1. CHAPTER FOUR PHYSICAL, SENSORY AND PERCEPTUAL DEVELOPMENT IN INFANCY

2. Copyright © 2009 Pearson Education Canada 4-2 I. PHYSICAL CHANGES During infancy, babies grow 25 to 30 centimetres and triple their body weight in the first year At about age 2 for girls and age 2½ for boys, toddlers are half as tall as they will be as adults Two-year-olds have proportionately much larger heads than do adults—needed to hold their nearly full-sized brains

3. Copyright © 2009 Pearson Education Canada 4-3 A. The Brain and the Nervous System Synapses: connections between neurons –Synaptogenesis (creation of synapses) is followed by a period of synaptic pruning to make the nervous system more efficient –Plasticity: the brain’s ability to reorganize neural pathways and connections Myelinization: –Myelin gradually covers individual axons and electrically insulates them from one another, improving the conductivity of the nerve –Reticular formation: the part of the brain that regulates attention isn’t fully myelinized until the mid- 20’s

4. Copyright © 2009 Pearson Education Canada 4-4 Parts of the Human Brain Developed at and After Birth

5. Copyright © 2009 Pearson Education Canada 4-5 B. Reflexes and Behavioural States Adaptive reflexes, such as sucking, help newborns survive; some adaptive reflexes persist throughout life Primitive reflexes are controlled by primitive parts of the brain; these reflexes disappear by about 6 months of age Babies’ senses of hearing, taste, touch, and smell are well-developed (continued)

6. Copyright © 2009 Pearson Education Canada 4-6 NEWBORN REFLEXES REFLEXDESCRIPTION BabinskiWhen the sole of the foot is stroked, the infant’s toes fan out and up. This reflex disappears around 12 months. GraspingWhen an object touches the palm of the hand, the infant grasps it. This reflex is strong for the first few months and becomes a voluntary response by 5 months. MoroA sudden noise or loss of support causes the infant to arch the back and throw the arms and legs out and then bring them back in. This reflex disappears after 4 or 5 months. PlantarAn infant curls his toes under when an object is pressed under them. This reflex disappears by 12 months. RootingA soft touch on her cheek will cause an infant to turn toward the touch and open her mouth in an attempt to suck. This reflex disappears by 3 months. Tonic neckWhen an infant is placed on her back with her head to one side, she will extend the arm and leg on that side and flex the opposite arm and leg. This reflex looks like a fencing position and disappears by 4 months.

7. Copyright © 2009 Pearson Education Canada 4-7 Reflexes and Behavioural States (continued) Behavioural States: States of Consciousness: –Patterns of sleep and wakefulness stabilize with age –Neonates sleep 80% of the time. –By 8 weeks, babies will begin to sleep through the night –By 6 months, babies are sleeping 14 hours per day –Clear nighttime patterns and daytime naps are established (continued)

8. Copyright © 2009 Pearson Education Canada 4-8 THE BASIC STATES OF INFANT SLEEP & WAKEFULNESS

9. Copyright © 2009 Pearson Education Canada 4-9 Reflexes and Behavioural States (continued) Cries –Basic cry signals hunger – rhythmical pattern –Anger cry – louder and more intense –Pain cry – very abrupt onset Cross-cultural studies suggest crying increases until 6 weeks then tapers off Prompt attention to crying in the first three months leads to less crying later Colic: an infant behaviour pattern of unknown cause, involving intense daily bouts of crying, totalling 3 or more hours a day for several months

10. Copyright © 2009 Pearson Education Canada 4-10 C. Developing Body Systems and Motor Skills Bones –Increases in length of long bones underlie increases in height –Changes in number and density of bones are responsible for improved coordination –Ossification The process of hardening of bones Begins during prenatal development Continues through puberty Motor development depends on ossification (continued)

11. Copyright © 2009 Pearson Education Canada 4-11 Developing Body Systems and Motor Skills (continued) Muscles –Muscle fibres are virtually all present at birth –Muscles are initially small and have a high ratio of water to muscle –high fat content declines to adult levels by age 1 Lungs and Heart –Improvements in lung efficiency and increasing strength of heart muscles provide the two-year-old with greater stamina than that of the newborn (continued)

12. Copyright © 2009 Pearson Education Canada 4-12 Developing Body Systems and Motor Skills (continued) Motor Skills –Locomotor skills (gross motor) – crawling –Nonlocomotor skills – controlling head movements –Manipulative skills (fine motor control) – use of hands and fingers –Milestones don’t always follow cephalocaudal and proximodistal models (continued)

