Perceptual Organization

• Gestalt - an organized whole

  • Gestalt psychologists emphasized our tendency to integrate pieces of information into meaningful wholes

  • Example: you need both eyes to have seamless vision

  • Example: Necker Cube - you see a cube in the blue circles, even where there isn’t one

• In perception, the whole may exceed the sum of its parts

• Our brain does morethan register information about the world

Form Perception

• Figure and Ground

  • Figure-ground - the organization of the visual field in objects (figures) that stand out from their surroundings (ground)

• Grouping

  • The perceptual tendency to organize stimuli into coherent groups

  • Rules

    • Proximity: grouping nearby figures together

    • Continuity: perceiving smooth, continuous figures, rather than discontinuous ones

    • Closure: filling in gaps to create a complete, whole object

Depth Perception

• The ability to see objects in three dimensions although the images that strike the retina are two-dimensional

  • Allows us to judge distance

  • Eleanor Gibson baby example

  • Visual cliff - a laboratory device for testing depth perception in infants and young animals

• Binocular Cues

  • A depth cue, such as retinal disparity, that depends on the use of two eyes

  • Used to judge the distance of nearby objects

  • Convergence - the inward angle of the eyes focusing on a near object

  • Retinal disparity - a binocular cue for perceiving depth

    • By comparing images from two eyes, the brain computes distance - the greater the disparity between the two images, the closer the object

• Monocular Cues

  • A depth cue, such as interposition or linear perspective, available to either eye alone

  • Relative height - we perceive objects higher in our field of vision as farther away

  • Relative motion - as we move, objects that are actually stable may appear to move

    • NOOOOOOOOOO

  • Relative size - if we assume two objects are similar in size, most people perceive the one that casts the smaller retinal image as farther away

  • Linear perspective - parallel line appear to meet in the distance; the sharper the angle of convergence,the greater the perceived distance

  • Interposition - if one object partially blocks the view of another, it is perceived as closer

  • Light and shadow - shading produces a sense of depth consistent with our assumption that light comes from above

Motion Perception

• Stroboscopic movement - perceiving rapid series of slightly varying images as a continuous movement

• Phi phenomenon - an illusion of movement created when two or more adjacent lights blink on and off in quick succession

Perceptual Consistency

• Perceiving objects as unchanging, even as illumination and retina images change

• Color and Brightness Constancies

  • Color constancy - perceiving familiar objects as having a consistent color, even if changing illumination alters the wavelengths, reflected by the object

  • Ex: blue/black vs white/gold dress

  • Color is seen relative to the objects surrounding a certain object

  • Brightness constancy -  the amount of light an object reflects relative to its surrounding stays constant

• Shape and Size Constancies

  • Shape constancy - the form of familiar objects stay constant while retinas receive rapidly changing images of them

  • Size constancy - an object has an unchanging size, even while distance from it varies

  • Moon illusion - the moon looks up to 50 percent larger when near the horizon than when high in the sky

• Our brain constructs our perceptions.

Perceptual Interpretation

• Restored Vision and Sensory Restriction

  • If a man born blind who was taught by touch to distinguish between a cube and sphere, could not distinguish the two through sight

  • Children who have cataracts move may never be normal visually

  • Critical period - optimal period during childhood when exposure to certain stimuli or experiences is required

• Perceptual Adaptation

  • The ability to adjust to changed sensory input, including an artificially displaced or even inverted visual field