Depth and size percetion Flashcards
relationship between depth and size
depth and size are deeply related because how big an object looks can be affected by how far away an object is. How big an object appears can affect how big it appears.
How do we perceive depth?
We percieve depth using
Oculomoter cues (cues based on our ability to sense the position and state of our eyes.)
Monocular cues. (cues based on the visual information available within the eye)
Binocular cues. (cues that depend on visual information within both eyes)
Oculomoter cues
two main ones:
- Binocular convergance: the amount of inward rotation your eyes have to do in order to focus on an object. increased tension the closer an object comes to face.
Accommodation: When we try to focus on distant objects, the ciliary muscles strech the eye lens, making it thinner and changing the focal length. vice versa.
Monocular cues:
Accomadation: also a monocular cue.
Pictoral cues: occlusion, relaive height, familiar and relative size, perspective convergence, atmospheric perspective, texture gradient, shadows.
Movement based cues: Motion parallax and deletion and accretion.
Binocular disparity
because the left and right eyes are offset relative to each other, they see the world from different angles. The relative allignment of an object changed depending on if both or just one eye is open.
correspondence problem
retinal images can be ambiguous, if there are multiple identical objects in the scene it can be hard to figure out which images in the left retinal image should be associated with which images in the right retinal image.
how do we perceive size- angular size
angular size is just the visual angle in the object subtends. the closer an object is to person, the larger its angular size.
how do we perceive size- size constancy
size constancy= objects apparent size doesn’t rely on its physical distance. When the object is far away, it appears to be the same size as when it is closer. To acheive this, the observer needs to consider both the size of the retinal image, and the distance of the object
size illusions
Size illusions usually occur because people mistake the distance of an object so that it appears larger or smaller than it really is. If an object appears closer than it really is, it will appear smaller than it really is and vice versa.
Ames Room
The trapezoidal room is designed to make it look not perpendicular, when it really is, so that one person appears very big (because they are close to the peephole), and one occurs small because of how far away they are from the peephole.
Holway and Boring (1941)
Holway and Boring investigated an observer who could view the test circle down one corridor and the comparison circle down the other. They were of different sizes, however they were presented at different distances, so their angular size was the same. Their task is to adjust the size of the comparison circle to match the size of the test circle.
findings of Holway and Boring
C1- observers determine the depth of the test patch using binocular disparity, motion parallax and shadows.
C2- observers viewed the etest circle with one eye to remove binocular disparity cues.
C3- observers viewed the circles through a peephole to remove motion parallax cues.
C4- drapes were added to remove shadows.
findings: When there are sufficient depth cues, the size of the test patch can be accurately estimated. when there are no sufficient depth cues, the apparent size of the test patch is bias towards to visual angle.
