or localize the neural activity that is correlated with specific

types of experience.4 In doing so they assign explanatory priority to state consciousness

over creature consciousness. The assumption that state consciousness can be investigatedindependently of creature consciousness is rejected bytheories that I will label holist.

Holists do not assign explanatory priority to state consciousness or to creatureconsciousness. Instead they claim we cannot explain state consciousness without also

explaining creature consciousness. Thus they would reject Rosenthals claim that an

explanation of creature consciousness wont help us to understand state consciousness.

We can sharpen the disagreement between holists and localists by taking a closer look at

the notion of neural correlates of consciousness.

Ned Block (2005, p. 46) defines a neural correlate ofphenomenalconsciousness

as the minimal neural basis of the phenomenal content of an experience. While in

Block (2007) he talks of the core neural basis of experience. David Chalmers offers a

similar definition:

A NCC (for content) is a minimal neural representational system N such that

representation of content in N is sufficient, under conditions C, for a representation of

that content in consciousness. (Chalmers, 2000, p. 31)

To say that a neural representational system N issufficientfor the occurrence ofan experience E is to say that nothing else is required in order for an experience of this

type to occur other than activity in the population of neurons of which N is composed.

Block and Chalmers are both careful to say that it is only under certain conditions that

activation of a neural representational system will suffice for a given experience. Both

follow Shoemaker (1981) in making a distinction between a core realizer and a total

realizer. Block defines a core realizeras the part of a neural representational system that

distinguishes one conscious content from another (2007, p. 482). Thus consider a visual

experience as of motion. MT/V5 is a strong candidate for the core realizer for such an

experience because activity in this functionally specialized area is correlated with visual

experience as of motion. Moreover damage to this region causes akinetopsia or motion-blindness. However activity in MT/V5 is widely agreed not to be sufficient for seeing

4Localization of this kind need not be read as the view that there are physically discrete areas of the

brain that encode particular contents, in a fashion akin to so-called grandmother cells. A localist

theory could accept that experience is correlated with large-scale distributed neural activity spread

across geographically disparate areas of the brain. Tononi (2007) has suggested for instance that the

kind of neural architecture required for conscious experience combines functional specialization with

functional integration. He finds such a combination of specialization and integration in the mammalian

thalamo-cortical system, with different parts of the cerebral cortex being specialized for different

functions but with a vast network of connections allowing these parts to enter into dense interactions.

In a similar spirit, Rees & Frith (2007) suggest that it may be interaction between frontal, parietal andstimulus-specific representations in sensory cortices that is necessary for conscious experience of a

particular type.


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motion: In addition recurrent feedback between MT/V5 and V1 may also be required

(Block, 2005, p. 46; Pascual-Leone & Walsh, 2001).

The cells that make up a core realizer could not realize a conscious experience

apart from wider activity in the brain in this sense they are insufficient. To suppose

they could is to suppose we could cut cells from a brain and place them in a bottle andthey would continue to support a conscious experience (c.f. Block, 2007, p. 482),

something that is clearly not possible. The total realizer for a given experience will thus

include the cells that make up a core realizer plus the background conditions required for

these cells to play the role of realizing an experience. Those cells that do not form part of

the core realizer will constitute the background conditions that must be in place if the

core realizer is to do the work of supporting a given type of experience. Block (2007, p.

482) makes a further distinction between causally necessary background conditions suchas cerebral blood flow, and what he calls constitutivebackground conditions. He gives,

as an example of the latter, the activation of the upper brainstem. The upper brainstemdoes not form a part of a core realizer for a given experience because it doesnt play a

role in explaining the contents of consciousness, but it may nevertheless make aconstitutive contribution to realizing experience, as has been argued by Merker (2007)

and Parvizi & Damasio (2001).

Now that we have a firmer grip on the notion of NCCs let us return to the dispute

I began describing above between localists and holists. Localists take the part of a neural

representational system that is the core-realizer to be the NCC. The core realizer is theminimal sufficient condition for an experience of a particular type, but only in the context

of the right background conditions. Amongst these background conditions will be neuralactivity that is correlated with creature-consciousness. The neural correlates of creature

consciousness are assigned the status of either causal or constitutive background

conditions. Holists, on the other hand, deny that the neural basis of creature

consciousness is just a background condition. They argue that neural activity correlated

with creature consciousness should also be treated as making a constitutive contribution

to realizing an experience. Thus, holists challenge the localist conception of the

distinction between the core and the background conditions for a given experience.

