Development Flashcards
Preferential looking technique
Determining infant visual attention by presenting 2 stimuli and tracking eye movement; experimenter is blinded to images
Habituation method
1 stimulus presented repeatedly until infant loses interest (habituation); new stimulus presented; if rehabituation occurs, infant can discriminate between them
Visual evoked potential
Electrode placed over V1 measures neural responses to visual stimulus
Describe visual accuity development (3)
Poor at birth - 20/400 to 20/600 at 1 month
Rapid increase from 6-9 months
Full accuity reached at 1 year age
Reasons for poor visual accuity at birth (2)
Visual cortex not fully developed
Shape and size of cones not fully developed
Differences between newborn cone and adult cone (2)
Newborn - short, fat inner segment; short, thin outer segment
Adult - long, thin inner segment; long, thin outer segment; fovea more densely populated
Spatial frequency
Number of cycles per degree of visual angle
Describe infant contrast sensitivity (3)
Infants can perceive contrast at only low frequencies; at low frequencies many times lower than adults; can see little or nothing beyond 2-3 cycles per degree, which is adults’ most sensitive range
Depth perception study (Fox et al.)
Used random dot sterograms (patterns with a region that’s shifted in one eye); infants view pattern through stereoscope, shifted region appears to be shifted in depth; can’t see shifted region without binocularly combining images; measure whether infant follows moving 3D pattern; ability to use stereopsis evident (infants used binocular disparity to view moving 3D object image); limitation: eye-tracking may not be due to stereopsis, rather cue of movement of image
Describe development of depth perception (3)
Stereopsis appears at 3-4 months, crude
Gets better - at 2-3 years have fairly good binocular disparity
Adult levels reached ~12 years
Binocular disparity study (Aslan)
Recorded infant eye movements between two objects at different distances; convergence and divergence observed in 1-2 month old infants, not reliable; 3-4 month fixation reliable
Depth perception study (Held)
6-9-month-old infants; modified version of Fox et al. study, did not use moving image, rather preferential looking technique (controlled for cue of movement); better methodology
Visual cliff study results (Gibson & Walk)
Explanation
6 months - would crawl across the deep side
8 months - would not
3 months - when placed on cliff side, observed widening of eyes and increase in heart rate
Depth perception present at 6 months but no understanding of concequences of falling
Familiar size study results (Granrud et al.)
Explanation
7 months - reached for object
5 months - did not
Used familiar size to interpret bigger object as now being closer
Pictorial cues (4)
Overlap, perspective, texture gradients, familiar size
Development of face perception found from simulated study (4)
Infant - poor but develops rapidly in first year, can still see some features
8 weeks - easy to identify face
3-4 months - can distinguish between face emotions and cats vs dogs
6 months - acuity near adult levels
Perceiving faces study (Morton & Johnson)
Stimuli presented to newborns hour after birth; infants paid more attention to moving face vs other face-like stimuli
Why does face perception not reach full levels until adolescence?
Smaller FFA in 8-year-olds
Preference for faces (Turati et al.) results
1-4-day-olds look longer at displays with more elements in top half
No preference for face-like images
Perceiving object unity study (Kellman and Spelke)
Tested 4-month-old infants; rod behind block, two conditions - moving and not moving rod; dishabituation occured for disjointed rod in movement condition, indicating inference of continuity made through movement behind block
Newborn hearing (Olsho et al.) study
Presented sounds to newborns and older infants, tracked head movements; newborns turned head to sounds location
3-month-olds - audibility curve similar shape to adults, shifted upwards
6-month-olds - audibility curve similar to adults within 10-15 dB
Preference for mother’s voice study (DeCasper and Fifer) results
2-day-olds showed preference for mother’s voice over stranger’s by adjusting sucking pattern; other studies show preference for native language
Perceiving speech study (Eimas et al.) results
1-month-olds exposed to phonemes of different VOTs; dishabituation occurs when VOT crosses phonetic boundary; no change for simuli on same side of phonetic boundary or for unchanging stimulus
Development of phoneme perception (2)
Birth - can distinguish between phonemes of all human languages
1 year - only phonemes of native language can be distinguished
Tactile and visual perception study (Kaye and Bower) results
1-day-olds modified sucking behaviour to view image of pacifier they were sucking
Intermodal sound and vision perception study (Kuhl & Meltzoff) results
4-month-olds matched face to phoneme produced by paying more attention to correct face (74% of time)
Intermodal perception of mother study on brand-newborns (Sai) results
Newborns showed preference for mother’s face when they had heard her talk before testing, linking her voice to her face
Newborns who had not heard their mother’s face prior to testing showed no preference for mother’s face
Development of olfaction and taste
Newborns react to a number of olfactory stimuli
No responses to salty stimuli, which develops later
Paired comparsion method
Stimulus is presented during familiarization period; then paired with novel stimulus (recognition period); if newborn pays more attention to novel stimulus, discrimination evident
Paired comparison study (Pascalis et al.) results
All ages show recognition of novel human face; only 6-month-olds can discriminate between primate faces; 9-month-olds can not
PLT perceiving mother’s face study
Preferential looking technique - 2-day-olds prefer mother’s face 63% of the time
Perceiving object unity (Johnson et al.) study
Newborns did not prefer disjointed rod after habituation; 3-month-olds can be perceivers or nonperceivers
