Form Perception Flashcards
What are the Gestalt Principles?
Laws that describe how we organize visual input (believed to be innate, acquired rapidly after birth)
Figure-ground principle
ability to distinguish an object from its background in a visual scene (ie. seeing a vase of flowers against a background of flowers)
Proximity
tendency to group elements that are close together in space
Closure
tendency to fill in gaps in a contour to perceive a whole object (we automatically fill in the parts we can’t see to perceive a single object)
Similarity
tendency to group together elements that are physically similar
Continuity
ability to perceive a simple, continuous form rather than a combination of awkward forms
Common fate
tendency to group together elements that change in the same way (why we can see a camouflage animal once it moves)
Bottom up processing
object recognition is guided by the features that are present in the stimulus; compares every feature to memory
Top-down processing
guided by own beliefs or expectations
Priming effect
experimenter tests how fast subject can read a word when its flashed on the screen, if you tell the participant the next word is an animal, you will see priming effect (word would be recognized faster)
Geon theory
suggests we have representative geons stored in memory (36 different ones)
How does brain injury affect recognition of geons?
brain injury can affect recognition for only certain types of objects (ie. unable to recognize fruits but can recognize tools); if geons were at play, should be able to recognize all types of objects, and not specific category; could be because geons are processed at a different level of neural signaling separate from the area of brain damage
Template theory
suggests we compare objects to templates in memory (similar to exemplar theory); need exact match in order for the connection to occur; otherwise object is stored as another template
Prototype theory
suggests we compare objects to our idea prototype (internal best)
Perceptual Constancy
ability to perceive an object as unchanging even though the visual image produced by the object is constantly changing
Shape constancy
an object is perceived to have a constant shape despite the shape of its retinal image changing with shifts in point of view or change in object position (ie. a door is perceived as rectangular despite its visual change when opening)
Location Constancy
an object is perceive to be stationary despite changing location on our retina due to body movements
Size constancy
object is perceived to be the same size despite the size of its retinal image varying with distance (ie. a friend walking away is not perceived as shrinking in size)
Brightness constancy
an object is perceived to be the same brightness despite reflecting more or less light onto our retina (objects have same brightness whether outside or inside)
Colour constancy
an object is perceived to have a constant colour despite different illumination conditions
Depth cues
indicate the size of an object relative to its distance
Colour cues
indicate the influence of light on an object’s colour
Ames room
illusion that manipulates distance to trick size constancy (that room in niagara falls that makes one person look smaller than the other)
Ponzo illusion
manipulates depth cues to trick size constancy (drawing a triangle/cone to make it look like a road is going straight)
What do visual illusions indicate?
that perception is an active process
Huble and Wiesel Cat Experiment
wanted to see what type of stimuli individual cortical cells responded to; put micro-electrodes into cortex of a cat to record the electrical activity of individual neurons as it shows different things like flashes of light; neurons must respond to stimuli that are more complex than diffused flashes of light; receptive field of simple cells is organized in opponent fashion
Complex cell
responds maximally to a bar of a certain orientation regardless of location; some also respond to specific direction of movement; complex cells are indifferent to the position of light on its receptive field
Hypercomplex cell
responds maximally to a bar of a particular orientation and direction of movement, ending at specific points within the receptive field
Where is topographic organization presevered?
In the visual cortex; neighboring objects in visual field are processed by neighboring areas of brain; not exact because largest amount of cortex is devoted to processing information from the central part of the visual field, which projects onto the fovea; each region of the cortex received some input from a small piece of the visual field, within each region there are cells that analyze specific features of the scene
Where does visual integration begin?
in the extrastriate cortex
When can infants begin focusing on whole objects?
after 2 months of age
When can infants perceive partial forms as whole forms?
3 months of age
What can infants identify at 3 months?
separate objects if objects move independently of one another
What can infants achieve at 5 months old?
they begin to uses cues like colour or texture to distinguish objects
When can infants demonstrate size constancy?
by 4 to 5 months
Critical development periods in kittens
1 month old kittens kept in dark for 3-4 days experience visual degeneration; 1 month old kittens kept in the dark for an entire week or longer suffer severe and permanent visual degeneration
