EXAM 2 Flashcards
what is occlusion?
one object is in front of another
what is cue theory?
connection between cue and depth through previous experience with the environment
what are the different types of cues that signal depth in a scene?
1) oculomotor - position of our eyes and tension in eye muscles
2) monocular - visual info that can use only one eye
3) binocular - visual info that needs both eyes
what is convergence?
our eyes moving inward when looking at something close by
what is accommodation?
change in our lens when we focus on objects at different distances
what are the three types of monocular cues?
1) accommodation
2) pictorial cues
3) movement based cues
what are pictorial cues?
sources of info that can be depicted in a picture (ex. can be seen through images)
what are movement based cues?
sources of depth info created by movement
what is relative height?
objects near the horizon appear further away
what is familiar size?
judging distance based on our previous knowledge of an object
what is relative size?
what two objects are equal size, the one farther away will take up less of your view
what is perspective convergence?
ex. parallel railroad tracks appear to converge in the distance
what is atmospheric perspective?
distant objects appear less sharp than nearer objects
what is texture gradient?
elements being spaced more closely appear farther away
what are the two types of motion produced cues?
motion parallax and deletion/accretion
what is motion parallax?
when we move, nearby objects move very quickly and distant objects move more slowly
what is binocular depth info?
two-eyed depth perception that involves both info from the left and right eye
what is stereoscopic vision?
different viewpoints for the two eyes
what is stereoscopic depth perception?
depth perception created by input from both eyes
(ex. when looking at 3D movies, the info from our left and right eyes are slightly different)
what is strabismus?
visual system suppresses vision in one eye to avoid double vision
what is binocular disparity?
difference in the image on the left and right retinas
what is corresponding retinal points?
points on the retina that would overlap if the eyes were superimposed on each other
(ex. if something falls on the horopter, they are on corresponding retinal points)
what are non corresponding points?
images of objects that DO NOT fall on the horopter
what is absolute disparity?
how far an object is away from the corresponding point
what is the angle of disparity?
visual angle between the image of an object on the two retinas
(difference between what is on the horopter and what isn’t on the horopter)
-angle of disparity is greater for objects at a greater distance from horopter
what is crossed disparity?
image that appears BEFORE the horopter
(right image on left eye, left image on right eye)
what is uncrossed disparity?
image that appears AFTER the horopter
(left eye sees image on the left side)
how do we determine if the absolute disparity is crossed or uncrossed?
we can see if an object is in front of or behind the horopter
what is stereopsis?
relationship between disparity and what observers perceive
what is the correspondence problem
determining corresponding points based on object features can’t be the whole answer to the correspondence problem
what are binocular depth cells/disparity selective cells?
cells that respond to disparity in V1 and respond best when stimuli in the left and right eyes create a specific amount of disparity
what is the stimulus-perception relationship?
the relationship between binocular disparity and the perception of depth
what are frontal eyes?
overlapping fields of view, can use disparity to perceive depth, provides good stereoscopic depth perception
-ex. humans and cats
what are lateral eyes?
can use disparity in small overlap area to perceive depth, less bincoular disparity, wider field of vision
-ex. bunnies
what is the visual angle?
angle of an object relative to the observer’s eye
-depends on both the size of the stimulus and its distance from the observer
-when something comes closer, both the retinal image and visual angle increases
what is size constancy?
perception of an object’s size is relatively constnat even when we view the object from different distances
what is the size constancy formula?
S = K (R * D)
-S is object’s perceived size
-K is constant
-R is the size of the retinal image
-D is perceived distance
what is Emmert’s law?
relationship between the apparent distance of an afterimage and its perceived size
-the farther away an afterimage appears, the larger it will seem
what is the Muller-lyer illusion?
right vertical line appears longer than the left vertical line, even though they are both the same length
what is the misapplied size constancy scaling?
distance between the outward facing fins appears enlarged compared to the distance between inward facing fins
what is the conflicting cues theory?
our perception of line length depends on two cues
1) actual length of the vertical limes
2) overall length of the figure
what is the ponzo illusion?
an example of misapplied scaling explanation
ex. top animal appearing bigger because of depth info that tells us it’s farther away
what is the ames room?
two people of equal sizes that appear very different sizes
(the perceived distance is the same, the retinal image is smaller for the smaller person, and the perceived size is smaller)
what is the ecological approach to perception?
how movement creates perceptual info that helps people move within the environment
what is the gradient of flow?
info to determine his or her speed of movement
-a gradient is created by movement of an observer through the environment
what is the focus of expansion?
absence of flow at the destination point
what is invariant info?
info that remains constant regardless of what the observer is doing or how the observer is moving
what are affordances?
information that indicates how an object can be used
-ex. a chair affords sitting and a pen affords writing
what is action affordance?
responding to an object with both affordance and action
-ex. a hammer is for pounding something and the motion of hammering something
what is visual direction strategy?
people point their body toward their goal
-ex. walking toward a tree and having a dog block your path, so you have to walk around the dog
what is spatial updating?
people and animals keep track of their position within a surrounding environment
what is wayfinding?
perceiving objects in environment, remembering objects, their relation to overall scene, and knowing when to turn and in what direction
what are the different types of landmarks?
