I. What do we study?

A. theoretical approaches

1. constructivist: perception is learned

2. direct perception: perception is prewired

a. Gibsons proposed that action and perception are tied
  1. anticipate the movement of a rolling ball

2. ventral (to temporal lobe) vs. dorsal (to parietal-motor strip) visual system
 

a. recognition vs. action

b. dorsal functions earlier

B. tasks

1. attending

2. identifying

3. locating

C. systems

1. visual and auditory

A. methods

1. preferential looking

2. habituation

3. operant conditioning

A. attention getting vs. attention holding stimuli

B. orienting reflex

1. anenchephalics @ 1 month = normal @ 2 mos.

C. overt and covert deployment of attention 1. Johnson et al.
  a. 4 mo-olds could covertly attend to a stimulus (operant conditioning) D. visual scanning 1. edges to interiors

2. is correlated with a shift from sub- to cortical processing

E. stimulus complexity

1. preference for moderate stimulation

a. sleep as a moderator for infants

2. preference for moderate complexity

a. moderate-discrepancy hypothesis

1. checkerboards - 3 wks: 2X2, 14 wks: 8X8

2. familiarity - prefer 24X24 patterns @ 4 mos

F. expectations

A. visual acuity

1. 20/660, 20/300 @ 2 mos., 20/160 @ 4 mos., 20/80 @ 8 mos.

2. greatest sensitivity at low spatial frequencies

B. visual tracking

1. jerky at birth - at 4 mos. smooth movement for slow items

2. attention to motion -> object properties

a. at 3 mos., independent movement = separate objects

C. color

1. evidence that 1 mo olds can discriminate across the spectrum

2. perception, but no preference until about 6 mos

D. face perception

1. preference for faces early on

a. faces special at 3 mos

b. tendency to track moving faces declines btn 4-6 weeks

1. subcortical attentional processes

2. distinctions among faces

a. newborns prefer mother’s face

b. attractive faces as young as 2 - 3 months

1. fit prototype

2. biological predisposition

A. monocular cues to depth

1. motion cues: visual expansion, motion parallax, occlusion

2. pictorial cues: relative size, texture, interposition at 6-7 mos

B. binocular cues to depth - stereopsis

1. emerges suddenly @ 4 mos

2. maturation & visual experience before the age of 3

C. using depth cues

1. the visual cliff

a. 7 month olds: crawlers (6-8 wks) show fear

b. self-generated locomotion is key

1. occurs with walker training, too

A. attending

1. auditory abilities even before birth

2. most interested in sounds in the speech range

a. by 4 mos a preference for one’s own name!

B. identifying

1. speech

a. categorical perception of speech sounds

b. loss of sensitivity to other language sounds @ 10 mos

1. continues to 8 years

2. by 9 mos, a preference for listening to own language sounds

c. discriminating voices
 

1. @ 3 days, a preference for mother’s voice

2. prenatal exposure?

3. preference for motherese by 2 days old

2. music

a. some categorical perception

1. plucks vs. bows @ 2 mos, but not rise time

b. lateralization

1. 4-6 wks premature for speech

2. 2 mos for music

C. locating 1. auditory localization
  a. newborns better than 2 and 3 month olds, but not 4 month olds
  1. back to subcortical functioning!

b. improves gradually from 2 mos to 1.5 years

A. attending

a. 5 - 7 months scanning of faces when a voice is heard

B. identifying

a. evidence for the integration of tactile & visual @4 mos.

1. equal skill for blind and sighted kids

b. integration of sound and movement

C. locating

a. @ 3 mos - reach in the dark & light

b. sonar aids for blind children