Form Preception I
GESALT PRINCIPLES
their approach summarized by Koffka :: the whole is other than the sum of its parts
gestalt principles :: laws that describe how we organize visual input. figure-ground segregation, location, proximity, closure, similarity, continuity, common fate, brightness + colour constancy
figure-ground segregation :: ability to determine was aspect of a visual scene is part of the figure + what is part of the background
proximity :: elements that are close together in space tend to belong together
closure :: if there are gaps in the contours of a shape, we tend to automatically fill in those gaps and perceive a whole object
similarity :: tendancy to group together elements that are physicially similar
continuity :: perceive a simple, continous form rather than acomination of awkward forms
common fate :: things that change in the same way should be grouped together
the whole has a perceptual reality of its own, that is different from the component parts
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PATTERN/OBJECT RECOGNITION
bottom-up processing :: features that are present in the stimulus itself guides object recognition
top-down processing :: your own beliefs or expectations are the primary influence for determining what you’re seeing
bi-directional processing :: using both styles of processing
priming :: having participants have expectations top-down processing
biederman's Geon theory :: we have 36 simple geometrical forms stored in memory. using just the 36 geons it’s possible to recognize over 150 million different objects. disproven bc sometimes when there is brain damage a person has trouble differentiating types of fruit, but not types of tools. however, geons possible that geons are processed at a diff level of neural signalling separate from the area of brain damage.
template theory :: we store many diff templates. if exact match is found = familiar object. if no match is found = not familiar. con - would need so much storage of brain
prototype theory :: we store the most typical or ideal example of object. likely we have more than one type of representation for each object, like an ideal prototypical dog and also all the dogs that we are personally familiar with. more flexible bc no need for exact match. con - we can’t categorize unique/specific objects.
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PERCEPTUAL CONSTANCIES
perceptual constancy :: refers to out ability to perceive an object as unchaing even though the visual image that the object produces is constantly changing
shape constancy :: we pweceive objects to have a constant shape, even thgouh the actual retinal image of the shape would change as your point of view changes or as the object changes position in space
location constancy :: an object is perceived to be stationary despite changing location on our retina due to body movements
size constancy :: an object is perceived to be the same size despite the size of its retinal image varying w distance
brightness constancy :: an object is perceived to be the same brightness despite reflecting more or less light onto our retina
colour constancy :: an object has constant colour even thoguh the light stimulus that reaches the retina may change w different illumination conditions
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VISUAL ILLUSIONS
they show us how our experiences and culture influence how we perceive events int he world. they show us that perception is an active process, shaped by prior experiences and not just by the scene immediately in front of us.
muller-lyer illusion :: a misapplicatoin of size constancy. despite the two lines being the same length, one is perceived to be longer
ames room :: a misapplication of size constancy. the irregular shape of the room causes one person to look larger than the other, since we are assuming the room is rectangular