Psychology 350
Lecture 6
9-25-00
Outline
Perceptual abilities of neonates
Developmental themes
Methods to study infants’ perception
Well-Developed Sensory Abilities of Neonates
Skin senses - Proprioception
Body orientation - Vestibular system
Taste & Smell - Chemical sensitivity
Auditory Perception of Infants
Discriminates mother’s voice first week
Prefers female voices, rhythmic sounds about 5-15 seconds long
Discriminates speech categories, exp. pa vs ba
Visual Perception of Infants
Brightness
Orienting reflex
Fixation, focus, acuity
Tracking
Scanning
Color vision
Size & shape constancy
Depth perception
Two Perceptual Processes
Attention-drawing features of stimuli such as loud noises, contours, bright colors stay constant during development and are mediated by subcortical processes
Attention-holding features of stimuli change developmentally and are mediated by cortical processes
Perceptual Development Themes
Biological preparedness
Recognition of familiarity
Attention to novelty
Integration of sensory information
Questions About Infant Perception
Why is it so difficult to study infants?
Do infants perceive haphazard bits of stimuli or organized information?
How quickly do infants’ perceptual abilities develop?
Methods to Study Infant Perception
Looking Preferences
Fantz - watch retinal reflections
Cameras record retinal images
Spelke - intermodal matching: look at matching stimuli
Wynn - differential looking times
Methods to Study Infant Perception
Visual Scanning
1 month old babies scan contours and high contrasts
2-3 month old babies scan interior of faces and look at eyes and mouth, especially during sustained attention
Methods to Study Infant Perception
Differential Sucking Rates
2-3 month olds learn to suck at a rate to keep movie in focus
3 month olds suck more on novel objects than familiar ones (shows exploration)
Methods to Study Infant Perception
Heart Rate Changes
Deceleration indicates orientation and interest
Acceleration indicates alarm or fear
Lansink & Richards (1997) CD
Investigated link between heart rate and behavioral ratings of infant attention
Hypothesis: When infants have heart rate deceleration, they are in sustained attention and most resistant to distraction
Design: Cross-sectional
Ss: 56 infants at 6, 9, and 12 months
Method: Infants sat on parents’ laps and played with toys attached to table
Conditions: Presented distractors when infants had focused or casual attention and heart rate acceleration or deceleration
Dependent variable: Latency to look at TV
Result: Distraction latency longest during heart rate deceleration and focused attention
Conclude: Heart rate is good measure of attention and information processing
Methods to Study Infant Perception
Habituation & Dishabituation
Changes in responses to familiar or novel stimuli
Responses can be heart rate, looking times,or sucking rate
Exps. of categorical speech perception, discrimination between small quantities, unitary objects, expectancies
Conclusions
Many perceptual abilities are innate
Perceptual abilities are quickly modified and integrated
Infants perceive cognitive invariants of shape, size, color, unity, small number
Perceptual organization supports cognitive and social development during infancy