The Standard Theory of Conscious Perception

Transcription

1 The Standard Theory of Conscious Perception C. D. Jennings Department of Philosophy Boston University Pacific APA 2012

2 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

3 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

4 The Story of the Trumpet

5 The Dill Story

6 The Lesson of These Two Stories Sound and smell remind us that we sometimes have to work to perceive the world. This work is commonly known to us as attention. In other words, when asked: What allowed you to perceive the sound of the trumpet? or What allowed you to perceive the smell of the dill? I would answer in both cases: Attention.

7 On the Other Hand 1 There is a perceptual background that seems to exist prior to any act of attention. 2 It seems contradictory to say that one needs to attend to something in order to perceive it.

8 Dissolving the Seems Another story: Pay attention! If we broaden the concept of attention to be conscious or subconscious direction by a subject, we get: 1 There is a perceptual background that seems to exist prior to any act of attention but it may be that the perceptual background comes about because of a subconscious direction of attention. 2 It seems contradictory to say that one needs to consciously attend to something in order to consciously perceive it but it may be that we subconsciously attend to something in order to consciously perceive it.

9 The Question And so we are left with a question: Do we need to attend to something in order to perceive it?

10 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

11 Contemporary Theorists on Attention Much of the current work on attention focuses on quantitative selection. That is, these theorists focus on the question of whether we need to attend to something in order to perceive it because of quantitative restrictions. Thus, the debates between these theorists center around the empirical evidence of how much we can perceive versus how much we can attend to. But earlier work has focused on the qualitative selection of attention, which is thought to lead to a transformation of the attended percepts.

12 Earlier Work on Attention: William James Millions of items of the outward order are present to my senses which never properly enter into my experience. Why? Because they have no interest for me. My experience is what I agree to attend to. Only those items which I notice shape my mind without selective interest, experience is an utter chaos. Interest alone gives accent and emphasis, light and shade, background and foreground intelligible perspective, in a word. It varies in every creature, but without it the consciousness of every creature would be a gray chaotic indiscriminateness, impossible for us even to conceive.

13 Earlier Work on Attention: Maurice Merleau-Ponty Attention first of all presupposes a transformation of the mental field, a new way for consciousness to be present to its objects. Take the act of attention whereby I locate a point on my body which is being touched...a vaguely located spot, this contradictory phenomenon reveals a pre-objective space where there is indeed extension, since several points on the body touched together are not confused by the subject, but as yet no univocal position, because no spatial framework persists from one perception to another. The first operation of attention is, then, to create for itself a field, either perceptual or mental, which can be surveyed.

14 My Aim To suggest a theory of conscious perception wherein attention plays a constitutive, rather than a merely causal, role.

15 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

16 Attention the act of prioritizing mental events by a subject the subject is that which we infer from our own experience is having that experience and that which we infer from the behavior of certain organisms is normally governing their behavior. this fits phenomenal experience: attention is felt as an increase in phenomenal priority for a subject. this fits behavioral evidence: attention improves the likelihood of stimulus response, or behavioral priority, by a subject.

17 Conscious Perception the experience of sensory elements bound to a spatio-temporal structure elements signifies the particularities of generalities Burge: a perception a representational perceptual state instance, or the content of a perceptual state instance must always involve the context-dependent singular application of (general) perceptual attributives the spatio-temporal structure may include localized events, patterns, or simply spatio-temporal depth.

18 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

19 From Sensation to Perception What is the difference between sensation and perception? Sensation comes before perception in the causal order and is more deeply tied to the sensory organs and the body. One might have a sensation in one s foot, for example, following a mosquito bite. Whereas one might have a sensation of a mosquito bite, one perceives that it is a mosquito bite. Unlike sensation, perception has sensory content it presents the world as being a certain way to the subject.

20 Being a Certain Way To be certain, something must be distinct from other things. To be a way, something must share qualities with other things. Thus, being a certain way involves both shared attributes between the many items of content and particular instantiations of those attributes held by each item. A stargazer, for example, may perceive stars as each having relative brightness: they share the perceptual quality of brightness, but each of them instantiates a particular degree of brightness.

