Sensory Substitution and Qualia

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Sensory Substitution and Qualia

• Paul Bach-y-Rita
• Presented by Allen Y. Houng

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Issues

• Can visual experience be produced not through
  visual pathway, but through other sensory
  pathways such as tactile?
• The case of TVSS

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TVSS
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• After sufficient training with the TVSS, subjects
  reported experiencing images in space, instead of
  on the skin.
• Limitations visual clutter, shadows, fast
  movement, emotional messages

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Other Sensory Substitution SystemsAmerican Sign
Language (ASL)Bellugi and Klima (1979)

• Deaf people
• a different language system based on hand
  movements, special localization, and visual
  recognition
• parallel / linear processing
• Left hemisphere of right-handed deaf people is
  also specialized for a sign language task

• Normal people
• language system base on auditory-vocal speech
• linear/sequential processing
• Left hemisphere of right-handed normal people is
  specialized for a language task

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Cutaneous Sensory Substitution Following Leprosy
(Collins and Madey, 1974)

• Leprosy causes the lost of hand sensation in
  patients
• A special glove / transducers in fingertips /
  transmits stimuli to the forehead
• The patients can distinguish rough vs. smooth /
  soft vs. hard / the structure of the surface
  (curve, irregular)

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Philosophical Issues

• Is the TVSS-perception a genuine visual
  perception?

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Morgans two arguments (1977)

• The horseshoe crab can see. There seems to be no
  clear criteria for distinguishing seeing from not
  seeing.
• Behavioral equivalence implies experience
  equivalence (behaviorism?)

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Qualia

• The TVSS-perception has no emotional or affective
  component as normal perception in the case of
  seeing wife/girlfriend or Playboy (Gregory and
  Wallace, 1963)
• Subjects of TVSS (adolescents or adults) often
  report displeasure at the absence of qualia
• Question Will qualia develop with extended use
  of the substitution system?
• Hypothesis when TVSS are used form infancy, the
  qualia will develop.