PSYCH 2220 Perception Lecture 9
COLOUR Trichromacy cones, three photopigments, long wavelength, medium wavelength, short wavelength, colour matching, 'normal' need three lights, colour blindness Opponency adaptation, colour after-effect, lateral inhibition (at level of retinal ganglion cells)
VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions
VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions
VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions
VISUAL ILLUSIONS A classification system: 1 Adaptation illusions 2 Simulation illusions 3 Incompatible cue illusions 4 Geometric illusions
Müller-Lyer Illusion
BOTTOM UP…. TOP DOWN ….
BOTTOM UP 1 eye movements 2 limited acuity 3 physiological confusion
response level cells in a hypercolumn minding their own business
response level when a bar comes on they give a response…
response level But the cells are wired together with INHIBITORY connections
response level so highly active cells inhibit their neighbours the most
response level which releases the higher-firing cells from inhibition and makes them fire more, bringing out the signal better
response level Now we add some other lines..
response level Which activate the cells tuned to those orientations…
response level Which pulls down the response of the vertically tuned cell
A physiological confusion explanation for the Müller-Lyer
BOTTOM UP 1 eye movements 2 limited acuity 3 physiological confusion TOP DOWN 1 empathy 2 “good figure” 3 perspective
EMMERT’s LAW If retinal image stays the same then perceived size will depend on distance small thing close big thing far
The Thatcher Illusion
Do we need to LEARN to see?
EMPIRICIST (all knowledge comes from experience) NATIVIST (knowledge is ‘a priori’; you are born with it)
1 Animal behaviour 2 Blind people recovering their sight 3 Babies’ visual development 4 Adaptation experiments 5 Controlled rearing experiments EVIDENCE
1 animal behaviour
Molyneux’s question: “could a man born blind distinguish a sphere and a cube by sight alone?” 2 blind people recovering sight
3 child development, Fant’z Experiment
4 adaptation
5 controlled rearing
Blakemore video about development
Animal behavour Blind people recovering their sight Babies’ visual development Adaptation experiments Controlled rearing experiments EVIDENCE ……………………. Nativist … Empiricist & nativist …………. Empiricist & nativist …………… Empiricist ……….. Empiricist