Perceiving Depth, Size, And Illusions Flashcards
Define
Muller-Lyer illusion
a geometric illusion in which two lines of equal length appear unequal depending on whether angular lines forming arrowheads at each end point toward or away from each other
Define
Crossed disparity
An object closer than the horoptor
Definition
stereo pair of images of random dots which when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level
Random-dot stereogram
What is the range of effectiveness for accommodation and convergence?
Near (0-2m)
Definition
a distorted room that creates an optical illusion
Ames room
Define
Accomodation
change in the shape of the lens when we focus on objects at different distances
Define
Horopter
a line or surface containing all those points in space of which images fall on corresponding points of the retinas of the two eyes
Definition
the gradual reappearance of a moving object as it emerges from behind another object
Accretion
Definition
An object closer than the horoptor
Crossed disparity
Define
Disparity-selective cells
cell in the visual cortex that receives inputs from both eyes and responds only when the binocular disparity is within certain predetermined limits, thus providing a basis for stereopsis
Define
Relative height
objects below the horizon that are higher in the field of vision are more distant
Define
Monocular cues
provide depth information when viewing a scene with one eye
Definition
a theory of visual illusions proposed by R. H. Day, which states that our perception of line length depends on an integration of the actual line length and the overall figure length
Conflicting cues theory
What is the range of effectiveness for relative height?
Moderately far to very far (2-30+m)
Define
Relative size
a perceptual clue which allows you to determine how close objects are to an object of known size
Define
Oculomotor cues
cues based on the ability to sense the position of our eyes and the tension in the eye muscles
Definition
one among a number of illusions where a central aspect of a simple line image—e.g. the length, straightness, or parallelism of lines—appears distorted by other aspects of the image—e.g. other background/foreground lines, or other intersecting shapes
Ponzo illusion
Define
Accretion
the gradual reappearance of a moving object as it emerges from behind another object
Definition
the perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination; binocular vision
Stereopsis
What are the issues with the misapplied size-constancy scaling explanation for the Muller-Lyer illusion?
- The “dumbbell” version shows the same perception even though there are no “corners.”
- The illusion also occurs for some 3-D displays that do not implicate depth.
Definition
inward movement of the eyes when we focus on nearby objects
Ocular convergence
What is the range of effectiveness for relative size?
Near - very far
Define
Familiar size
a visual cue used to judge an object’s distance. It is a monocular cue which means it can provide information about depth peception even by using only one eye
Definition
the gradual occlusion of a moving object as it passes behind another object
Deletion
Definition
cues based on the ability to sense the position of our eyes and the tension in the eye muscles
Oculomotor cues
Definition
any information conveyed to the observer of a two-dimensional image that gives the impression of 3-dimensional image
Pictorial cues
What is one possible explanation for the Ponzo illusion?
One possible explanation is misapplied sizeconstancy scaling.
Define
Stereoscope
a device by which two photographs of the same object taken at slightly different angles are viewed together, creating an impression of depth and solidity
What is relative disparity?
Relative disparity is the difference between the absolute disparity of two objects.
Define
Size-distance scaling
an idea that the perceiver combines the size of object formed on retina and its distance to perceive the actual size of an object
Definition
states that the perceived angular size of the moon is proportional to the perceived angular size of objects around it
Angular size contrast theory
Definition
the angle formed at the eye by rays from the extremities of an object viewed
Visual angle
Definition
the angle between two lines of projection . One of which is the real projection from the object to the actual point of projection
Angle of disparity
How can size-distance scaling explain the Ames Room?
- Observer thinks the room is normal.
- People would be at same distance.
- Person on the left has smaller visual angle (R).
- Due to the perceived distance (D) being the same their perceived size (S) is smaller
True or False:
Objects that do not fall on the horopter fall on corresponding points
False
Objects that do not fall on the horopter fall on noncorresponding points
What are the motion-produced depth perception cues?