13. Copyright © 2009 Pearson Education Canada 4-13 Milestones of Motor Development in the First Two Years

14. Copyright © 2009 Pearson Education Canada 4-14 Developing Body Systems and Motor Skills (continued) Explaining Motor Skill Development –Virtually all children follow the same sequence of motor skill development –Developmentally delayed children just do so more slowly –Maturation of some kind seems to be occurring –Experience in normal environments influences motor development (continued)

15. Copyright © 2009 Pearson Education Canada 4-15 Developing Body Systems and Motor Skills (continued) Gender Differences –Girls are ahead during infancy Slight advantage in manipulative skills –Boys have more developmental delays, and have higher mortality rates –Boys are typically more active Clear preference for rough and tumble play More aggressive than girls by the end of the second year

16. Copyright © 2009 Pearson Education Canada 4-16 D. Health Promotion and Wellness Nutrition –Breast-feeding is substantially superior nutritionally to bottle-feeding Contributes to more rapid weigh gain and size Breastfed infants less likely to suffer from common illnesses Stimulates better immune system functioning (continued)

17. Copyright © 2009 Pearson Education Canada 4-17 Health Promotion and Wellness (continued) Nutrition (continued) –preterm babies need extra supplementation to augment breast milk –maternal medications or the mother’s health may make breast feeding impossible –mother-infant social interactions appear to be identical if formula-fed babies are given the same maternal attention (continued)

18. Copyright © 2009 Pearson Education Canada 4-18 Health Promotion and Wellness (continued) Macronutrient malnutrition Diet that contains too few calories Leading cause of death in children under 5 –Marasmus Severe calorie deficit Extremely small Permanent brain damage –Kwashiorkor Diet too low in protein Chronically ill with large amounts of water retention in belly (continued)

19. Copyright © 2009 Pearson Education Canada 4-19 Health Promotion and Wellness (continued) Micronutrient Malnutrition –Deficiency of certain vitamins and/or minerals –The most common form of malnutrition in industrialized countries –Canada is an exception due to food fortification of the past 50 years –Mortality can be reduced by 23% by supplying young children with Vitamin A (continued)

20. Copyright © 2009 Pearson Education Canada 4-20 Health Promotion and Wellness (continued) Health Care and Immunizations –Infants need frequent medical check-ups –Routine immunization should commence at two months of age and continue through childhood and adolescence –A full set of immunizations includes hepatitis, diphtheria/tetanus/pertussis, influenza, polio, pneumonia, meningitis, measles, and mumps & rubella virus vaccine (continued)

21. Copyright © 2009 Pearson Education Canada 4-21 Health Promotion and Wellness (continued) Illnesses in the First Two Years –The average baby has seven respiratory illnesses in the first year of life –Babies in day-care centres have about twice as many infections as those reared entirely at home, with those in small-group day care falling somewhere in between –Infants who have chronic ear infections are more likely than their peers to have learning disabilities and language deficits during the school years

22. Copyright © 2009 Pearson Education Canada 4-22 E. Preterm and Low-Birth-Weight Infants Infants born before 32 weeks gestation may not have adaptive reflexes Many preterm infants must be fed intravenously or through a tube inserted into the esophagus or stomach Infants born preterm or with low-birth-weight move more slowly through all the developmental milestones They are about ten to 15 weeks behind their full- term peers on most physical skills By age two or three, the physically normal preterm baby will catch up with his peers

23. Copyright © 2009 Pearson Education Canada 4-23 Preterm Birthrates (Ontario 2000)

24. Copyright © 2009 Pearson Education Canada 4-24 F. Post-term Infants Infants born 42 weeks or more after conception are referred to as post-term Post term babies have increased risk of mortality The incidence of high-risk post-term deliveries dropped by 75% between 1991 and 2000 in Canada to an average of 1.2%

25. Copyright © 2009 Pearson Education Canada 4-25 Post Term Birthrates (Canada, 2000)

26. Copyright © 2009 Pearson Education Canada 4-26 G. Infant Mortality in Canada Sudden infant death syndrome (SIDS): the sudden and unexpected death of an apparently healthy infant SIDS is the leading cause of death between 29 days and one year of age (over 29% of deaths) Some of the key factors are: –Sleeping in a prone position (on their front) or on their side –Smoking by mothers during pregnancy, or by anyone in the home after the infant’s birth. Babies exposed to such smoke are about four times as likely to die of SIDS as are babies with no smoking exposure –Quilts, duvets, pillows, soft toys, and crib bumpers that may cover the infant’s head –The incidence is higher for male babies –The incidence is higher in low-income families

