chapter 10 (S&P)

• cue approach to depth perception focuses on what?

  focuses on identifying information in the retinal image that is correlated with depth in the scene
• occlusion

  a cue that one object is in front of another Example: perceiving a cat behind a fence (left) or when an object is seen as being partially further away than another object
• oculomotor


  cues based on our ability to sense the position of our eyes and tension in our eye muscles
• monocular


  cues based on the visual information available within one eye
• binocular


  cues that depend on visual information within both eyes
• What are oculomotor cues created by?

  convergence and accommodation
• convergence


  the inward movement of the eye that occurs when we look at nearby objects
• accommodation


  the change in the shape of the lens that occurs when we focus on objects at various distances
• convergence and accommodation indicates when an object is _____?

  close; both are useful up to about a distance of arm's length
• which of the two is more effective? Convergence or accommodation?

  convergence
• pictorial cues


  sources of depth information that can be depicted in a picture, such as the illustrations in this book(textbook) or an image on the retina
• movement-based cues


  sources of depth information created by movement
• relative height


  objects with their bases closer to the horizon are usually seen as being more distant i.e. this means that being higher in the field of view causes objects on the ground to appear farther away whereas being lower in the field of view cause objects in the sky to appear farther away
• familiar size


  judging distance based on our prior knowledge of the size of objects
• what experiment that William Epstein propose?

  he created an experiment that shows that under certain conditions, our knowledge of an object's size influences our perception of that objects distance
• relative size 


  when objects are equal size, the

  closer one will take up more of your visual field

  (Larger Retinal Angle)
• perspective convergence


  parallel lines appear to come together in the distance.

  
  

  example: when you look down parallel railroad tracks
• what cue was often sed by Renaissance artists to add to the impression of depth in they paintings, as in Pietro Perugino's?

  relative size
• atmospheric perspective


  the acquired ability to differentiate near and distant objects on the basis of their clear or indistinct appearance
• what are the two motion-produced cues?

  motion parallax and deletion and accretion
• texture gradient


  when a number of similar objects are equally spaced throughout a scene
• motion parallax


  close objects glide rapidly past but objects in the distance appear to move slowly.

  
  

  example: nearly objects appearing to speed by in a blur when in a moving car whereas objects that are farther away may appear to be moving only slightly
• stereoscopic vision


  perception of the shape, depth, and distance of an object as a result of having binocular vision

  example: the position of your front finger changing relative to the rear finger after closing your right eye and then left eye
• stereoscopic depth perception


  depth perception created by input from both eye
• what is the story about Susan Barry about

  a neuroscientist whose had eye problems since childhood where she was cross-eyed, so when she looked at something with one eye, the other eye would be looking somewhere else
• strabismus


  disorder in which the eyes don't look in exactly the same direction at the same time
• binocular disparity


  difference in images from two eyes
• corresponding retinal points


  points on the retina that would overlap if the eyes were superimposed on each other
• non corresponding points


  two points, one on each retina, that would not overlap if the retinas were slid onto each other

  
  

  example: because Bill is not on the horopter, his image falls on non corresponding points
• absolute disparity


  the degree to which an image deviates from falling on corresponding points
• angle of disparity


  the visual angle between the images of an object on the two retinas
• crossed disparity 


  the pattern of disparity where the LEFT eye sees an object to the right of the observers fixation point and RIGHT eyes sees the same object to the left of the fixation point
• when does crossed disparity occurs?


  it occurs whenever an object is closer to the observer than where the observer is looking
• uncrossed disparity


  when the LEFT eye sees an object to the left of the observers fixation point and the RIGHT eyes sees the same object to the right of the fixation point
• relative disparity


  the difference between the absolute

  disparity of two objects.
• stereopsis


  depth information provided by binocular disparity
• What did Bela Julesz create?

  Bela created a stimulus called the random-dot stereogram, which contains no pictorial cues
• random-dot stereogram


  two identical random-dot patterns that were created on a computer first, followed by the shifting of a square-shaped section of the dots one or more units to the side
• stereoscope


  a device that uses two lenses to focus on the left image on the left eyes and the right image on the right eye
• disparity selective cells


  neurons that signal different amounts of disparity

  
  

  were discovered when research in the 1960s and 1970s revealed neuron that respond to disparity in the primary visual cortex, area vi