In section 3 I will take a closer look at localist theories of NCCs. Before I do so

however I must offer some further clarification of how I will understand state andcreature consciousness.

2. Conscious States, Conscious Creatures, and MinimalSelves

The notion of state consciousness is, I take it, self-explanatory: State

consciousness is a property that distinguishes conscious from non-conscious states.

Subliminal perception (as has been found in masked priming experiments) would be an

example of a type of state that lacks this property, while pains, itches and tickles, sense

experience, and inner speech, are all uncontroversial examples of states possessing this

property. Conscious states can however only occur in conscious creatures.5 So what is

creature consciousness?

5The converse is, I take it, also true: a creature can only be conscious by being in a conscious state.


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Creature consciousness is normally identified with wakefulness and alertness (see

for example, the quote from Rosenthal above). However Bayne (2007, p.18) notes in

passing that this cannot be quite right. Patients in a vegetative state are awake in thesense that their eyes open as part of the normal sleep-wake cycle, but they are not

creature-conscious. They undergo states of unconscious wakefulness (Merker, 2007, p.

112). The same is true of patients in the midst of an absent epileptic seizure: They areunconscious this is why they can be described as absent during the seizure but they

are nevertheless awake. Epileptics can be in the midst of a conversation when a seizure

strikes, stopping them in their tracks sometimes in mid-sentence. Once the seizure is

over patients will often continue where they left off with no recollection as to what had

just happened (Damasio, 1999, pp. 95-101). Conversely, subjects can be asleep but

consciously dreaming. These subjects are surely enjoying something in the way of

creature consciousness, despite not being awake. The traditional understanding ofcreature consciousness is clearly unsatisfactory, but with what should it be replaced?

I have said that there can be no conscious states in the absence of creature

consciousness so perhaps we can make progress on this question by asking what isrequired in order for a creature to have conscious states? Thomas Nagel famously

returned the following answer to this question: Fundamentally an organism has

conscious states if and only if there is something it is like to be that organism

something it is likeforthe organism (1974/1979, p. 166). At least part of what Nagel

seems to be getting at here was the idea that a conscious organism is one that has its own

subjective perspective orfirst-person point of view on the world. I suggest that it is thisnotion of a subjective perspective or first-person point of view that must be clarified if we

are to understand what it means to talk of creature consciousness. We must determinewhen a creature has and when it lacks its own subjective perspective on the world.

Part of what we mean when we talk about a creatures subjective perspective

concerns the distinctive kind ofepistemic access this creature has to its own conscious

states of mind, a kind of access that other creatures lack. The objects of my experience

appear to me in a unique way, even when you and I both undergo experiences of one and

the same object. Suppose you and I are both surreptitiously glancing at the last slice of

cake on a plate wondering which of us will make the first move on it. We are both seeingthe same slice of cake, and we are both aware of the cake in the same type of way (i.e. we

are both seeing the cake). Yet I have a kind of access to my own visual experience thatyou lack and vice versa, insofar as I am conscious of my visual experience but not in the

same way of yours. The kind of access I have to my visual experience but not to yours is

such that I can make my experience the object of a first-person thought. I can think aboutwhat it is like to have this very experience. Your experience is not available to me for me

to think about it in this particular way, though of course I can think about your

experience. We can call this kind of grip a subject has on his own conscious states, which

other subjects necessarily lack,first-person access. When does a creature have first-

person access to its conscious states?