21 From Within to Across Moreover, integration does not merely happen within an experience, but with constancies that exist outside of the current experience, allowing us to perceive a completely dark room.

22 Twin Problems This is where we happen upon the twin problems of division and unity. Conscious perception has division and unity (both within and across experiences). Sensation does not have division and unity. Moreover, the neural correlates of sensation do not allow for division and unity, since this would minimally require interaction between the neural correlates of individual sensations, which instead are massively parallel. Thus, some mechanism or process is required to bring about the division and unity of conscious perception, both at the neural and the experiential level. These are the problems of division and unity.

23 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

24 The Basic Claim The basic claim of the Standard Theory is that attention provides for the structure of conscious perception by transforming unconscious sensations into potentially conscious percepts. Attention performs this feat by prioritizing (and thus differentiating) the sensations according to a global, subjective standard, through which the sensations-turned-percepts are unified or integrated, thus solving the problems of division and unity.

25 The Basic Argument 1 Some mechanism or process is required to bring about the division and unity of conscious perception, both at the neural and the experiential level. 2 The space-time framework is insufficient because percepts can be distinct without having distinct space-time locations. 3 The subject is a more natural source of division and unity since conscious perception presents itself as inseparable from the subject. 4 To have division and unity at the level of the subject, sensations will have to be divided with respect to a global, subjective standard. 5 The differentiation of sensations according to a global, subjective standard just is attention, or the prioritization of mental events by the subject. 6 Attention is constitutively necessary for bringing about the division and unity of conscious perception.

26 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

27 Beyond Space-Time

28 The Inseparable Subject If this is correct, the space-time framework aids but is not necessary for division and unity. What, then, can play this role of unifying perceptual experience? A clear common factor in all perceptual experience is the experiencing subject. That is, the parts of my perceptual experience are divided and unified for me. When we examine perceptual experience we discover a common pointing back, where the focus of that pointing back is the experiencing subject, me. Another way of putting this is that perceptual experience presents itself as something inseparable from the experiencing subject as internal and private. If we want to explain division and unity we should start with this most common factor of for me -ness, putting aside issues about the space-time framework and the division and unity at other layers, such as color and pitch.

29 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

30 The Basic Argument Again 1 Some mechanism or process is required to bring about the division and unity of conscious perception, both at the neural and the experiential level. 2 The space-time framework is insufficient because percepts can be distinct without having distinct space-time locations. 3 The subject is a more natural source of division and unity since conscious perception presents itself as inseparable from the subject. 4 To have division and unity at the level of the subject, sensations will have to be divided with respect to a global, subjective standard. 5 The differentiation of sensations according to a global, subjective standard just is attention, or the prioritization of mental events by the subject. 6 Attention is constitutively necessary for bringing about the division and unity of conscious perception.

31 The Subjective Standard For the subject to be the source of division and unity, the subject will have to hold some standard against which it differentiates sensations. I call such a standard a subjective standard. A subjective standard can be, for instance, a goal of the subject. Perhaps the subject wishes to find Waldo, in which case the standard might be a visual template of Waldo. In that case, the subject would perceive everything in terms of its relative waldo-ness.

32 The Global, Subjective Standard

33 Outline 1 Introduction Motivation Background 2 Setting up the Problem Working Definitions Division and Unity 3 The Standard Theory An Overview The Role of the Subject The Global, Subjective Standard The Act of Attention

34 How, Now, Attention? Recall that our working definition of attention is the act of prioritizing mental events by a subject. Thus, for the subject to differentiate sensations according to a global, subjective standard is for the subject to prioritize those sensations. That is, the act of attention by the subject results in a field of prioritization according to a subjective standard, where the most-prioritized sensation would be what we normally call the focus of attention and the less-prioritized sensations would be the inhibited surround.

35 The Basic Claim Again The basic claim of the Standard Theory is that attention provides for the structure of conscious perception by transforming unconscious sensations into potentially conscious percepts. Attention performs this feat by prioritizing (and thus differentiating) the sensations according to a global, subjective standard, through which the sensations-turned-percepts are unified or integrated, thus solving the problems of division and unity. OK, but what about those other subjective standards? That is, if attention prioritizes sensations with respect to the global, subjective standard, what does the work of prioritizing sensations for the other subjective standards?