Motion parallax
Deletion and accretion
Definition
change in the shape of the lens when we focus on objects at different distances
Accomodation
Define
Perspective convergence
parallel lines appear to come together in the distance
Definition
an idea that the perceiver combines the size of object formed on retina and its distance to perceive the actual size of an object
Size-distance scaling
Definition
an optical illusion which causes the Moon to appear larger near the horizon than it does higher up in the sky
Moon illusion
Define
Texture gradient
is the distortion in size which closer objects have compared to objects farther away
Definition
provide depth information when viewing a scene with one eye
Monocular cues
Define
Visual angle
the angle formed at the eye by rays from the extremities of an object viewed
Define
Binocular disparity
the difference in image location of an object seen by the left and right eyes, resulting from the eyes’ horizontal separation (parallax)
Define
Ponzo illusion
one among a number of illusions where a central aspect of a simple line image—e.g. the length, straightness, or parallelism of lines—appears distorted by other aspects of the image—e.g. other background/foreground lines, or other intersecting shapes
Define
Atmospheric perspective
a technique of rendering depth or distance in painting by modifying the tone or hue and distinctness of objects perceived as receding from the picture plane, especially by reducing distinctive local colors and contrasts of light and dark to a uniform light bluish-gray color
What is size-distance scaling defined by?
Emmert’s law - Perceived size will change depending on distance of projection
Define
Motion parallax
a monocular depth cue in which we view objects that are closer to us as moving faster than objects that are further away from us
Definition
a technique of rendering depth or distance in painting by modifying the tone or hue and distinctness of objects perceived as receding from the picture plane, especially by reducing distinctive local colors and contrasts of light and dark to a uniform light bluish-gray color
Atmospheric perspective
Define
Pictorial cues
any information conveyed to the observer of a two-dimensional image that gives the impression of 3-dimensional image
Definition
the difference in image location of an object seen by the left and right eyes, resulting from the eyes’ horizontal separation (parallax)
Binocular disparity
What are oculomotor cues based on?
Oculomotor cues are based on sensing the position of the eyes and muscle tension
What is the range of effectiveness for atmospheric perspective?
Very far (30+m)
Definition
cell in the visual cortex that receives inputs from both eyes and responds only when the binocular disparity is within certain predetermined limits, thus providing a basis for stereopsis
Disparity-selective cells
Define
Uncrossed disparity
the binocular disparity produced by images that lie beyond the horopter in visual space
List the different monocular/pictorial cues for depth perception
- Occlusion - when one object partially covers another
- Relative height - objects below the horizon that are higher in the field of vision are more distant
- Objects above the horizon lower in the visual field are more distant
- Relative size - when objects are equal size, the closer one will take up more of your visual field
- Perspective convergence - parallel lines appear to come together in the distance
- Familiar size - distance information based on our knowledge of object size
- Atmospheric perspective - distance objects are fuzzy and have a blue tint (on a clear day)
- Texture gradient - equally spaced elements are more closely packed as distance increases
- Shadows - indicate where objects are located – Enhance 3-D of objects
Define
Corresponding retinal points
Two points (or small areas), one in each retina, which when simultaneously stimulated give rise to the perception of a single object. These points share a common line of direction and this explains why stimulating them is perceived as arising from the same point in space
What is the range of effectiveness for motion parallax?
Near to moderately far (0-20m)
Definition
a geometric illusion in which two lines of equal length appear unequal depending on whether angular lines forming arrowheads at each end point toward or away from each other
Muller-Lyer illusion
Definition
a line or surface containing all those points in space of which images fall on corresponding points of the retinas of the two eyes
Horopter
Definition
difference in its angular distance from the fovea in the two eyes
Absolute disparity
Define
Stereopsis
the perception of depth produced by the reception in the brain of visual stimuli from both eyes in combination; binocular vision
Define
Ames room
a distorted room that creates an optical illusion
What does the cue approach to depth perception focus on?