I will follow phenomenological philosophers in claiming that a creature has first-

person access to its mental states only if those mental states include as an intrinsic

property a basic form of self-consciousness. We can label this basis form of self-

consciousnesspre-reflective self-consciousness (see Gallagher & Zahavi, 2008, ch. 3;

Zahavi, 2005). Pre-reflective self-consciousness is to be distinguished from reflectivemodes of self-consciousness in which a subject deliberately takes a step-back and adopts


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the perspective of an observer on her own mind. A reflectively self-conscious subject

might think, for instance, I am angry or I desire some coffee. She is in a position to

think a thought of this kind only because her anger or desire for coffee was already insome sense available to her for inspection prior to any act of reflection. A conscious state

is available to reflect on only if the subject already has some sense that she is herself

undergoing or living through this state. The sense the subject has of herself is aconsequence of the way she is affectedby the state she is undergoing. It is because the

subject is aware of herself as being affected in some way that the state is available to her

to be noticed in a subsequent act of reflection.

Pre-reflective self-consciousness has two (closely related) dimensions to it. The

first aspect relates to what the subject experiences when she undergoes a conscious

experience. The subject doesnt just experience what her conscious state represents asmany representationalists claim (for the classic statement see Harman 1990). In addition

the subject has some experience of the conscious state she is undergoing. As Zahavi(2005) puts it: We are never conscious of an objectsimpliciter, but always of the object

as appearing in a certain way: as judged, seen, described, feared, remembered, smelled,anticipated, tasted and so on (p.121). If I am always conscious of an object as appearing

to me in a certain way, my experience cannot be exhausted by what it represents. It must

also include the way the object isgiven to me. I shall henceforth refer to this dimension

of consciousness as a conscious states mode of givenness since it concerns an objects

appearing or being given in a certain way to a subject.

One and the same object can be given under different modes: It can be seen,

remembered, imagined, and so forth. However there is something these different modesshare in common: A conscious states mode of givenness is always in thefirst-person.

The conscious states that are given to me are necessarily given as mine. The

consciousness the subject has of herself is pre-conceptual and pre-linguistic. It doesnt

require the subject to think of herself as herself, a kind of thought that would require a

first-person concept. All that is required is that the subject have some immediate, non-

inferential awareness of the state she is affected by as her own. Putting these two aspects

of pre-reflective self-consciousness together we can say that for a state to be pre-

reflectively self-conscious it must have a first-person mode of givenness (henceforthfirst-person givenness).

I am going to follow Zahavi (2005) in conceiving of states that are given to a

subject with this quality of mineness as states that include a minimal sense of self. It

might be objected that we simply dont find anything like this minimal sense of self inour ordinary experience.6 Our objector might concede that obviously in order to self-

attribute a mental state, the mental state in question must be conscious, but deny that for

all of his conscious states he has a sense of himself as being in some way affected by

these states. Now consider the thought that I am raising my arm. When I think I am

raising my arm based on a feeling of my arm rising, there is something it doesnt seempossible for me to be mistaken about: I cannot be mistaken that it is me feeling my arm

rise. I cannot be mistaken about this, because when I undergo a proprioceptive

experience, this experience has first-person givenness. Part of what I experience as I raise

my arm is that I am undergoing this proprioceptive experience. The first-person

givenness of this experience renders any act of identification unnecessary, and in the

6My thanks go to Valtteri Arstila for pressing this objection.


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absence of identification there can be no possibility of misidentification. The fact that

first-person thoughts are immune to errors of misidentification (Shoemaker 1968) shows

us that prior to reflection my conscious states are always already given as mine. It isbecause my conscious states are always given to me in this way that I cannot be mistaken

about whether I am undergoing them.

I propose that we identify creature consciousness with pre-reflective self-

consciousness. A creature is conscious when it can undergo states of mind that have

first-person givenness and therefore include a minimal sense of self.

3. The localist account of NCCs

Localist theories identify the neural correlates of the contents of specific

experiences. They study how brain activity changes with specific changes in the contentsof consciousness while keeping factors such as a creatures overall level of consciousness

and sensory input as constant as possible. When a new image strikes the retina it isprocessed rapidly through successive layers of visual cortex. Each layer takes only 10 ms

of processing so that in about 100-150 ms the whole brain can be appraised of the new

information before our eyes. One question that localists ask is therefore at what stage in

this hierarchical processing does consciousness arise? Often localists will also be looking

for what Zeki & Bartels (1999) have described as essential nodes: functionally

specialized brain areas that are necessary for the experience of a particular sensory

feature. We saw earlier (in 1) how V5/MT, for instance, is most likely necessary for the

experience of motion. Damage to or removal of a region that includes V5/MT will rendera subject unable to perceive motion, a condition known as akinetopsia (see Zihl et al.,

