Chapter 5
INFANCY
INFANCY
• Sensation: the detection of sensory
stimulation
• Perception: the interpretation of what is
sensed
THE NEWBORN’S READINESS FOR LIFE
• Newborn Reflexes – involuntary, automatic
response to a stimuli
– Survival – adaptive value, satisfy needs;
• breathing, sucking, swallowing
– Primitive – not as useful, disappear 1st year
• Babinski, swimming, grasping
•
Table 5.1 Major Reflexes in Full-Term Neonates
•
Table 5.1 Major Reflexes in Full-Term Neonates (continued)
THE NEWBORN’S READINESS FOR LIFE
• Infant States: six levels of arousal
– Pass through predictable pattern of states
– 70% of time asleep
• Developmental Change in Infant States
– Overall sleep decreases, duration of
episodes increases
– REM – declines; less need for stimulation
while asleep (Autostimulation theory)
– SIDS – leading cause of infant mortality
•
Table 5.2 Infant States of Arousal
THE NEWBORN’S READINESS FOR LIFE
– Functions and Course of Crying
• State communicating distress
–Developmental changes in crying
»Shrill and nonrhythmic may
indicate brain damage
»Tends to diminish after first 3
months – maturation of brain,
increased responsiveness from
parents
METHODS USED TO STUDY THE INFANT’S
SENSORY/PERCEPTUAL EXPERIENCES
• The Preference Method
– Discriminate between stimuli
• The Habituation Method
– Familiarity leads to a lack of response
– Dishabituation – response to new stimuli
METHODS USED TO STUDY THE INFANT’S
SENSORY/PERCEPTUAL EXPERIENCES
• The Method of Evoked Potentials
– Present a stimulus and record brain waves
• Discrimination of stimuli produces
different brain wave patterns
• The High-Amplitude Sucking Method
– Rate of sucking on a pacifier controls the
presentation of a stimuli, shows preference
and discrimination
•
Figure 5.3 An EEG cap is used to place electrodes around the baby’s head to record electrode
activity at appropriate places on the baby’s brain.
•
Figure 5.4 The high-amplitude sucking apparatus.
INFANT SENSORY CAPABILITIES
• Hearing
– Discriminate sounds based on loudness,
duration, direction, and frequency
– Prefer mother’s voice to other women
– Sensitive to phonemes, even better than
adults (if sounds are not part of the adult’s
spoken language)
– Hearing loss can adversely affect
development (often due to ear infections)
INFANT SENSORY CAPABILITIES
• Taste and Smell
– Prefer sweet over sour, bitter, or salty
– Avoid unpleasant odors
– Recognize mother by smell (if breast-fed)
• Touch, Temperature, and Pain
– Touch enhances development, allows
exploration of environment
– Sensitive to temperature
– Sensitive to pain – even at 1 day
INFANT SENSORY CAPABILITIES
• Vision
– Least mature sense
– Detect changes in brightness
– Can see patterns
– See colors, although discrimination is good
by 2-3 months
– Poor acuity, see as well as adults by 12
months
•
Table 5.3 The Newborn’s Sensory Capabilities
VISUAL PERCEPTION IN INFANCY
• Perception of Patterns and Forms
– Early Pattern Perception (0 to 2 Months)
• Prefer high contrast patterns
• Prefer moderately complex patterns
• Prefer patterns that move
•
Figure 5.5 Fantz’s test of young infants’ pattern preferences. Infants preferred to look at complex
stimuli rather than at a simpler black-and-white oval. However, the infants did not prefer the
facelike figure to the scrambled face. ADAPTED FROM FANTZ, 1961.
•
Figure 5.6 What patterns look like to the young eye. By the time these two checkerboards are
processed by eyes with poor vision, only the checkerboard on the left may have any pattern left to
it. Poor vision in early infancy helps to explain a preference for moderately complex rather than
highly complex stimuli. ADAPTED FROM BANKS & SALAPTEK, 1983.
VISUAL PERCEPTION IN INFANCY
– Later Form Perception (2 months – 1 year)
• More sensitive to movement
• Begin to perceive objects as whole
forms
• Use subjective contours
• Results from interaction between vision,
biological maturation, and learning
•
Figure 5.7 Perceiving objects as wholes. An infant is habituated to a rod partially hidden by the
block in front of it. The rod is either stationary (A) or moving (B). When tested afterward, does the
infant treat the whole rod (C) as “familiar”? We certainly would, for we could readily interpret cues
that tell us that there is one long rod behind the block and would therefore regard the whole rod as
familiar. But if the infant shows more interest in the whole rod (C) than in the two rod segments (D),
he or she has apparently not been able to use available cues to perceive a whole rod. ADAPTED
FROM KELLMAN & SPELKE, 1983.