This approach focuses on information in the retinal image that is correlated with depth in the scene.
Definition
is the distortion in size which closer objects have compared to objects farther away
Texture gradient
Definition
a perceptual clue which allows you to determine how close objects are to an object of known size
Relative size
Definition
the phenomenon of items associated to the same cue as the target blocking the successful retrieval of that target, through strength dependent response competition
Occlusion
Definition
the fact that our peceptions of the size of objects are relatively constant despite the fact that the size of objects on the retina vary greatly with distance
Size constancy
What are the two main types of oculomotor cues?
- Ocular Convergence - inward movement of the eyes when we focus on nearby objects
- Accommodation - change in the shape of the lens when we focus on objects at different distances
Definition
the binocular disparity produced by images that lie beyond the horopter in visual space
Uncrossed disparity
Define
Conflicting cues theory
a theory of visual illusions proposed by R. H. Day, which states that our perception of line length depends on an integration of the actual line length and the overall figure length
Definition
proposes that the horizon Moon looks larger than the zenith Moon because it looks farther away
Apparent distance theory
Definition
a monocular depth cue in which we view objects that are closer to us as moving faster than objects that are further away from us
Motion parallax
Definition
parallel lines appear to come together in the distance
Perspective convergence
Define
Ocular convergence
inward movement of the eyes when we focus on nearby objects
Define
Angular size contrast theory
states that the perceived angular size of the moon is proportional to the perceived angular size of objects around it
Define
Size constancy
the fact that our peceptions of the size of objects are relatively constant despite the fact that the size of objects on the retina vary greatly with distance
Definition
neurons in the visual system that assist in the creation of stereopsis from binocular disparity. They receive inputs from both the right and left eyes and integrate the signals together to create a perception of depth
Binocular depth cells
Objects that do not fall on the horopter fall on noncorresponding points, making disparate image. The angle between these points is the _____________
Objects that do not fall on the horopter fall on noncorresponding points, making disparate image. The angle between these points is the absolute disparity
Definition
a visual cue used to judge an object’s distance. It is a monocular cue which means it can provide information about depth peception even by using only one eye
Familiar size
Define
Absolute disparity
difference in its angular distance from the fovea in the two eyes
Define
Angle of disparity
the angle between two lines of projection . One of which is the real projection from the object to the actual point of projection
Define
Moon illusion
an optical illusion which causes the Moon to appear larger near the horizon than it does higher up in the sky
What is the range of effectiveness for occlusion?
Near - very far
Definition
objects below the horizon that are higher in the field of vision are more distant
Relative height
What is the size-distance scaling equation?
S = K(RD)
where K is as constant; R is retinal image size; D is perceived distance
How can relative size explain the Ames Room?
- Perception of size depends on size relative to other objects.
- One woman fills the distance between the top and bottom of the room.
- The other woman only fills part of the distance
- Thus, the woman on the right appears taller
Definition
a device by which two photographs of the same object taken at slightly different angles are viewed together, creating an impression of depth and solidity
Stereoscope
Definition
Two points (or small areas), one in each retina, which when simultaneously stimulated give rise to the perception of a single object. These points share a common line of direction and this explains why stimulating them is perceived as arising from the same point in space
Corresponding retinal points
Define
Deletion
the gradual occlusion of a moving object as it passes behind another object
Define
Apparent distance theory
proposes that the horizon Moon looks larger than the zenith Moon because it looks farther away
Define
Binocular depth cells
neurons in the visual system that assist in the creation of stereopsis from binocular disparity. They receive inputs from both the right and left eyes and integrate the signals together to create a perception of depth
Define
Random-dot stereogram
stereo pair of images of random dots which when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth, with objects appearing to be in front of or behind the display level
Define
Occlusion
the phenomenon of items associated to the same cue as the target blocking the successful retrieval of that target, through strength dependent response competition
