L13: Vision 3 Flashcards
What did Helmholtz (1821-1894) argue?
inadequate info is received from senses and needs to be augmented by unconcious inference.
What did Gregory (1980) argue?
perception is an active process involving internal hypotheses and knowledge
Critiques of the constructivist theory of perception
- Fits well with biology
- Does well at explaining “Top Down”
- Does not specify details where perceptual hypotheses are generated
- Under emphasises “Bottom Up”
What did Gestalt propose?
law of pragnanz: perception will conform to the simplest explanation of a geometric configuration.
5 factors of Gestalt’s theory
proximity, similiarity, good continuation, closure and common fate
Critiques of Gestalt’s theory
- principles have proved influential
- combines influence of bottom up with top down perception
- does not explain how grouping happens
What are the 3 models of David Marr’s computational theory of vision?
primal sketch, 2 1/2 D model, 3D model
What is the primal sketch?
groups edges together into elements
What does the 2 1/2 D model do?
add depth
What does the 3D model do?
construct a 3D (viewer invariant) object representation
What does Biedermans recognition by component theory suggest?
geons are combined and matched together
What is a saliemce map?
computational model developed by Itti and Koch
What is the aim of salience maps?
determines which part of the image will attract attention
Critiques of computational models
- sound basis in neurophysiological evidence
- supported by empirical evidence
- successful practical applications
- lacks explanation of top down factors
What did James Gibson study?
Problems experienced by pilots taking off and landing in WWII
What did Gibson propose?
- How info was directly extracted form environment
to guide action - visual system responds to object action affordances
which cues actions
What did Gibson realise that optic array contained?
- focus of expansion = heading
- texture gradient gives cues to depth and size
Critiques of Gibson’s ecological theory of perception
- consistent with contemporary neuroscientific
evidence - envrionmental invariants are important in
computationla models - denial of need for internal representation
- object affordances has important and
underappreciated implications
What is the top-down approach?
Based upon your observations and prior knowledge and is theory-driven.
What is the bottom-up approach?
Based upon the feedback perceived from the world and is data-driven.
