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Infant Capacities and the Process of Change The Development of Children (5 th ed. ) Cole, Cole & Lightfoot Chapter 4
What does this mean? “Babies control and bring up their families as much as they are controlled by them; in fact, we may say that the family brings up a baby by being brought up by him. ” Erikson in Childhood and Society
Why is the case? Compared with many animals that are able to negotiate their environments at birth almost as well as their parents, human beings are born in a state of marked immaturity…. For many years, human offspring must depend on their parents and other adults for their survival. ” Cole, Cole & Lightfoot, p. 114
Overview of the Journey l Brain development l Earliest capacities l Coordination with the social world l Mechanisms of development l First postnatal BSB shift
Brain Development Neurons and Neural Networks Experience and Development The CNS and the Brain
At birth, the brain has all the cells it will have, yet it is ¼ the size of an adult brain. Why? 1. Dendrite size and branching 2. Axon branching and myelination (speed)
Neural Networks in Postnatal Life
Experience and Development Exuberant synaptogenesis Synaptic pruning
Rats Raised in Enriched Environments l l l Increased rates of learning in standard laboratory tasks, such as learning a maze Increased overall weight of the cerebral cortex (the part of the brain that integrates sensory information) Increased amounts of acetylcholinesterase, a brain enzyme that enhances learning Larger neuronal cell bodies and glial cells (which provide insulation, support and nutrients to neuronal cells) More synaptic connections Rosenzweig, 1984
Active Interaction with the Environment l l l Rats were raised with an enriched environment but were housed singly in small cages so that could do no more than observe what was going on around them The learning capacity of these rats differed in no way from that of the animals that were housed in individual cages away from the enriched environment What might this imply for child-rearing? For teaching?
Brain Elements and Functions
Six Mammalian Species Why the difference?
Cortex Development l l Matures later than the lower-lying areas of the CNS, spinal cord, brain stem Primary motor area l l Primary sensory areas l l l First area of the cortex to develop Responsible for voluntary (nonreflexive) movement Begins with raising head (1 month), control of arms and trunk (3 months); leg control is last to develop Begins with touch, then visual, then auditory By 3 months, all primary sensory areas are relatively mature Frontal cortex (e. g. , planning, decision-making) l Begins to function in infancy but continues to develop throughout childhood
Earliest Capacities Sensory Processes Response Processes
Sensory Processes l l Normal full-term newborns enter the world with all sensory systems functioning, but not all of these systems have developed to the same level due to different developmental rates (i. e. , heterochrony) Indications of sensation l l l Turning of the head, variation in brain waves, changes in rate of sucking on a nipple Habituation: Becomes bored and stops attending Dishabituation: Interest is renewed after the infant perceives a change in the stimulus
Hearing l l Infants only minutes old will startle with a loud noise and may even cry Will also turn their heads toward the source of a noise
Hearing l Infants can distinguish the sound of the human voice from other kinds of sounds, and seem to prefer it l l Are particularly interested in speech with the high pitch and slow, exaggerated pronunciation (i. e. , “baby talk”) Evidence that by 2 days old, some babies would rather hear the language that has been spoken around them than a foreign language
Hearing Capacity At 2 months of age: l Present phoneme (e. g. , /pa/) l Habituate (i. e. , return to baseline sucking rate) l New phoneme (e. b. , /ba/) l Dishabituate (i. e. , sucking rate increases)
New Consonant l l Both groups hear a consonant sound Habituate Experimental group hears a new consonant sound at time marked 0 Infants are able to distinguish consonant sounds
Auditory Discrimination and Culture Infants can distinguish among language sounds that do not occur in their native language, but this capacity diminishes during the first year of life.
Infants’ Visual Capacity Based on studies of infant eye movement when a striped visual field passes in front of the eyes, it is evident that visual capacity increases dramatically over the first few months of life.
