Perception Flashcards
perception=
process of interpretation of sensory data
sensation=
physical stimulation of sense organs by molecules or particles
dogma of structuralism=
perception is the build up of individual sensations
dogma of gestalt=
whole is more than the sum of its parts
dogma of direct perception=
sensations are rich and involve no cognition or mediation, rather the sensations themselves give enough information so no top down is needed
dogma of contructivism=
perception is based on expectation
what is the most recent theory of perception and what does it entail?
analysis by synthesis (Neisser) -model of perception that combines bottom up and top down mechanisms
what are the 3 laws of structuralism?
webers law, law of specific nerve energies (muellers law) and absolute threshold of just noticeable difference
webers law=
size of just noticeable difference is proportional to the original stimulus value
law of specific nerve energies=muellers law=
each nerve is excited by one kind of energy, and stimulation of that nerve is seen by the brain as being that kind of energy (ex push eyeball see flashes light)
absolute threshold=
minimum amount of sensory stimulation required to experience something on 50% of occasions
critical evaluation of structuralism:
describing the percept in terms of just physical values doesn’t capture the complexity of perceptual information
what is the overarching law of gestalt?
the law of precision, which is that perception is as good as conditions allow and is constructed according to economy and parsimony
what are the 6 sub laws of gestalt?
common fate, proximity, symmetry, closure, continuity,similarity
what are the 3 considerations of direct perception?
optic flow (change in optic array due to movement), texture gradients (allows depth clues), affordances (abstract properties known without previous experience)
critical evaluation of gestalt:
identifies lots of laws and shows perception is more than the sum of its parts, however it is descriptive rather than explanatory and only describes 2d rather than 3d perception
critical evaluation for direct perception:
gives unambigious info about external world and of the ability to pick up on information without inference, however it doesn’t explain mistaken perceptions and illusions and expectation (ex Ames room)
thesis for constructivism:
perception involves looking beyond immediately given evidences of senses
constructivism gives an account of monocular and binocular vision:
perceived size= size on retina +depth cues –>ecological validity
critical evaluation of constructivism:
it is the only one to explain illusions, but doesn’t explain why the top would influence the bottom.
patient SB:
example for constuctivism, gained sight through cornea transplant and although sensations were normal, emotional responses to sensations were traumatic which indicates top down influence
blindsight=
damage to v1( occipital lobe), cortically blind but can guess above chance-due to preserved pathways that bypass v1
prosopagnosia=
damage to fusiform gyrus (temporal lobe)- disorder of face perception- can date damage using famous faces
spatial neglect=
damage to posterior parietal cortex, results in disorder of attention to stimuli on one side
