Autism and visual perception

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Autism and visual perception
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Structure

• Weak Central Coherence Theory
• Global/ Gestalt/ Spatial frequency
• Audition
• Multisensory integration
• Mirror neurons

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Weak Central Coherence Theory

• Frith (1989)
• Frith and Happé (1994)
• Happé (1999)
• Happé and Frith (2006)
• Local/global processing bias
• QJEP (2008 - 61(1))

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Navon (1977)
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CEFT
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Block design task (Shah and Frith, 1993)
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ASD drawing of a house
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Fragmented Figures Test (Snodgrass et al., 1987)
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Impossible figures (Booth, 2006)
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Visual Illusions

• Happé (1996)
• Children with ASD fail to succumb to visual
  illusions
• Ropar and Mitchell (1999) failed to replicate

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Titchner Circles
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Muller-Lyer
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Pogendorf Illusion
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Happé and Booth (2008)

• Reduced global processing
• Increased local processing
• Both
• Need a task that separates out the two

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Gestalt grouping
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Proximity (rows)
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Proximity (columns)
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Similarity
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Closure
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Brosnan and Scott (2004)

• Global vs. Gestalt
• Children with ASD fail to perceive Gestalt
  grouping principles
• Drawing did conform to Gestalt principles
• Dorsal/ ventral streams
• Right/ left hemispheres

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Explicit cuing

• Children with ASD can be cued (Plaisted et al.
  1999).
• Which one looks bigger/ longer
• Which one is bigger/ longer
• (Brosnan and Scott)
• Access to both representations?

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Spatial frequency

• The two sides of perception (Ivry and Robertson,
  2000)
• High Spatial Frequency (Left)
• Low Spatial Frequency (Right)
• Visual field

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Auditory too

• Heaton (2003)
• http//www.isvr.soton.ac.uk/SPCG/Tutorial/Tutorial
  /Tutorial_files/Web-hearing-Shepard.htm

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Echolalia

• Exact repetition of speech
• Imitation in ASD
• Echopraxia (Russell, 1997) involuntary
  imitation of observed actions

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Mirror Neurones

• Mirror neurons code for the same action, whether
  it is perceived or enacted (Gallese et al.,
  1996).
• Williams et al. (2001 2004 2006) suggest that
  the imitative problems in autism may be related
  to abnormal function of mirror neurons.
• Lead to ToM deficits

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STS

• The superior temporal sulcus (STS) is argued to
  have mirror neurone properties
• STS associated with cross-modal binding and
  audiovisual integration in speech perception
  (Calvert, 2001 Calvert et al., 1997 2000).
• STS associated with social brain (Baron-Cohen
  et al., 1999)

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Iarocci and McDonald (2006)

• Multisensory integration is a useful way to study
  the perceptual experience of those with ASD
• Frequently referred to, yet rarely defined.

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McGurk MacDonald (1976)

• McGurk effect
• Say /aga/
• Hear /aba/
• Perceive /ada/

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Williams et al. (2004)

• Decreased McGurk effect in Autism (bimodal)
• Maybe due to decreased speech reading ability
  (unimodal)
• But children with ASD do look at mouths more than
  eyes (Klin et al., 2002 Joseph and Tanaka, 2003).

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Baldi Williams et al., 2004
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McGurk

• Ba (bilabial 1)
• Ga (velar 7)
• Da (Alveolar 4)
• We heard
• Ba (bilabial 1)
• Va (labiodental 2)
• Tha (Dental 3)
• Da (Alveolar 4)

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Brosnan et al.

• Decreased McGurk effect in Autism
• Even when accounting for Unimodal performance

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Increase in visual influence
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• So why do Williams and Brosnan get different
  results?

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Back to mirror neurones

• Automatic imitation effect compatible faster
  than incompatible
• Animacy effect Imitation effect is greater when
  observing a human than anon-human

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Robot hand Bird et al., 2007
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Compatible (RT,ms, grey) Incompatible (RT,
ms,black)
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ASD human Control human ASD robot
Control robot
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Findings

• Both ASD and controls showed an automatic
  imitation effect (larger in ASD)
• Greater compatibility effect because ASD had
  problems inhibiting imitation
• Distinguishing self from others, relies on ToM,
  crucial component of imitation inhibition.
• ASD had an enhanced animacy biased

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So why is a difference in animacy interesting?

• What if ASD have enhanced discrimination between
  animate and non-animate?

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Happé et al. (2006)

• Time to give up on a single explanation for
  autism
• Deficits in all three aspects of triad required
  for diagnosis
• social difficulty, communicative impairment and
  rigid/ repetitive behaviour are only modestly
  related.
• Social vs. non social