1983). In a similar fashion, V4 seems to be necessary for color experience. Damage to

V4 results in achromotopsia or loss of color perception. Localists also predict thatmicrostimulation of an essential node will suffice to bring about an experience of a

sensory feature (or at least it will do so in a creature that is conscious). Thus Tononi &

Koch (2008, p. 247) write: If the NCC could be induced artificially, for instance by

cortical microstimulation in a prosthetic device or during neurosurgery, the subject will

experience the associated percept. They ought really to have added so long as the

subject is not anaesthetized.

Localists use a number of different methods to study the changes in contents of

consciousness. Consider binocular rivalry as an example of one such method. Binocular

rivalry is an excellent tool for localists since it provides a way of studying changes in the

content of visual experience while the sensory input that is being processed is keptconstant. The resulting changes in brain activity do not reflect changes in sensory input

but may instead be taken to reflect differences in brain activity corresponding with the

difference between conscious and non-conscious processing of a stimulus. In a much-

discussed study, Tong and colleagues (1998) presented subjects with a picture of a face to

one eye and a picture of a house to the other eye. Subjects reported that their conscious

experience shifted every few seconds between a visual experience of the face image and

an experience of the house image. fMRI was used to record activity in the fusiform face

area (FFA) and the parahippocampal place area (PPA). FFA responds twice as strongly

to faces as to other stimuli, while PPA responds strongly to place-related stimuli. Astrong correlation of activity in FFA was found when subjects reported their percept

flipping to an experience of a face-image, while strong correlation with activity in PPAwas found when subjects reported experiencing a house image. Moreover, a decrease in


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activity was observed in the respective areas when the preferred stimulus for that area

popped out of awareness. Response fluctuations in PPA and FFA were significantly

larger than those observed in early visual cortex such as V1. Rees & Frith (2007, p. 556)take this to suggest that processing taking place in early visual cortex represents both the

seen and suppressed images. It is only in later processing, as the signal progress further

down the ventral visual pathway, that the competition between the images is resolved andone image dominates while the other is suppressed. Rees & Frith go on to conclude:

distributed object representations in the ventral visual pathway compete for

perceptual dominance, perhaps biased by top-down signals from frontal and parietal

cortex. Successful stabilization of a unitary conscious percept is associated both with an

activated representation in ventral visual cortex of the perceptual content, plus activity in

frontal and parietal cortex. (Rees & Frith, 2007, p. 556)

How do localists conceive of creature consciousness? They conceive of the

neural basis of creature consciousness as having the status of either a causal or a

constitutive background condition: a condition that must be in place if the core NCC is to

do the work of realizing an experience with a specific content. Let us consider first

whether the neural correlates of creature consciousness could have the status of causal

background conditions. Are the neural correlates of creature consciousness, like cerebral

blood flow, necessary for the brain to realize conscious experience without being a part

of the neural basis of consciousness?

Cerebral blood flow must be carefully regulated to meet the brains metabolic

demands. If too much blood is supplied to the brain at a given time this can result in an

increase in intracranial pressure causing damage to brain tissue. Too little blood flow to

the brain and the result can be the death of brain cells and a stroke. Regulation of

cerebral blood flow is therefore necessary for the core neural basis of a given state to dothe work of realizing a particular conscious state. It is not however a part of what it is to

be conscious in the way that say hydrogen is a part of water. Might the neural correlates

of creature consciousness function in a similar sort of way, acting as a condition that must

be in place in order for the brain to realize conscious experience without forming a part of

what it is to be in a conscious state?

This picture of what the NCC for creature consciousness does is incompatible

with the account of creature consciousness I have proposed. I have argued that creature

consciousness consists in the possession of a minimal sense of self. Whenever a statemakes a creature conscious of the world the creature also has consciousness of this state

as his own. The property that makes a creature conscious is, on this view, a part of everyconscious state. It follows that the neural basis of this property must also be a part of the

neural basis of consciousness, and so cannot be a mere causal background condition.

