Synthetic Phenomenology: Exploiting Embodiment to Specify the NonConceptual Content of Visual Experi

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Synthetic PhenomenologyExploiting Embodiment to
Specify the Non-Conceptual Content of Visual
Experience

• Ron Chrisley
• Centre for Research in Cognitive Science
• and Department of Informatics
• University of Sussex
• Brighton, UK
• E-Intentionality Seminar
• October 5th, 2006

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Experience specificationA kind of phenomenology

• Science requires an ability to refer to or
  specify explananda and explanatia
• So consciousness studies needs a way to refer to
  or specify the content of conscious experiences
• Constraints -- Specification must be
• Canonical
• Communicable

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Standard methodThat-clause specification

• "Joel believes that today is Thursday"
• Uses the content to be specified
• Specifications inherit the properties of the
  contents specified
• Constraints on specifications also restrict the
  set of contents that can be specified
• Same for specifications of experience "Mary is
  having a visual experience of a red bike leaning
  against a white fence"

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That-clause specification Problems

• Conceptual, so can't handle
• Fine-grained content (e.g. perception)
• Cognitively impenetrable content (e.g., optical
  illusions)
• Pre-objective content (e.g. animals and infants)
• Transitional content (mediating
  conceptualisations)
• Hot content (with constitutive motivational
  implications for action)
• I.e., can't specify non-conceptual content
• Disembodied no reference is made to the kinds
  of abilities necessary/sufficient for having the
  experience

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Do I have to draw you a picture?

• An obvious way to deal with some of the problems
  is to use non-symbolic specifications
• E.g., for the case of visual experiences, use
  visual images
• Can't just take a picture of the scene the
  subject is seeing (literalism)
• Even in the case of a robot model of experience,
  can't just use the raw video camera output
• For example the current "output" of a human
  retina contains gaps or blindspots that are not
  part of experience.
• Furthermore, our visual experience, as opposed to
  our retinal output, at any given time is stable,
  encompassing more than the current region of
  foveation, and is coloured to the periphery
• So what alternatives are there?

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Method Synthetic Phenomenology

• Use a working robot, and try to specify the
  visual experience it models
• NOT saying that the robot has experience!
• But if there were a sufficiently similar organism
  that does have experience, what would that
  experience be like?
• Not all of experience only lowest level
  (non-conceptual) component of visual experience
• Apply it to the case of an expectation-based
  explanation of various perceptual phenomena, such
  as change blindness

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The Grand Illusion?

• For example, some argue
• Change blindness data show that only foveal
  information has an effect on our perceptual state
• Thus, our perceptual experience is only of the
  foveated world
• Any appearance that anything else is experienced
  is incorrect

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"Actualist" computationalism

• Grand Illusion view is thought to be implied by
  computationalism
• Typically, computationalist (or functionalist)
  theories attempt to map
• A perceptual phenomenal content
• To a computational (functional) state
• By virtue of the latter's actual causal origins
  (and perhaps its actual causal effects)

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Being counterfactual

• But a computationalist theory that places
  explicit emphasis on the role of counterfactual
  states can avoid the Grand Illusion result
• E.g. The phenomenological state corresponding to
  a given computational state includes not just
  current foveal input
• But also the foveal input the computational
  system would expect to have if it were to engage
  in certain kinds of movement
• "Expectation-based architecture" (EBA)

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More on EBA

• These expectations can be realized in, e.g., a
  forward model, such as a feed-forward neural
  network
• The model is updated only in response to foveal
  information
• E.g., it learns "If I were to move my eyes back
  there, I would see that (the current foveal
  content)"

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The EBA explanation

• Thus, change blindness can be explained without
  denying peripheral experience
• Consider the system after an element of the scene
  has changed, but before the system foveates on
  that part of the scene
• The expectations of the forward model for what
  would be seen if one were to, say, foveate on
  that area, have not been updated

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No Grand Illusion

• According to EBA, the (outdated) expectation is a
  part of current experience
• Thus no change is detected or experienced
• So our experience is just what it seems

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Detailed description of the model

• In normal cases of perceived change
• 1) An expectation that if you were to look at L,
  you would see X
• 2) The world at L changes from X to Y
• 3) Your periphery detects change at L A "change
  flag" is put up for L

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Detailed description of the model

• 4 ) Foveal attention is drawn to any region that
  has a change flag up.
• If a few to choose from, one is selected.
• If many to choose from (in the case of a global
  flash, say), change flags are reset and ignored
• 5) Current foveal input at L (Y), Past expected
  input for L (X), and change flag together
  constitute our normal experience of change at L
• 6) The current contents of foveal perception (Y)
  are used to calculate new expectations for L as
  usual

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Detailed description of the model

• "Did you see any change?"
• answered with "yes" only if a change flag
  remained up (there may have been several)
• "What was the change?"
• answered, for a location that was flagged, using
  the past expectation and the actual perception (X
  and Y)

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Modelling change blindness

• Steps 1 and 2, occur, but at the same time as
  step 2, you have a global flash or blink.
• Thus step 3 puts up a change flag for all
  locations.
• Whatever mechanism is used for step 4, attention
  will not, typically be re-directed to L.
• But even if it is, by accident, there will be no
  change flag active to indicate change (step 5).
• The model will be updated as usual (step 6), but
  it will not be experienced as change
• "Change of experience is not necessarily
  experience of change"

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Possible mechanisms for step 4

• all change flags are reset because of the global
  activity
• flag activation for a location only redirects
  attention to the extent that it is different from
  other locations
• flag activity competes in a winner-take-all
  fashion
• one is selected at random

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About the robot and display

• Work being done with Joel Parthemore
• "Filled-in" areas give the content of what the
  robot would expect to see if it moved its head so
  that it is looking in that location
• cf Aleksander's "depictions" depictions of
  depictions
• Black areas do not indicate an expectation to see
  black they indicate to you the absence of any
  expectation for that location
• You can imagine alternate architectures (e.g.,
  generalising neural networks) that have no
  undefined regions of state space
• "Absence of expectation is not an expectation of
  absence"
• Thus, think of the AIBO's head as a big eyeball,
  and its head movements as saccades

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Fertile ground

• Many possibilities here for empirical predictions
  of the human case
• Predicts that if a few changes occur at once, one
  will be aware of several changes, but will only
  be able to give details of what changed for those
  regions to which one could saccade
• Blind spot
• Value is not (yet!) in being a model of human
  vision, but a method and framework for specifying
  experience

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Elaborations to EBA

• Only a simplistic version of EBA presented here
• Can be elaborated to include change not
  instigated by the system itself
• E.g., expectations of what foveal information one
  would receive if the world were to change in a
  particular way

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More elaborations to EBA

• Weighted contributions to experience
• Current foveal info strongest of all
• Expected foveal input after a simple movement a
  little less strong
• Contribution strength of expected results of
  complex movements/sequences inversely
  proportional to their complexity

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Open questions for EBA

• E.g., what is the experience at a non-foveated
  part of the visual field if one has different
  expectations for what one would see depending on
  the motor "route" one takes to foveate there?
• Some "average" of the different expectations?
• Winner take all?
• Necker-like shift between top n winners?
• No experience at that part of field at all, as
  coherence (systematicity, agreement) at a time is
  a requirement for perceptual experience?