27. Copyright © 2009 Pearson Education Canada 4-27 Infant mortality by income

28. Copyright © 2009 Pearson Education Canada 4-28 II. Sensory Skills Newborns and young infants have far more sensory capacity than physicians or psychologists thought even as recently as a few decades ago

29. Copyright © 2009 Pearson Education Canada 4-29 A. Vision Visual acuity is poor at first but develops rapidly –Near objects are seen clearly Tracking –The process of following a moving object –Initially inefficient but improves rapidly Colour Vision –Red, green and blue clearly present by 1 month –Infant’s ability to sense colour almost identical to an adult’s (continued)

30. Copyright © 2009 Pearson Education Canada 4-30 B. Hearing and Other Senses Auditory Acuity –Newborns hear adult voices well. –High-pitched noises need to be loud to be heard. –Infants can locate the direction of some sounds at birth. Smelling and Tasting –Newborns react differently to each basic taste as early as birth. –Smell has nearly unlimited variations. Touch and Motion –Best developed of all senses

31. Copyright © 2009 Pearson Education Canada 4-31 Steiner’s experiments on taste response

32. Copyright © 2009 Pearson Education Canada 4-32 III. Perceptual Skills What does a baby do with sensory information? Very young infants pay attention to and respond to patterns and individual events.

33. Copyright © 2009 Pearson Education Canada 4-33 A. Explaining Perceptual Development Innate (nativist) aspects –newborns have very impressive sensory capabilities Experiential aspects –Some minimum exposure to sensory stimuli is required for normal development Integrating Nativism and Empiricism –Both nature and nurture are involved Studying perceptual development –Preference Technique –Habituation/Dishabituation –Operant Conditioning

34. Copyright © 2009 Pearson Education Canada 4-34 B. Looking Early Visual Stimulation –There are critical periods of time in early infancy and beyond when an infant or child needs a specific quality of visual stimulation in order to develop normal visual perception (continued)

35. Copyright © 2009 Pearson Education Canada 4-35 Looking (continued) Depth Perception –Binocular cues Involve both eyes The closer the object is, the more the view from the two eyes differs. Information from eye muscles tells about distance. –Monocular cues Input from one eye Interposition: one object is in front of another Linear perspective: lines get closer together as they get farther away –Kinetic cues Motion from objects or the eyes (continued)

36. Copyright © 2009 Pearson Education Canada 4-36 Looking (continued) What Babies Look at –Babies initially scan for light/dark contrast –At 2 months, babies scan entire objects to identify things –Caron and Caron (1981) suggest that by 3 – 4 months babies can find and pay attention to patterns (continued)

37. Copyright © 2009 Pearson Education Canada 4-37 Looking (continued) Faces: An example of responding to a complex pattern –NOT uniquely interesting to infants –Clearly prefer attractive faces –Prefer the mother’s face from the earliest hours of life –Infants with visual limitations (e.g. cataracts) have problems identifying faces in later life

38. Copyright © 2009 Pearson Education Canada 4-38 Studying Sensitivity to Facial Differences

39. Copyright © 2009 Pearson Education Canada 4-39 C. Listening Discriminating Speech Sounds –At 1 month, infants can discriminate between single syllables such as pa and ba –At 6 months, they can discriminate between two- syllable words –By 3 months, they recognize the sound despite who says it (male, female, young or old) –Infants can discriminate between ‘real’ and ‘nonsense’ words –At 6 months, they can distinguish sound contrasts in any language; by 1 year old, this ability fades (continued)

40. Copyright © 2009 Pearson Education Canada 4-40 Listening (continued) Discriminating Individual Voices –Newborns can discriminate mother’s voice from another female, but not father’s from another male –Mother’s voice is preferred –Babies learn this in utero Discriminating Other Sound Patterns –Babies recognize melody patterns by 6 months –Newborns recognize categories of songs, as well as knowing who the singer is singing to

41. Copyright © 2009 Pearson Education Canada 4-41 D. Combining Information from Several Senses Intersensory Integration –The coordination of information from 2 or more senses Cross-Modal Transfer –The transfer of information from one sense to another Piaget thought these skills did not develop until late in the first year, but Gibson & Gibson and others argue that some of each skill is built in at birth Both intersensory integration and cross-modal transfer experience are required for learning to take place at a normal rate