Could the neural correlates of creature consciousness have the status of

constitutive background conditions? A constitutive background condition is a part of the

total neural realizer that is required for a core realizer to do the work of realizing a

particular property. Conceiving of the neural correlates of creature consciousness in this

way we might therefore argue for the following division of labor: The core realizer is thepart of the NCC which explains differences in the contents of consciousness, while the

constitutive background conditions explain something that remains the same across these

variations. The constitutive background conditions might for instance be mechanisms


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that account for the difference between conscious and nonconscious processing of a

stimulus.

Reentrant or recurrent processing is one candidate for a mechanism that might

explain the difference between conscious and nonconscious processing. According to

this theory a stimulus is consciously processed only when a feedforward sweep isaccompanied by a reentrant sweep (Lamme & Roelfsema, 2000). When face sensitive

neurons in FFA are activated, this is necessary, but not sufficient for a visual experience

as of a face. It is only when activity in FFA interacts with higher areas via a reentrant

loop that the face becomes visible. This theory might seem to be challenged by the Super

et al. (2001) finding of recurrent processing in monkeys even when the monkey failed to

report the presence of a texturally defined figure. Lamme (2006), however, asks in

response to this finding: Should we trust the monkeys report? Perhaps reentrantprocessing is sufficient for conscious experience, but conscious experience can occur in

the absence of verbal report (Block 2007; Lamme 2006). Dehaene et al. (2006) rejectthis possibility, arguing that in order for conscious processing of a stimulus to occur,

recurrent loops must spread globally into parieto-frontal regions, which make informationavailable for report. Various masking experiments (e.g. Elliot & Dolan, 1998; Haynes et

al., 2005; Moutoussis & Zeki, 2002; Thompson & Schall, 1999), however, seem to show

that even activation of parieto-frontal regions can be insufficient for conscious

experience.

There is no consensus then on how to explain the difference between consciousand non-conscious processing. The two accounts just canvassed do, however, agree there

is a mechanism that distinguishes conscious from nonconscious processing. Thesuggestion we are currently considering is that this mechanism plays the role of the

constitutive background conditions for a given NCC. Where does this leave creature

consciousness as Ive characterized it? It is of course possible that the neural correlates

of creature consciousness are distinct from the mechanisms that explain the difference

between conscious and nonconscious processing. If this turns out to be the case, we

would have to broaden the class of constitutive background conditions to include the

mechanisms that distinguish conscious from nonconscious processing and whatever

neural activity turns out to be the signature of the minimal sense of self. This wouldinvite the following questions: Why are both kinds of constitutive background conditions

required and how are they related?

A rather neat picture would emerge if the constitutive background conditions that

explain the difference between conscious and nonconscious processing were to alsoexplain creature consciousness. Laureys et al. (1999), for instance, shows that parieto-

frontal regions are impaired in patients that are in a vegetative state. Baars et al. (2003),drawing in part on this data, suggest that activation of parieto-frontal regions may

support the first-person perspective on the visual world (p.671). However we have

noted above that there is evidence challenging the claim that activation of parieto-frontal

regions is sufficient for conscious experience. This data would also present a problem for

any proposal to treat activation of parieto-frontal regions as the correlate of creature

consciousness.

Setting this possibility aside, notice that even if we broaden the constitutive

background conditions to include the neural basis of creature consciousness, this isalready to depart substantially from the spirit if not the letter of localism. Though the


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details differ, most of the proposals sketched above stress the interaction between a core

realizer and the constitutive background conditions. Interaction of this kind would be just

as much required should it turn out that the mechanisms accounting for the differencebetween conscious and non-conscious processing are distinct from the mechanisms

explaining creature consciousness. Once we concede the necessity of this kind of

interaction, however, havent we undermined the very distinction between constitutivebackground conditions and the core neural realizer of a given experience?7 Doesnt the

necessity of this kind of interaction show that the constitutive background conditions are

just as necessary for the occurrence of an experience with a particular content as activity

in the brain areas that constitute the core realizer? Deprived of this distinction, we seem

required to include that the NCC for creature consciousness forms a part of the NCC for

state consciousness.

