Chapter 5 Flashcards
inverse projection problem
task of determining object responsible for a particular image on retina. Involves starting with retina and extending rays out to object
viewpoint invariance
ability to recognize an object seen from different viewpoints
perceptual organization
process by which elements in our environment become perceptually grouped to create our perception of objects
grouping
process by which visual elements are put together into units or objects
segregation
process of separating one area or object from another
gestalt
configuration “how are configurations formed from smaller elements?”; Gestals psych rejected “adding up” and experience
structuralism
pre-Gestalt - Wundt, Leipzig 1879; distinguished between sensations (elementary processes that occur due to stimulation of senses analagous to atoms of chemistry) and perceptions (complex conscious experiences such as awareness of an object); combination of sensations that form perceptions influences by past experiences
illusory contours
pac man - triangle observed, no edges present, can not be explained by sensation because no sensation along contours
apparent movement (stroboscope)
wertheimer - how could the illusion be saw be created from sensations? movement can be explained by perceptions due to dark portion, whole is different than the sum of parts; movement perceived but not real 1) image flashes on and off, 2) period of darkness (franction of a second), 3) 2nd image flashes on and off - perceptual system adds image of movement during period of darkness
organizing principles
Gestalt principles - determine how elements in a scene are grouped
Principle of good continuation
pts that when connected result in straight/smooth lines are seen as belonging together and tend to be seen in the way that follows the smoothest path (surfaces too - partially obscured objects seen as continuing beyond cover)
Pragnaz, principle of good figure/simplicity
every stimulus is seen in a way that resulting structure is as simple as possible
principle of similarity
similar things appear to be grouped together
principle of proximity/nearness
things that are near each other appear grouped together (seeing the flock)
principle of common region
elements within same region of space appear to be grouped together
principle of uniform connectedness
connected region of similar visual properties (lightness, colour, texture, motion) perceived as one unit
perceptual segregation
perceptual segregation of one object from another
figure-ground segregation
- figures are more thinglike than background, more memorable
- figure is seen as in front of ground
- near borders shared with figure ground is seen as unformed material and seems to extend behind shape
- border seems to belong to figure
image based factors of figure-ground segregation
- areas lower in field of view are more likely to be perceved as figure
- more likely to be perceived as figures when on convex side of border
subjective factors of figure-ground segregation
- good continuation overrides effects of past experiences
- figure must be separated from ground before we assign meaning
scene
view of real world environment with background elements and multiple objects arranged in a meaningful way relative to eachother and background
gist
general description of a type of scene, very rapid
persistence of vision
visual stimulation continues for 250 ms after stimulation ends
visual masking system
blocks persistence of vision - random pattern shown that covers original image
global image features
- degree of naturalness
- degree of openness
- degree of roughness
- degree of expansion (convergence of paralell lines)
- degree of colour
holistic and rapid
physical regularities
regular occuring physical properties of the environment
- vertical and horizontal lines
- objects often homogeneous in colour and contrasting to nearby objects
- light from above assumption
semantic regularities
meaning of a function/scene, characteristics associated with functions carried out in different types of scenes
Theory of unconscious inference
Helmhotlz; some of our perceptions are result of unconscious assumptions made about environment
likelihood theory
we perceive object that is most likely to have caused pattern of stimuli we perceive (deals with ambiguity of perceptual stimulation)
Bayesian inference
quantification of inference that includes probability
binocular rivalry
one stimulation/image to each eye, can not perceive both at once
