Visual Perception Flashcards
what disease did Dr. P have?
Visual form agnosia
what is visual form agnosia
able to describe objects in great detail but unable to recognize the objects when they are visually presented
what is the first stage of the perceptural process
internal or external to the subject?
examples?
stimulus/environment stimulus is the first stage of the perceptural prcoess and is external to the subject
ex. tree, car, bike
what is the 2nd stage of the perceptual process
light is reflected from the stimulus and enters the eye
what happens to the stimulus in the 2nd stage is called the _____
principle of transformation
-the environmentla stimulus is transformed (or changed) in order to be perceieved
what is the 3rd stage of the perceptual process
the receptor process
light is converted to an electrical signal that propagates other retinal layers
what is the principle of representation
the refelcted light is focused on the retina and therefore the environmental stimulus (external stim) is now represented internally to the subject
everything a person perceives is based not on direct contact w/ the stimulus but on the …..
representation of the stimulus on the receptors and on activity in the nervous system
what is the 4th stage
neural processing
-signal generated by the photoreceptors is transmitted to and transformed by neurons (bipolar, ganglion, P, M, and K cells, simple and complex cells in the primary visual cortex)
what is the 4th stage’s signal further processed by
neurons w/in the brain
-ex. ventral and dorsal stream
after the signal has been trasmitted and transformed by the neurons of the nervous system the next stages in perceptual prcoess take place, what are these called
behavorial responses
w.o _____ you cannot recognize or take actino after perception
knowledge or experience
perception => recognition => ____
action
what are the 3 behavorial responses
- perception which is conscious awareness of a stimulus
- recognition which is the categorization of the stimulus
- action which involves usually motor activities
when the stimulus is a tree…
- the light is reflected, transformed, and focused on the ____
- the ______ react to light and generate a signal
- once the neurons process and transform this signal we. perceive an ____
- we ____ the object as being a tree (categorize it)
- we take _____
- retina
- photoreceptors
- object
- recognize
- action
where can knowledge be from
- knowledge is the info that a subject brings to any situation
- knowledge may have been acquired over many years or just recently
what are the 2 types of perceptural processing
- bottom-up processing
2. top-down processing
what is bottom up processing also known as
aka data based processing
what is bottom up processing
says that the perception influences behavior
-based on the stimuls’ image that reaches the photoreceptors
-
what is the starting point of perception? why?
bottom-up processing
bc w/o photorecptor activation there is no perception
what is top down processing also known as
knowledge-based processing
what is top down processing based on
prior knowledge
what does the top-down processing theory state
that perception is influenced by cognition
ex, wandering around at night
where does bottom-up processing start at
the photoreceptors and propagates towards the brain
where does top-down processing start at
starts at the brain and influences lower perceptual processes
ex. knowledge influences recognition
how often does top-down processing get used in perception
for simple tasks and stimulus, usually bottom-up processing is sufficient
- as the stimui get more and more complex, then top-down processing becomes the major player
ex. perception of a scene is top down
when it comes on perceiving objects we need to go beyond the retinal image as it is ____
ambiguous
is the light and dark pattern that a scene creates on the retina enough to determine what’s out there?
nope
once we know the object’s ___ and ____ it’s a simple problem to find the retinal image
size and geomtrey
the perceptual system is not concerned on calculating the retinal image. what is it concerned on determing?
concerned on determining the real object for a given retinal image
determining the real object for the given retinal image is known as what
inverse projection problem
can computers solve the inverse projection problem? why/why not?
no. they can’t separate objects w/ the same visual angle
why is the perceptual system able to recognize objects that are not in focus
based on prior knowledge of these objects
the perceptual system is able to differentiate objects that share the same retinal image, recognize blurred or hidden objects, and perceive as the same, objects that are viewed from diff viewpoints. how is this achieved
perceptual organization
what are the 2 different mechanisms that perceptual organiziaiton has
- grouping
2. segregation
what is grouping
the ability of the perceptual system to ‘put together’ visual events
ex. when you are looking at indiv windows you can put them together to form a buildig
what is segregation
the ability to distinguish objects from other objects
ex. when you look at boston’s skyline, you can tell one building is diff from the other
are grouping and segregation together or separate?
they work together
what does gestalt mean
whole or complete
- looks at the big picture, not indiv parts
- laws for gropuing and segregation are used
what are gestalt’s grouping principles
simplicity similiarity proximity continuity common fate closure connectedness
what is the principle of simplicity also known as
principle of good figure or pragnanz
what is the principle of simplicity
fundatmental principle of gestalt psych
-every stimulus is seen in such a way that the resulting structure is as simple as possible
OR
-reality is organized or reduced to the simplest form possible
what is the principle of similarity
grouping objects that are similar
ex. rows of red and blue
- principle applies to grouping bc of similiar color, shape, size or orientation
what is the principle of proximity
things that are near each other appear to be grouped together
ex. one row of stars vs 3 groups of 2 stars each
what is the principle of continuity
we tend to see complex stimuli as being composed of smooth, continuous patterns that overlap
-lines tend to be seen in such a way as to follow the smoothest path
what is the principle of common fate
thigns that move in the same direction appear to be grouped together
ex. flock of birds as a whole and not as a hundred of indiv. birds
what is the principle of closure
things that are w/in the same region or space appear to be grouped together
what principle does the principle of closure override
principle of proximity
what is the principle of connectedness
a connected region of the same visual properties (ex. color, brightness, texture or motion) is perceived as a single unit
what principle does the principle of connectedness overpower
principle of proximity
the grouping principles tell us that we create perceptions of objects based on ____
assumptions
assumptions are _____ and are so obvious bc we have experience
unconscious
the assumptions are nothing less than the …
basic operating principles of our perceptual system
what is the segregation problem referred to
the ground-figure segregation
bc what we perceive as an object usually stands from its background
what is border ownership
the border separating the figure from the ground belongs to the figure