1) decision point landmarks - objects at corners where the participant turns
2) non decision point landmarks - objects located in the middle of corridors that provided no critical info
what are cognitive maps?
mental map of the spatial layout of an area of the environment
what are place cells?
neurons that fire only when an animal is in a certain place in the environment
what are grid cells?
provide info about the direction of movement, may be able to code distance and direction info
how are the ventral and dorsal stream used in action
ventral (what) and dorsal (where/how/action)
-ex. identifying bottle among other things on table (ventral what pathway)
-ex. reaching for the bottle (dorsal action pathway)
what is the parietal reach region (PRR)?
region contains neurons that control not only reaching but also grasping
what is the visuomotor grip cell?
neuron that initially responds when a specific object is seen
-responds as hand movements grip object
what is proprioception?
ability to sense body position and movement
what is a mirror neuron?
a neuron that responds both to acting on an action and watching someone do an action
what is the action specific perception hypothesis?
people perceive their environment in terms of their ability to act on it
-ex. batters who hit well perceive the ball as bigger
what is attention?
process which results in certain sensory info being selectively processed over other info
what is overt attention?
when you move your eyes from one place to another to focus a particular object or location
what is covert attention?
when you attention shifts without moving your eyes
what is the broadbent’s filter model of attention?
attention makes the attended stimulus avaliable for more processing
what is the feature integration theory (FIT)
1) preattentive stages - features of the object analyzed unconsciously
2) focused attention stage - attention becomes involved and conscious perception occurs
what is the difference between fixation and saccadic eye movement?
fixation is causing your eyes briefly, saccadic is rapid eyes movements
what is predictive remapping of attention?
attention begins to shift toward the target just before the eye begins moving towards it
what is visual salience?
markedly different from their surroinding, whether in color, contrast, movement, or orientation
what is attentional capture?
properties of a stimulus grabbing attention
what is a saliency map?
which regions are visually different from the rest of the scene
-regions of greater visual salience are denoted by brighter regions in the saliency map
what is a scene schema?
people look longer at things that seem out of place
what are task demands?
tasks require shifting attention to different places as the task unfolds
how does attention influence appearance?
attention affected the perceived contrast between the alternating light and dark bars
what is the FFA region for?
the fusiform face area is the region of the cortex that responds strongly to faces
what is the PPA region for?
the paragippocampal place area responds best to houses, landmarks, and indoor/outdoor scenes
how are attention and neural activity correlated?
patterns of activity within the visual cortex changed depending on where a participant was directing their attention
what is inattentional blindness?
stimulus that is not attended to is not perceived, even though someone is looking directly at it
what is change blindness?
difficulty in detecting differences between two visual stimuli that are presented one after another
what is the inverse projection problem?
image projected onto a surface doesn’t always accurately depict what is out there in the environment
what is viewpoint invariance?
ability to recognize an object seen from different viewpoints
what is grouping?
elements in the visual scene are “put together” into coherent units
what is segregation?
separating one area or obejct from another
what is sensation?
elementary process that occur in response to stimulation of the senses
what is perception?
complex conscious experiences such as awareness of objects
what is apparent movement?
movement that is perceived but nothing is actually moving
(ex. combination of one light flashing followed by another light looks like movement)
what are illusory contours?
when no physical contours are present
what is the gestalt principle of pereceptual organization
perception depends on the number of principles of perceptual organization
what is the principle of good continuation?
points that when connected results in straight or smoothly curving lines are seen as belonging together
what is pragnanz?
every stimulus pattern is seen in a way that is as simple as possible
what is similarity?
similar things appear to be grouped together
what is proximity?
things that are near each other appear to be grouped together
what is common fate?
things that are moving in the same direction appear to be grouped together
what is common region?
elements that are within the same region of space appear grouped together
what is uniform connectedness?
connected region of te same visual properties such as lightness, color, texture, or motion is perceived as a single unit
what is perceptual segregation?
perceptual separation of one object from another
what are the properties of figure and ground?
figure - more memorable, bored of image
ground - less unform, without specific shape
what is the recognition by components theory (RBC)?
objects are comprised of individual geometric components called geons
what are geons?
geons are 3D shapes like cubes, pyramid, and cylinders