This leaves the localist facing something of an uncomfortable dilemma. He

cannot treat the neural correlates of creature consciousness as a causal backgroundcondition while accepting the account I have given of creature consciousness.

Furthermore, the distinction between a core realizer of a given experience and a corerealizers constitutive background conditions doesnt hold up. Without this distinction

we are left with a picture in which the neural activity correlated with creature

consciousness is a part of the core neural basis for any given conscious state. Localism

collapses into holism.

4. Temporality and the minimal sense of self

According to holism, the core realizer for a given experiential episode will

comprise neural activity that determines both an experiences content and its first-persongivenness. A holist account of NCCs promises to account for the intrinsic subjectivity ofexperience, a feature of experience many philosophers (and neuroscientists) have

supposed must elude scientific explanation (see e.g. Chalmers, 1996; McGinn, 1991;

Nagel, 1974/1979). The key to explaining this intrinsic subjectivity, according to holists,

is to find the neural signature of the minimal sense of self. In this final section I will

introduce a concept advertised in my title, but which has so far not figured in my

discussion temporality. Temporality, I will argue, may be the bridge connecting neural

processing with the minimal sense of self.

I have argued in 3 that in addition to my being conscious of whatever my

experiences represent, I am always also conscious of myself undergoing theseexperiences. I called this latter variety of consciousness,pre-reflective self-

consciousness. How does pre-reflective self-consciousness come about? This question

is ambiguous: It can most naturally be read as a request for a psychological or

neuroscientific explanation. I will in due course consider two possible explanations

along these lines. I will, however, first outline a phenomenological answer to this

question describing how consciousness must of necessity be structured in order for

conscious states to include pre-reflective self-consciousness. I will assume that this

phenomenological account acts as a constraint on the neuroscientific and psychological

7

Hohwy (in progress) makes a similar point in the course of arguing that to account for consciousnessproper we need to consider the dynamic interaction between the specific (i.e. state) and enabling (i.e.

creature) conditions, given some further background conditions (ms: p.9).


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explanations of conscious experience. Unfortunately, I lack the space to argue for this

assumption (but see Gallagher & Zahavi, 2008, ch.1 & 2 for a defense of this approach).

Our experiences are not temporally punctual presenting us with discrete,

durationless instants in time. What we experience from moment to moment always

occurs within a temporal field, reaching some way back into the past and extendingforward into the future. Consider by way of illustration Sean Kellys (2005) helpful

example of hearing a Soprano singer holding a note. We dont just hear the pitch, timbre,

and loudness of the note; we also hear a sound that is stretched-out through time and that

has continued for a surprisingly long amount of time. We are conscious of our auditory

experience as one that began a short while ago in the past; is continuing in the present;

and that must surely end soon to be replaced by another. The content of this experience

is an event that is extended through time: the event of the Sopranos holding her note.The events mode of givenness also has a temporal character: We are conscious of our

auditory experience as having been going on for some time.

If an experience is to present us with a temporally extended object it must have acontent that is partly a function of what has just past, and of what is about to occur in the

future. Edmund Husserl, in his lectures on time consciousness from 1893-1917

(published as Husserl, 1991), distinguished three parts of a temporally extended

experience, which he called retention,primal impression, and protention. Retention is

the component of an experience that is a function of the recent past. The primal

impression was Husserls name for a phase of consciousness that is constantly arising inthe now. In practice this aspect of an experience is always embedded in a temporal

context of retention and protention, but if as phenomenologists, we abstract away fromthis temporal context, what we are left with is the primal impression. Protention is a part

of an experience that is a function of the near future. In particular, it consists in our

anticipations about what we might experience in the near future. At each instant in time

an experience will be made up of these three components. Retention and protention

contribute a backward and forward-looking temporal context to ongoing experience. It is

the influence of this temporal context on ongoing experience that makes it possible for

the contents of experience to represent temporally extended events.

Retention and protention do more than make it possible for the recent past and

near future to contribute to the contents of ongoing experience. What is retained frommoment to moment is the entire phase of experience that has just elapsed: the retention,

primal impression, and protention of which the previous phase of experience was

composed. Insofar as the entire previous phase of an experience is retained, I will, frommoment to moment, be simultaneously aware both of what my experiences present, but

also of my own ongoing experience. This awareness of ongoing experience is what Ive

calledpre-reflective self-consciousness. The retentional part of an experience thus partly

explains how pre-reflective self-consciousness might come about. It explains how it is

possible for me to be simultaneously aware both of my ongoing experiences and of whatthey represent.

