Quiz 4

How movement contributes to perception?

By interpreting perception and action based on survival, attentional capture, and shape and event perception

What or Perception pathway

Visual cortex; ventral stream: Identifies and consciously perceives objects

Where or How or Action pathway

Visual cortex to parietal lobe; dorsal stream: Locates objects and guides physical interaction with them

Mirror neuros

Located in the premotor cortex. They activate after perceiving an action performed by others, enabling understanding and imitation of those actions. *Diminished activation if the action is performed with tools in monkeys

Motion Perception

Real motion, biological motion, implied motion, and representational momentum

Real motion

An object physically changes position over time

Evidence for real motion

Actual displacement produces motion information

Biological motion

Movement of a person or other living organism

Evidence for biological motion

Point-light walkers reveal living movement from a few moving lights

Implied motion

A still picture depicts an action involving motion

Evidence for implied motion

Motion-sensitive Middle Temporal (MT) and Middle Superior Temporal (MST) areas respond even through the image is stationary

Grossman and Black

Point-light walker experiment where they compared scrambled point-light motion to biological motion patterns, resulting in structure-from-motion observed in the Superior Temporal Sulcus (STS)

Structure-from-motion

Occurs when moving-light points allow the observer to perceive an organized body

Kourtzi and Kanwisher

Measured responses in motion areas MT and MST by comparing implied-motion vs. no-implied-motion pictures. They found motion systems can respond to represented motion even without real physical movement

Depth perception cues

properties of the retinal image state that correlate with distance. Repeated exposure makes many cue-depth associations automatic

Types of depth perception cue classes

Oculomotor, monocular pictorial, motion-produced, and binocular

Oculomotor cues

Convergence and accommodation

Monocular pictorial

Occlusion, relative height, relative size, perspective convergence, familiar size, atmospheric perspective, texture gradient, and shadows

Motion-produced cues

Motion parallax and deletion and accretion

Binocular cues

Binocular disparity and stereopsis

Physiology and development of binocular depth

Disparity-selective or binocular-depth cells respond best to particular degrees of disparity between the two retinal images

Blake and Hirsch

Coordinated early input from both eyes is important for normal binocular depth perception. They alternated visual input between the two eyes of developing cats. As a result, the cats developed few binocular neurons and could not use binocular disparity normally.

Holway and Boring

Perceived size depends on perceived distance as well as retinal size. They conducted experiments showing that observers misjudged the size of objects when distance cues were manipulated.

Size constancy and scaling