Fantz Looking Chamber (1960 s) l l Demonstrated that babies less than 2 days old can distinguish among visual forms Tend, however, to focus on areas of high contrast, such as lines and angles
Development of Visual Scanning Due to brain maturation
Perception of Faces l l Infants show a preference for patterned stimuli over plain stimuli Babies as young as 9 minutes old will look longer at a schematic moving face than a scrambled one
Visual Preferences of Infants
Expressions of Various Tastes (a) Neutral stimulus (water) (b) Sweet stimulus (c) Sour stimulus (d) Bitter stimulus
Early Sensory Capacities Sense Capacity Hearing Ability to distinguish phonemes Preference for native language Vision Slightly blurred at birth Color vision by 2 months Distinguish patterned stimuli from plain Preference for facelike stimuli Smell Ability to differentiate odors well at birth Taste Ability to differentiate tastes well at birth Touch Response to touch at birth Temperature Sensitivity to temperature changes at birth Position Sensitivity to changes in position at birth
Response Processes l Reflexes l l Emotions l l Automatic (involuntary) responses to specific types of stimulation… Two basic emotions, contentment (+) & distress (-), split into primary emotions (e. g. , joy, anger, fear) at 3 -6 months… Temperament l Individual modes of responding to the environment that appear to be consistent across situations and stable over time…
Reflexes Present at Birth Reflex Description Babinski When the bottom of the baby’s foot is stroked, the toes fan out and then curl Crawling When the baby is placed on his stomach and pressure is applied to the soles of his feet, his arms and legs move rhythmically Moro If the baby is allowed to drop unexpectedly while being held or if there is a loud noise, she will throw her arms outward while arching her back and then bring her arms together as if grasping something Rooting The baby turns his head and opens his mouth when he is touched on the cheek Sucking The baby sucks when something is put in her mouth
Grasping Reflex l l When a finger or some other object is pressed against the baby’s palm, the baby’s fingers close around it Disappears in 3 -4 months; replaced by voluntary grasping
Stepping Reflex l l When the baby is held upright over a flat surface, he makes rhythmic leg movements Disappears in first 2 months, but can be reinstated in special contexts (e. g. , when partially submerged in water)
Infant Expression of Emotions Joy Anger Sadness Disgust Distress Interest Fear Surprise
Infant Expression of Emotions Joy Anger Sadness Disgust Distress Interest Fear Surprise
Temperaments l Three broad categories l l Easy babies: Playful, regular in their biological functions, adapt readily to new circumstances Difficult babies: Irritable, irregular in their biological functions, often respond intensely and negatively to new situations or try to withdraw from them Slow-to-warm-up babies: Low in activity level, responses are typically mild, tend to withdraw from new situations, require more time than easy babies to adapt to change Moderate temperamental stability over first 8 years of childhood l Impact of both genetic and environmental components
Coordination with the Social World Sleeping Feeding Crying
Sleep Patterns in Infants NREM Sleep During first 2 -3 months of life, infants begin their sleep with active (REM) sleep and then fall into quiet (NREM) sleep. Subsequently, the sequence reverses and shifts toward the adult pattern.
Pattern of Sleep/Wake Cycles Newborns sleep ~16½ hours /day, but the longest period of sleep is only 3 -4 hours.
Feeding l When fed “on demand”, majority of newborns preferred a 3 -hour schedule l Interval gradually increased to 4 -hour schedule by 2 ½ months l By 7 or 8 months, 4 x/day
Nursing Behavior Early feeding attempts are rather uncoordinated Infant’s nostrils are blocked while he/she is attempting to feed This elicits a head-withdrawal reflex that interferes with feeding Later attempts become much more coordinated resulting in nursing – an evidence of learning.