Protention also makes an important contribution to the phenomenology of pre-

reflective self-consciousness. As Gallagher (2005, p. 193) has noted, my anticipations are

implicitly anticipations about what I will experience or what I will do: I dont just

anticipate what is about to happen, but what is about to happen to me. Gallagher arguesthat if someone were to be deprived of this anticipatory sense they would feel like all of


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their conscious states as they unfolded in the future were imposed on them from the

outside. All of their conscious states would have the character of being unbidden: The

person would feel alienated from their own consciousness.

What implications do these phenomenological descriptions have for our

conception of NCCs? I have described how experience must be structured if it is to countas pre-reflectively self-conscious. However in drawing inferences from these descriptions

about the nature of NCCs we must be careful to avoid any content-vehicle conflations.

We must not confuse a claim about the properties of the contents of experience for a

claim about the properties of the brain states, the vehicles of those contents. Dennett

(1991, ch. 6) notes, for instance, that the brain neednt use a temporally ordered sequence

of representations to represent temporal order. It may well be true that a conscious state

must be composed of retentional and protentional components if it is to conclude aminimal sense of self. We shouldnt however expect to find any straightforward

mirroring of this structure at the neural level. Before we can conclude anything aboutNCCs from the phenomenology of experience, we therefore require a framework for

thinking about how temporal structures that exist at the level of content can beimplemented by vehicle properties. I will finish up by briefly describing two (closely

related) information-processing models, which purport to do this explanatory work.

These models describe the general form that neural processing must take to realize

experience with the temporal structure described above. I am unfortunately finishing on

a somewhat critical note. For I will argue that neither account can serve as a basis for a

holist account of NCCs without being further augmented. We will therefore be left withonly a broad idea of the desiderata a holist account of NCCs must satisfy. The task of

describing the holist account in detail must wait for another occasion.

Consider first Rick Grushs (2006) trajectory estimation model (TEM) of sensory

processing. Grush presents the TEM as a model of information processing that aims to

address the question of how Husserls analyses of time consciousness might be neurally

implemented. A holist account of NCCs must explain how temporally structured

conscious states might be implemented in neural processing. Grushs account would

therefore seem like a promising place to look for such an account.

The starting point for the TEM is a hypothesis (which Grush (2004) defends)

that sensorimotor systems must construct internal models of the body and/or theenvironment in order to overcome problems with feedback delays, and to help filter noise

from incoming sensory signals. According to the TEM, sensory systems arent just

concerned with modeling the body or environment as it is right now at a single point intime. Rather our sensory systems construct models for multiple times within a temporal

interval centered on now. This temporal interval includes a past-lag of a fixed duration

land a future-reach of a fixed duration k(Grush, 2006, p. 443-4). A sensory system

that models a whole temporal interval can thereby represent a perceived domain as it was

at multiple times in the past, as it is now and as it will be up to a certain point in time inthe future. As we watch a bowling ball makes its way down a bowling lane, for instance,

our sensory systems model not only where the ball is now but also its having been at a

slightly different location just prior to that and where we anticipate it is heading

(Grush, 2006, p. 444).

Grushs TEM seems to hold the promise of explaining how a subject canexperience in the here and now an event that extends through time. We can have


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experiences that extend through time in this way because our sensory systems construct

models of the environment that have both a trailing edge, lagging a short way back in the

past, and a leading edge that reaches into the future. However Grush is quite explicitabout the limits of his ambitions for his model. His aim is to explain only how

experience can be temporally extended for very short durations of 200 msecs at most. It

doesnt purport to explain temporally extended experience over longer durations (Grush,2006, p. 447). Indeed Grush seems to hold the view that it is only on this time-scale that

we can truly be said to experience an event through time. He suggests that at longer time

scales our brains may group together distinct experiences by subsuming them under

concepts (Grush, 2006, p. 447). However, retention and protention make us aware of our

ongoing experiences over much longer time scales. Grush claims that this is explained

by mechanisms separate and distinct from the TEM. Thus he seems to be committed to

the view that the features of neural processing that explain how we can experience eventsthrough time will not also explain how we are affected by the ongoing flow of our

experiences. If we construe the TEM as a proposal about the neural processing thatunderpins conscious experience, it is most naturally read as a localist theory.8 It purports

to explain how the brain realizes the contents of experience independently of explaininghow the brain realizes the minimal sense of self. I have argued above that localism of

this kind is untenable, and this is no less true of a localist theory that purports to explain

the temporal structure of experience.

