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Introduction to
Neuropsychology
Visual Perception
Basic Anatomy
 Retina > Striate cortex (V1/V2)
Visual Perception
The Visual System
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 Striate cortex (V1/V2) > ...
Visual Perception
The Visual System
(Ungerleider & Mishkin, 1982; Carey, 2010)
 Striate cortex (V1/V2) > Parietal (dorsal) and Temporal (ventral)
lobes
Visual Perception
The Visual System
(Ungerleider & Mishkin, 1982; Carey, 2010)
Visual Perception
Vision for Perception
(e.g. Aglioti et al., 1995)
 Ebbinghaus Illusion: size contrast
 Vision for perception: world-based; size/location relative to
other objects; view-point independent; allocentric co-ordinates
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Visual Perception
Vision for Action
(e.g. Aglioti et al., 1995)
 Vision for action: effector-based; size/location estimated in
real-time/online; view-point dependent; egocentric co-ordinates
Visual Perception
Two Visual Systems
(Ungerleider & Mishkin, 1982; Milner & Goodale, 1995; 2008)
Two Visual Systems
Vision for Perception
 Agnosia: prosopagnosia; achromatopsia; object agnosia;
ventral simultanagnosia; visual form agnosia
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Vision for Perception
Visual Form Agnosia (D.F.)
Visual for Perception
Visual Form Agnosia (D.F.)
 Carbon monoxide intoxication at 35yrs
 At 4 months
(Milner et al., 1991)
x No recognition of drawings
x No (single) letter recognition
x No shape, size or orientation
discrimination
x No appreciation of symmetry
x No Gestalt perception (continuity)
x No recognition of faces
(prosopagnosia)
x No recognition of common objects
 Average IQ
 Visual acuity
 Colour vision
 Tactile recognition
 Normal digit span
Visual for Perception
Visual Form Agnosia (D.F.)
(Goodale, Milner, Jakobson & Carey, 1991)
 (a) Visually guided manual size estimates; (b) Visually guided
grasping
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(Goodale, Milner, Jakobson & Carey, 1991)
Visual for Perception
Visual Form Agnosia (D.F.)
(Goodale et al., 1994)
 Visual (form) discrimination at chance (white = same orientation;
blue = different orientation)
Visual for Perception
Visual Form Agnosia (D.F.)
(Goodale, Jakobson & Keillor, 1994)
Visual for Perception
Visual Form Agnosia (D.F.)
 A = object present; B = pantomimed actions to removed objects
(requires visual memory representation)
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Two Visual Systems
Vision for Action
Vision for Action
Optic Ataxia
Vision for Action
Optic Ataxia (R.V.)
(Goodale et al., 1994)
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(Goodale et al., 1994)
Vision for Action
Optic Ataxia (R.V.)
(Milner et al., 2003)
Vision for Action
Optic Ataxia (I.G.)
 A = object present; B = pantomimed actions to removed objects
 Requires visual memory representation
Vision for Action
Optic Ataxia (A.T.)
(Milner et al., 2003)
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Discussion
Functional Anatomy…
(Fogassi & Luppino, 2005; Iacoboni, 2006; Culham & Valyear, 2006)
 Intraparietal Sulcus (IPS)
 aIPS - hand; lIPS – eye; mIPS - arm; vIPS - mouth
Discussion
…Functional Anatomy
(Gill-Spector et al., 2001; James et al., 2003)
 Lateral Occipital Cortex (LOC)
 Left = Recognition of objects; Right = Recognition of line
drawings
Discussion
Double Dissociation?
 Reaching to centrally vs. foveally fixated objects in OA
 Evidence of dorsal-ventral pathway(s)
(Pisella et al., 2006)
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Vision for Perception
Associative Agnosia