36 Division and Unity at Multiple Levels Returning to an example used at the start of this section, there is a division and unity of green-ness in my visual field. How might this occur? Through non-attentional, pre-subjective prioritization of sensory processing according to goals that reliably fit the global, subjective standard. Groups of neurons may become tuned, for example, to the inputs that normally enable the realization of subjective value and respond preferentially to them.

37 Feature Maps and Anne Treisman Thus, feature maps, or maps of sensory inputs according to pre-subjective standards that regularly contribute to the global, subjective standard, will take place without attention for long-term goals. Thus, one need not find attention necessary for each instance of division and unity, such as the division and unity of individual feature sets, but only for the unity found across perceptual experiences. Importantly, this lines up only part way with Treisman, since she finds (focused) attention necessary for unity at the level of objects, whereas I find (the act of) attention to be necessary for (division and) unity at the level of the subject.

38 The Role of Space-Time To achieve unity across multiple feature maps it will be necessary to have a framework on which to track the values of those maps. That is, the application of a unifying standard to multiple sets of feature values will require a structure through which to compare the values of each set without losing the internal structure of each set. A common spatio-temporal framework is required so that the prioritizations found in the feature maps can be compared with respect to the subjective standard without losing the particular information contained in those feature maps.

39 Theme and Thematic Field Support for the Standard Theory comes from perceptual experience itself: perceptual experience normally has the structure of theme to thematic field, or foreground to background, as was pointed out by Aron Gurwitsch in his Field of Consciousness. It is a strict result of prioritization against the global, subjective standard that a single theme will emerge for the perceiving subject at any given time.

40 Summary Throughout this paper I have illustrated how the structure of conscious perception relies on the act of attention. I have claimed that although the process of division and unity for individual feature-sets can be automatized, unity across features will only be achieved with the real-time application of a global, subjective standard.

41 Outline of Response 1 Points of Clarification 2 Reflections on the Deeper Criticisms

42 Points of Clarification (1 of 2) Felt priority and felt effort are sufficient but not necessary markers of the act of attention, since the metacognitive resources required for determining that these markers are present may not be available in all cases. Nonetheless, I think that the presence of the act of attention can be empirically determined. I favor the dual-task paradigm, although this may have its own problems (e.g. task-switching, split attention).

43 Points of Clarification (2 of 2) I think of attention as only historically necessary for feature binding and ultimately necessary for perceptual constancies, although these seem to be automatic for us at this stage. The Standard Theory does not rely on either point. I should not use the language of figure/ground, as was pointed out early to me by Jesse Prinz, since I do not mean a low-level separation of levels, but a separation of levels of meaning. Theme/thematic field captures my point better.

44 Reflections on the Deeper Criticisms (1 of 2) A Common Spatial Framework: To the extent that mental events are made use of by attention, there will need to be a common spatial framework, in my view. How extensive this framework needs to be I am not sure, but I am attracted by Bill s unified narcissistic framework view. Rich vs. Sparse Experience: Although I am in general agreement with Bill s model of the neural mechanism of attention, I disagree that it entails sparsity on the side of perceptual experience. The Standard Theory does not stand or fall on this point, but I think it is worth noting a) that quantitative limitations may well be highly contextual and b) the level of disparity between the theme and thematic field may well allow for richness in most contexts.

45 Reflections on the Deeper Criticisms (2 of 2) Gist Perception: Gist percepts are sometimes modulated by attention. Dual task studies show that participants can answer questions about a gist stimulus without attention after training, but it is not clear that it is their conscious percept that drives the ability to answer questions. To get the mismatch between conscious perception and attention we need to show that in this very case the percept is conscious. Humans vs. Animals: My arguments turn on the human case, but it may well be that the subject of attention need not be a subject of experience. That is, it may be that the animals Brian mentions have a form of attention that does not aim to divide percepts in experience, but only outside of experience. I may need to revise my historical and ultimate claims after more carefully considering these cases.