Chapter 4: Physical Development in Infancy Life-Span Development Twelfth Edition Chapter 4: Physical Development in Infancy ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Patterns of Growth: Cephalocaudal Pattern: sequence in which the earliest growth always occurs from the top downward Also applies to gains in motor development Proximodistal Pattern: sequence in which growth starts in the center of the body and moves toward the extremities ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Forebrain: portion of the brain farthest from the spinal cord; includes cerebral cortex Cerebral Cortex: folded surface covering the forebrain Cerebral cortex is divided into 2 hemispheres, each with 4 lobes Frontal lobe: voluntary movement, thinking, personality, and intentionality Occipital lobe: vision functions Temporal lobe: hearing, language processing, and memory Parietal lobe: spatial location, attention, and motor control ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Lateralization: specialization of function in one hemisphere of the cerebral cortex or the other Some functions are lateralized, some are not Complex functions involve communication between both hemispheres ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Neurons: brain nerve cells that communicate through electrical and chemical signals Axons carry signals away from the cell body Dendrites carry signals toward the cell body Myelin sheath is a layer of fat cells that insulate axons Helps electrical signals travel faster Terminal buttons release chemicals (neurotransmitters) into synapses Synapses: tiny gaps between neurons ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Changes in Neurons: Myelination: the process of encasing axons with fat cells Begins prenatally and continues into adolescence Connectivity among neurons increases New dendrites grow Connections among dendrites increase Synaptic connections increase More synaptic connections are created than will ever be used Leads to a “pruning” of unused connections ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Changes in regions of the brain: “Blooming and pruning” of synapses varies by brain region Pace of myelination varies as well ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Depressed brain activity has been found in children who grow up in a deprived environment Enriched environments promote faster brain development than deprived ones After birth: sights, sounds, smells, touches, language, and eye contact help shape the brain’s neural connections Repeated experience wires (and rewires) the brain Brain is both flexible and resilient ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Dynamic Systems View: Infants assemble motor skills for perceiving and acting Motor skills represent solutions to goals Development is an active process in which nature and nurture work together Development of nervous system Body’s physical properties and possibilities for movement Goal the child is motivated to reach Environmental support for the skill ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Development in the 2nd Year: Toddlers become more skilled and mobile Motor activity is vital to the child’s development of competence and independence By 18-24 months, toddlers can: Walk quickly or run stiffly Balance on their feet in a squat position Walk backward Stand and kick a ball without falling Jump in place ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Cultural Variations: mothers in developing countries tend to stimulate their infants’ motor skills more than mothers in more modern countries Infants can reach motor milestones slightly earlier if provided with physical guidance or given opportunities for exercise Even when activity is restricted, many infants still reach milestones at a normal age ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Fine Motor Skills: involve finely tuned movements Reaching and grasping is a significant milestone for infants Palmer grasp: grasping with the whole hand Pincer grip: grasping with the thumb and forefinger Perceptual-motor coupling is necessary for infants to coordinate grasping Experienced infants look at objects longer, reach for them more, and are more likely to mouth the objects ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Visual Preference Method: infants look at different things for different lengths of time They look at preferred objects longer Habituation: decreased responsiveness to a stimulus after repeated presentations Dishabituation: recovery of a habituated response after a change in stimulation ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Habituation and Dishabituation Studies: High-amplitude sucking Orienting response Tracking Videotaping Recording heart rate, respiration, body movement, sucking behavior, visual fixation ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Newborn’s vision is about 20/600 (an object 20 feet away appears as if it were 600 feet away) By the age of 6 months, vision is 20/100 or better Vision approximates that of an adult by the infant’s first birthday Infants show an interest in human faces soon after birth The way they gather information about the visual world changes rapidly with age ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Eleanor Gibson and Richard Walk studied development of depth perception using a “visual cliff” Infants 6-12 months old can distinguish depth Infants 2-4 months old show heart rate difference when placed on deep side of cliff Infants develop binocular depth cues by about 3-4 months of age ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Fetuses can hear and learn sounds during the last two months of pregnancy and can recognize their mother’s voice at birth Newborns: Cannot hear soft sounds as well as adults Are less sensitive to pitch Are fairly good at determining the location of a sound ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Touch and Pain: newborns respond to touch and can feel pain Smell: newborns can differentiate odors Preference for mother’s smell by 6 days Taste: sensitivity to taste may be present before birth ©2009 The McGraw-Hill Companies, Inc. All rights reserved.

©2009 The McGraw-Hill Companies, Inc. All rights reserved. Intermodal Perception: the ability to integrate information from two or more sensory modalities Babies are born with some innate abilities to perceive relations among senses Their abilities improve considerably through experience Perceptual–Motor Coupling: action guides perception, and perception guides action ©2009 The McGraw-Hill Companies, Inc. All rights reserved.