Perception Flashcards
multisensory illusion
change in auditory perception from visual input
- top down processing
- McGurk
Information compression
millions of photoreceptors, 100x fewer ganglion cells, optic nerve, brain
-what we see is not all there is
Fovea
small area ont he central part of visual field
-where most cones are
Contralaterality
- Each eye’s optic nerve transmits info to both hemispheres
- L visual field of both eyes transmitted to the right hemisphere
- opposite on the other side
Primary Visual Cortex
- within occipital lobe
- detects size, color, light, motion, dementions
Visual Association Areas
- w/i occipital lobe
- interprets and understands visual info, assigns meaning to input
Ventral Pathway
- “WHAT” pathway
- occipital to temporal lobes
- shape, size, visual details
Dorsal Pathway
- “WHERE” pathway
- Occipital to Parietal Lobes
Blindsight
- damage to primary visual cortex
- patients report no awareness of stimuli in damages area
- can answer questions about things they “didn’t see”
- they perceive something w/o knowing it
subliminal priming
test the effect of stimuli presented w/o conscious awareness
-stimuli below the threshold of awareness
backwards masking
- present target stimulus
- mask that target with another stimuli
- the masking reduces visibility,
- target info is unavailable to conscious report, but can still influence processing
change blindness
- not all of perceptual environment reaches our awareness
- interaction between attention and perception
3 examples of the fact that we do not perceive all the information in our environment
Ponzo Illusion
- World is lit from above illusion
- Ebbinghaus illusion
Steps of Early Visual System
1) Light enters eye and is focused onto the retina
2) Photoreceptors in retina convert light to electrical activity
3) electrical signal sent to bipolar then ganglion cells
4) signal exits the eye thru optic nerve
Visual Agnosia
Dissociation between being able to see visual features and interpreting those features
-location of damage decides what features are not recognized
Prosopagnosia
- visual agnosia
- inability to recognize faces
- damage to fusiform gyrus
- acquired or congenital
Apperceptive Visual Agnosia
-failure to recognize objects, because of perception problems
Associative Visual Agnosia
- inability to associate visual forms w/ intended meaning
- cannot name objects, draw objects from memory or match object to function
What we can learn from visual illusions
- top down processing involved in vision
- info lost moving from eye to brain
- bring schemas of understanding to perception
texture gradients
the density of a gradient carries info about orientation and distance
topological breakages
- where two textures intersect
- signals edges between objects
scatter reflection
how widely light scatters off an objects surface
-cues to the relative roughness of surfaces
affordances
- Gibson
- We perceive objects in terms of the functions that can performed with them
- ball affords bouncing
Template matching theory
match pattern seen to templates of previous objects
- match leads to identification
- how do we match objects that DONT match the template
Prototype Theory
compare the seen configuration with a standard configuration
-if close enough, identify object
Multiple Trace Memory Model
- a probe (seeing an object) activates secondary memory traces
- activated memory returns an echo to primary memory (containing general impression of objects)
Feature detection theory
-Pandemonium model: feature demons, cognitive demons, decision demons
Hintzman
multiple trace memory model of object recognition
Selfridge
Pandemonium model
Recognition by component
- combination of feature theory and prototype theory
- all objects reducible to combination of some 36 geons
Top down processing
- color recognition (the dress)
- letters in context (able to read sentences when jumbled)
- GESTALT
Gestalt Approach
-the perceived whole is greater than the part
Organizing Gestalt Principles
1) Experience
2) Proximity
3) Closed Forms
4) Good Contour
5) Similarity
6) Common Movement
principle of experience
figure ground segmentation- we know something is in foreground something is in background
principle of proximity
things that are close together are judged as belonging together
principle of closed forms
we see shapes in terms of closed forms, enclosed wholes
principle of good contour
perceive objects as continuous when expected to continue
principle of similarity
organize objects based on similarity