Hohwy (2007) presents a model of information processing, which he explicitly

describes as a reductive account of the minimal sense of self (p.1-2). He says thetarget of his explanation is: the pre-reflective feeling that a given movement is

performed by me, or that a perceptual experience is had by mean instantaneous feelingof mineness with which experiences are labeled (Hohwy, 2007, p.1). Hohwy appeals

to what he describes as a predictive coding scheme to account for the minimal sense of

self:

On a predictive coding scheme, the cognitive system implemented in the brain

is hierarchical such that relatively high levels represent hypotheses about probable causes

and issues predictions about future sensory input backwards to lower levels in the system.

If the predictions are good then the incoming signal is attenuated such that only the error

signal is propagated forwards in the system. The error signal is then used, together with

lateral connection, to update the hypothesis so as to generate even better predictions.

(p.7)

As the perceptual systems become better at making predictions about the state of

the environment, so what we sense will acquire a feel of familiarity. When a prediction

is compared with actual incoming sensory signals and a match is found, the incoming

sensory signals will be attenuated. This attenuation will lend the signals a feeling offamiliarity, the subject will have a sense that the experiences she is undergoing are as she

expected. When the causes of ones experience are not what the perceptual systems havepredicted, this feeling of familiarity is replaced by one of bewilderment and alienation

8To be fair, Grush doesnt present his account of sensory processing as a theory of NCCs, but as an

information-processing model that is neutral on the details of implementation. However he does claim

that an account can be given of the contents of temporal experience independently of explaining what

he calls the double intentionality of temporal experience. By double intentionality he means the

feature of temporal experience whereby we are not just conscious of an event extended through time

but also of our ongoing experience.The claim that we can give an account of the vehicles of temporalexperience without also explaining the how the minimal sense of self is physically implemented is just

what the holist denies.


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(p.8). Sensory attenuation is thus the mechanism that Hohwy takes to explain our

awareness of ongoing experience.

We can think of predictive coding as a kind of processing which realizes what

Husserl called protention.9

Hohwy doesnt describe any mechanisms that might explain

the contribution of retention to ongoing experience. Yet it is retention that explains howit is possible to be simultaneously conscious of ones ongoing experience and what ones

experiences represent. Hohwy takes the feeling of familiarity to relate to how a

perceptual content is given [is it predicted or not] (p.8), but we can only have some

sense of how an object is given by means of a retentional component that makes us aware

of our ongoing experience. I dont see how predictive coding could deliver any kind of

awareness of ongoing experience except by working in conjunction with a retentional

mechanism.

Hohwy has given us an important part of the story. It seems very likely that thebrain uses predictive coding to construct generative models concerning the likely causes

of its sensory inputs. This information-processing framework will surely form animportant component in a holist account of NCCs.

10However, just as with Grush, the

story will remain incomplete until we learn how predictive coding functions in

conjunction with a retentional mechanism.

Conclusion

I have argued that the neural basis of state consciousness cannot be identified

separately from the neural basis of creature consciousness. The result is a picture of

experience as the subjective or first-person perspective of a whole animal on its

environment. A creature has its own subjective perspective when it undergoes states thatinclude a minimal sense of self. We have seen that to undergo states of this kind thecreature must undergo states that have a complex temporal structure. I have finished up

by outlining two accounts of neural processing which partially explain how experience

could have such a temporal structure. However I havent yet identified a neural

mechanism that could form the basis for retention. Still we have at least identified a

central question a theory of NCCs must answer if we are to further our understanding of

how neural processing is transformed into conscious experience.

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