Lecture 4Lecture 4

•• Implicit Implicit vsvs. explicit awareness. explicit awareness

•• The dual visual pathways The dual visual pathways

•• ““HowHow”” vs vs. . ““whatwhat””

•• Optic ataxia Optic ataxia

•• Impaired Impaired ““howhow”” representations representations

•• The visual The visual agnosias agnosias

•• Impaired Impaired ““whatwhat”” representations representations

Visual RepresentationVisual Representation

Explicit awarenessExplicit awareness concerns concernsrepresentations that you are representations that you are

consciously aware of.consciously aware of.

Implicit Implicit vsvs. Explicit Awareness. Explicit Awareness

Implicit awarenessImplicit awareness concerns concernsrepresentations that you are representations that you are notnot consciously aware of. consciously aware of.

Implicit Implicit vsvs. Explicit Awareness. Explicit Awareness

The Titchner Illusion

The Aglioti Experiment

Implicit Implicit vsvs. Explicit Awareness. Explicit Awareness

Task: visually match size vs. grab

Implicit Implicit vsvs. Explicit Awareness. Explicit Awareness

Results: bigger illusion for matching vs. grabbing

Plotted is a difference score,based on subtracting measuredsize of central circle withsmaller surrounding circlesfrom measured size of centralcircle with larger surroundingcircles. As such, the greaterthis value deviates from 1.0, thegreater the size of the illusion.

ThalamusThalamus

VisualVisualcortexcortex

EyeEye

Dual Visual PathwaysDual Visual Pathways

From Psych 100From Psych 100

ThalamusThalamus

VisualVisualcortexcortex

EyeEye

In cortex, visual processing splits into two distinct pathways,In cortex, visual processing splits into two distinct pathways,each dealing with a distinct kind of representationeach dealing with a distinct kind of representation

““WhatWhat””PathwayPathway

““HowHow””PathwayPathway

Dual Visual PathwaysDual Visual Pathways

A problem with A problem with ““visually-guidedvisually-guided”” behavior stemming behavior stemmingfrom impaired representations in the from impaired representations in the ““howhow”” pathway pathway

Optic AtaxiaOptic Ataxia

http://www.metro.co.uk/weird/808516-face-of-jesus-appears-

in-naan-bread

The VisualThe Visual Agnosias Agnosias

Seeing Religious Images in Random Objects

http://www.newsvine.com/_news/2009/11/27/3554482-mass-woman-sees-image-of-

jesus-on-her-iron

http://www.goldenpalaceevents.com/auctions/grilledmary0

1.php

Seeing significance in otherwise Seeing significance in otherwise ““randomrandom”” objects/stimuli objects/stimuli

The VisualThe Visual Agnosias Agnosias

Pareidolia

Form/shapeForm/shape

ObjectsObjects

FacesFaces

XX XX

ProsopagnosiaProsopagnosia

XX XXAssociative Associative agnosiaagnosia

ApperceptiveApperceptiveagnosiaagnosia

XX XX

The Visual The Visual AgnosiasAgnosias

Different areas in the Different areas in the ““whatwhat”” pathway pathwayrepresent different aspects of visual objectsrepresent different aspects of visual objects

From Goodale et al. (1991)From Goodale et al. (1991)

Task:Task:Orient card Orient card

to slotto slot

Result:Result:

An An Apperceptive AgnosicApperceptive Agnosic

From Goodale et al. (1991)From Goodale et al. (1991)

Task:Task:Show widthShow width

of tileof tile

Result:Result:

An An Apperceptive AgnosicApperceptive Agnosic

From Goodale et al. (1991)From Goodale et al. (1991)

Task:Task:Put card inPut card in

slotslot

Result:Result:

An An Apperceptive AgnosicApperceptive Agnosic

From Goodale et al. (1991)From Goodale et al. (1991)

Task:Task:Pick upPick up

tiletile

Result:Result:

An An Apperceptive AgnosicApperceptive Agnosic

An AssociativeAn Associative Agnosic Agnosic

What heWhat he’’s looking at ands looking at andtrying to identify:trying to identify:

An AssociativeAn Associative Agnosic Agnosic

What heWhat he’’s looking at ands looking at andtrying to identify:trying to identify:

An AssociativeAn Associative Agnosic Agnosic

How does he recognize actual objects, and How does he recognize actual objects, and what does this tell us about object recognition?what does this tell us about object recognition?

A test:A test: