av Joerg Bauer 17 år siden
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Mer som dette
So perception depends on the task
Top-Down:
But its 2D
Hyp: it must be a 3D triangle
We know there are no giants
Yet we see one
Most likely one wins
Mask of Hor
Top Down Knowlege
no face, its hollow
Hypo: it must be face
Wrong perception
Strong top down
Necker cube
We constantly build a new perceptual hypo
Kanizsas Triangle
See Triangle although there is none
Strong evidence against direct perception
The Ship
imporverished stimuli are easier recognized one we know what the object is
We can move around
vs. 3D
We can recognize from different angles
Uses Gibson (other modules):
Texture
Stereopsis
Evidence: Motor and Texture processed sepeartly
Gestalt Principles
Termination: Discontinuity
Edge: Change in intensity
Bars (pararllel lines)
Blobs (enclosed arae)
Random fluctionations: Small Changes
Edges: Large changes of intensity
Marr: different module
Algorithms
Only explains simple phenomena
Not fully developed: No "How"
Subtopic
Marr: for fore and background
Rules built in
Where= Gibson
Drives behaviour
What= Gregory
Drives Object recogntion
but grab right size with her fingers
Not recog objects / not know size difference
Once Learned: dorsal
More Motor action
Intital Learning: ventral
More conscious processing
Because of poss. ambiguity we Search world for invariant clues
Depth Clues
occlusion: close cows cover up far cows
Relation to Horizon
Far colours more bluish
Faster moving= closer (motion parallax)
Texture Gradients
Vergance to Motor
Evidence
Work with pilots
pilots undistinguishable with 2D Training material
Training with 2D little impact
Evaluation
Critque
Doesn't explain how it works
Cannot explain phenomena
Visual illusions
Neckar Cube
Kanizsas Triangle
Size constancy
Image on the retina gets bigger but doesnt jump at us
We do make assumptions
Need for realistic / non lab investigations
Strong theory: explains a lot
Affordance
No processing
No memory involved
Objects guide action: make evident what can be done with them
Real World has enough clues
Visual Symstem developed in real world
Ecologist: Most info lost in Laboratory Studies
Bottom up