AP Psychology: Perception

Perception

The processor of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Figure-ground Relationship

Our ability to perceive any object (the figure) as distinct from its surroundings (the ground).

Visual Capture

The tendency for vision to dominate the other senses when conflicting information is being received

Gestalt Organization Principles

Gestalt psychologists emphasize our tendency to integrate individual pieces of information into a meaningful whole. To bring order and form to basic visual sensations, our brains follow certain rules for grouping stimuli together.

• Proximity: We group nearby objects as belonging together

• Similarity: Figures similar to each other (i.e, as in shape or color) are grouped together.

• Continuity: we perceive smooth, continuous patterns rather than discontinuous ones

• Closure: We fill in gaps to create complete, whole objects

• Connectedness: When uniform and linked, we perceive spots, lines, or areas as single units

Proximity, Similarity, Continuity, Connectedness, Closure

Gestalt Organizational Principles

Proximity

Gestalt Organizational Principle:

We group nearby objects as belonging together

Similarity

Gestalt Organizational Principle:

Figures similar to each other (i.e. as in shape or color) are grouped together

Continuity

Gestalt Organizational Principle:

We perceive smooth, continuous patterns rather than discontinuous ones.

Connectedness

Gestalt Organizational Principle:

When uniform and linked, we perceive spots, lines, or areas as single units

Closure

Gestalt Organizational Principle:

We fill in gaps to create complete, whole objects

Visual Cliff

A laboratory device for testing depth perception in infants. Even when coaxed, infants are reluctant to venture into the glass over the cliff.

Binocular Cues

Depth cues that depend on the use of both of our eyes:

• Retinal Disparity

• Convergence

Retinal Disparity

By comparing the two slightly different images received on each retina, the brain computes the distance of what we are looking at. The greater the disparity (difference) between the two images, the closer the object.

Convergence

The extent to which the eyes converge inward when looking at an object. The greater the convergence, the closer the object.

Retinal Disparity and Convergence

The 2 Binocular Cues

Monocular Cues

Distance cues that require the use of one eye only.

Relative size, interposition, relative clarity, texture gradient, relative height, linear perspective, light and shadow, relative motion

Monocular Cues (8 of them)

Relative Size

Monocular cue:

If we assume two objects are about the same size, the one that casts the smaller retinal image is perceived as being farther away.

Interposition (Overlap)

Monocular cue:

If one object partially blocks another, the one that is partially blocked is perceived to be farther away

Relative Clarity

Monocular cue:

Because light from distant objects must pass through more atmosphere, we perceive hazy objects as being farther away than clear, distinct objects.

Texture Gradient

Monocular cue:

A gradual change from a coarse, distinct texture into a fine, indistinct texture signals increasing distance

Relative Height

Monocular cue:

We perceive objects higher in our visual field as being further away

Linear Perspective

Monocular cue:

Parallel lines (such as railroad tracks) appear further away as they converge in the distance

Light and Shadow (Relative Brightness)

Monocular cue:

Nearby objects reflect more light. Thus, given two identical objects, the dimmer one seems further away.

Relative Motion (Motion Parallax)

If while riding in a train you fix your gaze on some object (the fixation point), objects closer than the fixation point appear to be moving backward. The nearer an object is, the faster it seems to move. Objects behind the fixation point appear to be moving with you. The farther away the object is from the fixation point, the more slowly it appears to move.

Motion Perception

One way we perceive motion is by knowing that if an object keeps getting bigger, it is probably moving towards us. If an object is shrinking, it is moving away from us.

Phi Phenomenon

When two or more adjacent stationary lights blink on and off in quick succession, we perceive a single light moving (lighted signs use this phenomenon)

Stroboscopic Movement

The brain will interpret a rapid series of slightly varying images as continuous movement. By flashing 24 still pictures each second, a motion picture creates perceived movement.

• Like animation

Perceptual Constancies

PErceiving objects as unchanging (having constant lightness, color, shape, and size) even when our retinal images of them change:

• Shape constancy

• Size Constancy

• Lightness Constancy

Shape Constancy

We perceive the form of familiar objects as constant even when our retinal images of them change

Size Constancy

We perceive familiar objects to maintain a constant size even when their distance from us changes.

Lightness Constancy

We perceive an object as having a constant lightness even when its illumination varies.

Sensory Deprivation

People blind from birth, who later have their vision restored, can distinguish figure-ground relationships, can sense color, but have great difficulty recognizing objects that they were familiar with by touch

Perceptual Adaptation

In vision, the ability to adjust to an artificially displaced or even inverted visual field

Perceptual Set

A mental predisposition to perceive one thing and not another (e.g., seeing the Lock Ness Monster instead of a piece of driftwood because of your beliefs)

Context Effects

Any given stimulus may trigger radically different perceptions depending on the surrounding environments or circumstances. Culture may have a great impact on context and perception.

Human Factors Psychology

A branch of psychology that explores how people and machines interact and how machines and physical environments can be adapted to human behaviors