•
Figure 5.8 By 3 months of age, infants are perceiving subjective contours such as the “square”
shown here. ADAPTED FROM BERTENTHAL, CAMPOS, & HAITH, 1980.
VISUAL PERCEPTION IN INFANCY
• Perception of Three-Dimensional Space
– Size Constancy
• Present at birth, not fully developed until
10 – 11 YEARS old
• Movement cues important (1-3 months)
• Binocular cues important (3-5 months)
– Pictorial Cues (monocular)
• develop by age 6-7 months
•
Figure 5.10 If infants are sensitive to the pictorial cue of interposition, they should reliably reach for
the “closest” area of a visual display (left side in this example). Seven-month-olds show this
reaching preference, whereas 5-month-olds do not. FROM GRANRUD & YONAS, 1984.
VISUAL PERCEPTION IN INFANCY
– Development of Depth Perception
• Use of visual cliff
–Most infants at 6½ months (crawling)
perceived depth
–2 month-olds showed decrease in
heart rate – a sign of interest, but not
fear
–Experience through motor
development is important
•
Figure 5.11 An infant at the edge of the visual cliff.
INTERMODAL PERCEPTION
• Are the Senses Integrated at Birth?
– Yes: reaching for objects that are seen
– Yes: looking in the direction of sounds
– Yes: expecting to see source of sound, or
to feel objects that were reached for
INTERMODAL PERCEPTION
• Development of Intermodal perception
– 1-month-olds show weak oral-to-visual
perception
– 4 months – intermodal matching between
vision and hearing
– 4-6 months – match tactile and visual
sensations
•
Figure 5.12 Mean times for infants to cross the visual cliff as a function of condition.
INTERMODAL PERCEPTION
• Explaining Intermodal Perception
– Intersensory redundancy hypothesis
• Amodal detection of a stimulus aids in
development and differentiation of
individual senses
• At birth – perception is amodal
• Experiencing multimodal stimuli leads to
intermodal perception
CULTURAL INFLUENCES ON INFANT
PERCEPTION
• Language – become sensitive to sounds
important to specific language
– English vs. Chinese and “r” and “l”
• Music – familiar with own culture’s music
– Western major/minor vs. Javanese scale
• Growth of perceptual skills includes adding
new skills and losing unnecessary ones
• Culture determines which sensory inputs are
distinctive and how to interpret those inputs
BASIC LEARNING PROCESSES IN INFANCY
• Learning
– Change in behavior that
• Produces a new way to think about,
perceive, or react to the environment
• Is the result of experience
• Is relatively permanent
BASIC LEARNING PROCESSES IN INFANCY
• Habituation – process by which we stop
responding to a repeated stimulus
• Dishabituation – attending to a new stimulus
– Developmental Trends
• Possible before birth
• 4 months – may take long exposure
• 5-12 months – need a few seconds
• 10-14 months – habituate to objects and
relationships between objects
•
Figure 5.13 Support habituation and test events: Containment test events
•
Figure 5.13 Support habituation and test events: Containment test events (continued)
BASIC LEARNING PROCESSES IN INFANCY
– Individual Differences in Habituation
• Some habituate slowly and forget rapidly
• Others habituate rapidly and forget
slowly
–Rapid habituation between 6-8
months
»Better language skills in 2nd year
»Higher IQ later in childhood
BASIC LEARNING PROCESSES IN INFANCY
• Classical Conditioning
– Unconditioned stimulus (UCS) elicits an
unconditioned response (UCR)
– Neutral conditioned stimulus (CS) paired
with (UCS)
– Eventually CS elicits a conditioned
response (CR)
– Possible for newborns, but must have
survival value
BASIC LEARNING PROCESSES IN INFANCY
• Operant Conditioning
– Learner emits a response (operates on
environment)
– Associates this action with the
consequences it produces
• Repeat favorable, limit unfavorable
– Newborns learn very slowly, rate increases
with age
– At 2 months, memory is context-dependent
•
Figure 5.14 Basic principles of operant conditioning.
•
Figure 5.15 When ribbons are attached to their ankles, 2- to 3-month-old infants soon learn to
make a mobile move by kicking their legs. But do they remember how to make the mobile move
when tested days or weeks after the original learning? These are the questions that Rovee-Collier
has explored in her fascinating research on infant memory.
BASIC LEARNING PROCESSES IN INFANCY
• Observational Learning –
– Attend to a model and form a symbolic
representation of model’s behavior
• Newborn imitation – possible at 7 days
old, if part of behavioral repertoire
• Imitation of novel responses – reliable
between 8-12 months old
• Immediate imitation at first, deferred
imitation later
•
Figure 5.16 Sample photographs from videotaped recordings of 2- and 3-week old infants imitating
tongue protrusion, mouth opening, and lip protrusion.