psych of perception chapter 10 Flashcards
Müller-Lyer illusion
The Müller-Lyer illusion is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they tend to place it more towards the “tail” end.
misapplied size constancy scaling
size constancy normally helps us maintain a stable perception of objects by taking distance into account
- misapplied size constancy scaling refers to a principle that is proposed by Richard Gregory, that when mechanisms that help maintain size constancy in the three-dimensional world are applied to two-dimensional pictures, an illusion of size sometimes results
The Ponzo (or railroad track) Illusion
both animals are the same size, and so have the same visual angle, but the one on top appears longer. According to Gregory’s misapplied scaling explanation, the top animal appears larger because of depth information provided by the converging railroad tracks that make the top animal appear farther away
The Ponzo (or railroad track) Illusion
both animals are the same size, and so have the same visual angle, but the one on top appears longer. According to Gregory’s misapplied scaling explanation, the top animal appears larger because of depth information provided by the converging railroad tracks that make the top animal appear farther away
the Ames room
the Ames room causes two people of equal size to appear very different in size, this perception occurs even though both women are actually about the same height. The reason for this erroneous perception of size lies in the construction of the room. The construction of the room causes the woman on the left to have a much smaller visual angle than the one on the right.
size-distance scaling
link between size constancy and depth perception has led to the proposal that size constancy is based on a mechanism called size–distance scaling that takes an object’s distance into account.
size-distance equation
S = K ( R x D )
According to the size–distance equation, as a person walks away from you, the size of the person’s image on your retina (R) gets smaller, but your perception of the person’s distance (D) gets larger. These two changes balance each other, and the net result is that you perceive the person’s size (S) as remaining constant.
(S is perceived size, K is a constant, R is object’s retinal size, and D is the distance)
the moon illusion
the moon appears larger on the horizon than when it is higher in the sky
cue approach to depth perception
when the image is two-dimensional, we still need to explain how we get from flat image on the retina to a three-dimensional scene perception. One way researchers have approached this problem is to ask what information is contained in this two-dimensional image that enables us to perceive depth in the scene. this is called the cue approach to depth perception
occlusion
the object that is partially covered must be at a greater distance than the object that is covering it
(near objects cover far objects)
pictorial cue
oculomotor cues
cues based on our ability to sense the position of our eyes and the tension in our eye muscles: convergence and accommodation
convergence
inward movement of the eyes when we focus on nearby objects
accomodation
the shape of the lens changes when we focus on objects at different distances
to focus on the objects which is further, lens gets thinner, for objects near by - thicker
monocular cues
cues that work with only one eye
pictorial cues
pictorial cues are sources of depth information that can be depicted in a picture, such as the illustrations in book or the image on the retina
relative height
objects that are below the horizon and have their bases higher in the field of view are usually seen as being more distant
* when objects are above the horizon, like the clouds, being lower in the field of view indicates more distance
relative size
when two objects are of equal size, the one that is farther away will take up less of your field of view than the closer one
perspective convergence
when parallel lines extend out from an observer, they are perceived as converging - becoming closer together - as distance increases
(parallel lines coming-together)
familiar size
we use the cue of familiar size when we judge distance based on our prior knowledge of the sizes of objects
atmospheric perspective
occurs when more distant objects appear less sharp and often have a slight blue tint, the farther away an object is, the more air and particles (dust, water droplets, airborne pollution) we have to look through, making objects that are farther away look less sharp and bluer than close objects
texture gradient
elements that are equally spaced in a scene appear to be more closely packed as distance increases
shadows
indicate where objects are located
motion-produced cues
emerge when the observer is walking
motion parallax
occurs when, as we move, nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly
why motion parallax occurs?
image of near object and a far object move across the retina as the eye moves from position 1 to position 2, objects closer to perceiver moves further distance
deletion and accretion
as an observer moves sideways, some things become covered (deletion), and others become uncovered (accretion)
binocular depth information
the differences in the images received by our two eyes
binocular disparity
depth perception created by input from both eyes
* difference in images from two eyes
horopter
imaginary sphere that passes through the point of focus
*objects on the horopter fall on corresponding points on the two retinas
corresponding retinal points
the places on each retina that would overlap if one retina could be slid on top of the other
noncorresponding points
objects that do not fall on the horopter fall on noncorresponding points, these points make disparate image
relaitive disparity
the difference between two objects’ absolute disparities
angle of disparity
visual angle between the images of an object on the two (2) retinas
- when images of an object fall on corresponding points, the Angle of disparity is zero, when images fall on non-corresponding points, the Angle of disparity indicates the degree of non-correspondence
absolute disparity
amount of absolute disparity indicates how far an object is from the horopter, greater disparity is associated with greater distance from the horopter
stereopsis
the impression of depth that results from information provided by binocular disparity
correspondance problem
How does the vi- sual system match the parts of the images in the left and right eyes that correspond to one another?
visual angle
angle of an object relative to the observer’s eye, it depends on the size of the stimulus and on its distance from the observer
size constancy
our perception of an object’s size remains relatively constant, even when we view an object from different distances, which changes the size of the object’s image on the retina
Emmert’s law
the farther away an afterimage appears, the larger it will seem
this result follows from size–distance scaling equation, S = R x D
angular size contrast theory
theory of the moon illusion is the angular size contrast theory, which states that the moon appears smaller when larger objects surround it
thus when the moon is elevated, the large expanse of sky surrounding it makes it appear smaller. However, when the moon is on the horizon, less sky surrounds it, so it appears larger
apparent distance theory
according to apparent distance theory, the moon on the horizon appears more distant because it is viewed across the filled space of the terrain, which contains depth information; but when the moon is higher in the sky, it appears less distant because it is viewed through empty space, which contains little depth information
