Module 03: Perception Flashcards
distal stimulus
real world objects to be perceived
proximal stimulus
retinal image (upside down and backwards) of object, reception of info and its registration by sense organ
percept
recognition of an object, meaningful interpretation of proximal stimulus
form perception
segregation of while display into objects and background (think of reversible figures like the white vase and black faces)
subjective contours
complex display to simplifying interpretations (think triangle example)
what are the 5 principles of gestalt psychology and explain them
proximity – group things that are close together
similarity – grouping objects that look the same
connectedness/continuation – group objects whose contours form cts straight or curved line
closure – mentally fill gaps to complete picture
common fate – move together, group together
law of pragnanz
out of all ways to interpret displays, tend to select the organization that yields the simplest and most stable shape and form
bottom up processes
data driven
small bits of info from environment, combined to form percept
perception from info in distal stimulus
relatively uninfluenced from previous experience/learning
what are some issues with bottom up processing
context effects: both accuracy and length of time needed to to recognize objects vary with context
expectation effects: similar to context effects but with expectations
bottom up processing can’t really explain this
what are three examples of bottom up processing
template matching, feature analysis, prototype matching
describe template matching
templates: previously stored patterns
an unknown incoming pattern is compared to all templates and identified by template that best matches it
the perceiver does not know what the object is until it is matched to a template
what are some issues with template matching idea
need to have stored an impossibly large amount of templates
humans are capable of recognizing NEW objects
patterns recognized as more or less the same thing even when they differ a lot
describe feature analysis
breaking down into features – using recognition of parts to infer the whole
(whole into parts)
feature not present => detectors do not respond as strongly
what was Neisser’s visual search task and what were the findings
given an array of letters, participants respond if they detect a presence of a certain letter
took longer to find Z than Q in arrays with letters that look like Z and vice versa
(same with auditory things)
what is selfridge’s pandemonium idea
‘demons’ are feature detectors
first level scans input, different feature demons scream louder when the feature is better matched
higher levels then scan output from lower levels
what are some issues with the feature analysis idea
how do we define a feature?
how do we know what features to use to perceive the object?
list of possible features could be huge
what is a protoype
idealized representation of some objects or events
describe prototype matchiing
matching input to a prototype
ex. prototype of dog would be a very typical dog
stimulus could be an approximate match, more flexibility than templates
object is perceived when a match is found
takes into account object’s features AND the relationships between them
top down processing
perceiver’s expectations, theories, or concepts guide the selection and combo of the info in the pattern recognition process
relies on expectation and knowledge/past leaning and context
what are the three sketches of the jumbled vs regular kitchen scene
primal sketch – areas of brightness and darkness in 2D image and localized geometric structure - boundaries between areas
2.5D sketch – derives info about what surfaces are and how they are position in depth relative to viewpoint - relies on bottom up processes
3D sketch – recognition of objects and understanding the meaning of the scene (uses knowledge and specific expectations)
what is change blindness
inability to detect changes to an object or scene
what experiment studied change blindness
simons and levin
having a conversation, person walks through a door and replaced
goes unnoticed 50% of the time
visual percepts not precise copy of our visual world
what is the word superiority effect
letters are easier to perceive in familiar context (words) than unfamiliar or no context
study that looked at the word superiority effect
identify which 2 letters was briefly presented onscreen and was told the 2 choices the letter could be
sometimes displayed a word, or a random mix of letters
participants more accurately identified letters presented in the context of words
what is the missing letter effect
attention is focused more on moderately familiar content words than highly familiar function words
ability to detect letters enhanced by word familiarity when words appear in isolation but inhibited by increased familiarity or role when a word appears in real text
what is the connectionist model of word perception
input is processed at several different levels
each level of processing assumes to form a representation of info at different level of abstraction
lines between nodes represent connections (excitatory or inhibitory)
excitatory links, the two nodes suggest each other
perception of a word – activation of that word node also activates the nodes corresponding the the letters within that word
without word context, node for individual letter is less active so perception takes longer
what is the neuroscientific perspective on word perception
words and pseudowords produce different PET scans from those produced when participants saw letter strings or false fonts
different brain areas active for different types of stimuli
PET activity in visual cortex of both hemispheres
what is the constructivist approach to perception
people add to and distort info in proximal stimulus to obtain a percept
what is direct perception
direct acquisition of info from the environment
perceive objects affordances: acts/behaviours permitted by objects, places and events
light hitting retina contains highly organized info that requires little to no interpretation
what are the 2 types of visual agnosia
apperceptive agnosia
associative agnosia
describe apperceptive agnosia
can process a limited amount of info
can see contours or outlines but have difficulties categorizing objects
some can’t name objects
associated with the right hemisphere
describe associative agnosia
can match objects and copy drawings but do this very slowly and carefully
can be distracted by small details
cannot readily name the objects they have seen and drawn
correlated with bilateral damage to particular regions of brain in the cerebral hemisphere
describe prosopagnosia
impaired explicit face recognition but preserved implicit face recognition
damage in the right hemisphere
what is unilateral neglect
causes patient to virtually ignore stimuli on opposite side of damage
damage to the parietal cortex
describe capgras syndrome
impaired implicit face recognition but preserved explicit face recognition
(no galvanic skin response, claims person is an imposter)