Crying l Increases from birth to about 6 weeks and then starts to decrease l At a few months of age, infants begin to cry voluntarily (“crying on purpose”) as the cerebral cortex becomes involved l Crying helped by nursing, holding baby to shoulder, rocking, patting, cuddling, swaddling (reduces overstimulation from uncontrolled limb movements)
Mechanisms of Developmental Change Biological-Maturation Perspective Environmental-Learning Perspective Constructivist Perspective Cultural-Context Perspective
Mechanisms of Developmental Change Biological-Maturation Perspective
Reflex Coordination l l Early, simple reflexes arise from the brain stem More complex, coordinated reflexes result from the maturation of the cerebral cortex
Early Attention to Human Speech In 1 -month-old baby born without a cerebral cortex l On first exposure to sound of human speech, there is a marked decrease in heart rate, indicating attention l After 5 additional presentations of the sound, the infant has habituated
Mechanisms of Developmental Change Environmental-Learning Perspective
Classical Conditioning (a) (b) (c) (d) Sight of a light (CS) elicits no particular response Loud sound of gong (UCS) causes baby to blink (UCR) Sight of light (CS) is paired with sound of gong (UCS), which evokes an eyeblink (UCR) Sight of light (CD) is sufficient to cause the baby to blink (CR), evidence that
Operant Conditioning l l An organism will tend to repeat behaviors that lead to rewards and will tend to give up behaviors that fail to produce rewards or lead to punishment Requirement: Behavior must occur before it can be reinforced
Operant Conditioning l l After only 25 occasions on which the head turning was reinforced with the pacifier, most of the babies had tripled the rate at which they turned their heads. Conversely, those infants who were rewarded with a pacifier for holding their heads still, learned to move their heads less during the course of the experiment.
Mechanisms of Developmental Change Constructivist Perspective (Piaget)
Piaget’s Theory of Developmental Change via Schemas Accommodation Assimilation (Modification of a prior schema) (Incorporated into an existing schema) Equilibration Leads to developmental stages…
Piaget’s Stages of Cognitive Development Age (Yrs) Stage Description Birth – 2 Sensorimotor Achievements consist largely of coordinating sensory perceptions and simple motor behaviors. Come to recognize the existence of a world outside themselves and begin to interact with it in deliberate ways. 2– 6 Preoperational Can use symbols, including mental images, words, and gestures. Often fail to distinguish their point of view from that of others, become easily captured by surface appearances, and are often confused about causal relationships. 6 – 12 Concrete Become capable of mental operations that allow them to Operational combine, separate, order, and transform objects and actions. There are still carried out, however, in the presence of the objects and events being thought about. 12 – 19 Formal Acquire the ability to think systematically about all logical Operational relations within a problem. Display keen interest in abstract ideas and in the process of thinking itself.
Sensorimotor Substages Sub Age (M) Description 1 0– 1½ Reflex schemas exercised: Involuntary rooting, sucking, grasping, looking 2 1½– 4 Primary circular reactions: Repetition of actions that are pleasurable in themselves 3 4– 8 Secondary circular reactions: Dawning awareness of the effects of one’s own actions on the environment, and that extended actions can produce interesting change in the environment 4 8 – 12 Coordination of secondary circular reactions: Combining schemas to achieve a desired effect (earliest form of problem solving) 5 12 – 18 Tertiary circular reactions: Deliberate variation of problem-solving means, with experimentation to see what the consequences will be 6 18 – 24 Beginning of symbolic representation: Images and words come to stand for familiar objects, accompanied by the invention of new means of problem solving through symbolic combinations
Mechanisms of Developmental Change Cultural-Context Perspective
Reciprocal Relationships Presence of milk stimulates infant sucking, which in turn triggers the release of hormones that increase milk production and release
Developmental Change Incorporates Cultural Variations l Additional sources of developmental change l l Active contribution of other people in the child’s community Cultural “designs for living” accumulated over the history of the larger social group Case in Point Bottle-feeding vs. Breast-feeding
First Postnatal Bio-Social-Behavioral Shift Occurs at 2½ Months Social Smiling!
BSB Shifts & Subsequent Periods Shift Point Conception Birth 2 ½ months 7 -9 months 24 -30 months 5 -7 years 11 -12 years 19 -21 years Developmental Period Prenatal period Early infancy Middle infancy Late infancy Early childhood Middle childhood Adolescence Adulthood
Characteristics of the Shift Biological l l l Social l l Behavioral l l Myelination of cortical and subcortical neural pathways Increased cortical control of subcortical activity Increased diversity of brain cells Increase in amount of wakefulness Decrease in proportion of active (REM) sleep Quiet (NREM) sleep begins to come first New quality of coordination and emotional contact between infants and caretakers Beginning of “crying on purpose” Better retention of learning Increased visual acuity and better visual scanning Onset of social smiling Decreased fussiness and crying Visually initiated reaching visually guided reaching