our body's position in space relative to other objects
What are the sources of depth perceptual information?
monocular cues, oculomotor cues, and binocular cues
What is occlusion?
cue to relative depth order in which, for example, one object obstructs the view of part of another object
What is the nonmetrical depth cue?
gives us the relative orderings of occluders and occludees
What is the metrical depth cue?
provides information about distance in the third dimension
What is projective geometry?
describes how the world is projected onto a surface
What is relative size?
determining that smaller things are farther away even though they just appear that way based on their size
What are the pictorial cues?
relative size, occlusion, shading/shadows, linear perspective, parallel lines
What is aerial perspective?
objects farther away are subject to more scatter and appear fainter and less distinct
What is texture gradient?
depth cue based on the geometric fact that items of the same size form smaller images when they are farther away
What is relative height?
observation that objects at different distances from the viewer on the ground plane will form images at different heights in the retinal image (objects farther away will be seen as higher in the image)
What is linear perspective?
depth cue based on the fact that lines that are parallel in the 3-dimensional world will appear to converge in a 2-dimensional image
What is motion parallax?
when geometric information obtained from an eye in two different positions at two different times is similar to the information from two eyes in different positions in the head at the same time (observer moves while objects in visual field remain still, visual objects move slower the farther away they are from observer)
What is accommodation?
the process by which the eye changes its focus to clearly see objects near or far
What is convergence?
the ability of the two eyes to turn inward to focus an object that is closer to the eyes (typically focused on the fovea of each eye) (convergence reduces the disparity of a feature to nearly zero)
What is divergence?
the ability of the two eyes to turn outward to focus an object that is farther away from the eyes (typically focused on the fovea of each eye) (divergence reduces the disparity of a feature to nearly zero)
What are the oculomotor cues?
divergence and convergence which are performed through accomodation
Who has the largest binocular visual field?
What is the horopter?
the location of objects whose images lie on corresponding points around an imaginary circle that runs through the two eyeballs (surface of zero disparity)
What is diplopia?
double vision (stimuli visible in both eyes but falling outside of Panum's fusional area will appear diplopic)
What is crossed disparity?
sign of disparity created by objects in front of the plane of fixation (the horopter), images of objects located in front of the horopter appear to be displaced to the left in the right eye and to the right in the left eye
What is uncrossed disparity?
sign of disparity created by objects behind the plane of fixation. images of objects located behind the horopter will appear to be displaced to the right in the right eye and to the left in the left eye
What is binocular rivalry?
occurs through the use of a stereoscope (seeing one image in one eye and another image in another eye at the same time) binocular vision goes into battle to decide which image to focus on
What is free fusion?
the technique of converging (crossing) or diverging the eyes in order to view a stereogram without a stereoscope
What is size constancy?
objects of the same physical size produce retinal angle sizes with increasing distance from the observer. Thus, smaller images are perceived to be more distant
What does emmert's law say?
perceived size = image size X perceived distance
What is shape constancy?
the shape will remain unchanged even though there are changes in its retinal image produced by changes of orientation, distance to relative to the viewer
What does gregory's depth theory state?
based on the direction of the visual cues in the image, one line will be misinterpreted as being longer than the other (arrow pointing up, shorter line; arrow pointing down, longer line)
What is the moon illusion?
the moon appearing more distant on the horizon compared to when it is over-head