1. Review the Brief Chapter Summary.
2. Answer and submit the Learning Objectives. Write the question and then the answer.
3. Complete and submit the Learning Activity. Write the question and then the answer.
BRIEF CHAPTER SUMMARY
During the first two years, body size increases dramatically, following organized patterns of growth. The skull also
grows rapidly, accommodating large increases in brain size. Neurons in the brain form an elaborate communication
system, sending messages to one another by releasing neurotransmitters across the synapses. MyelinationÑthe
coating of neural fibers with myelinÑimproves the efficiency of message transfer. Neurophysiological methods that
detect brain-wave activity allow researchers to identify relationships between the brain and psychological
development.
The cerebral cortex surrounding the rest of the brain is the largest and most complex brain structure. Each
hemisphere specializes in different functions, but brain plasticity allows some recovery of abilities lost to damage in
one hemisphere. During sensitive periods in brain development, the rapidly growing brain must receive appropriate
stimulation in order to reach its full potential. Rapid brain growth also causes substantial changes in organization of
sleep and wakefulness during the first two years.
Various factors affect early physical growth. Heredity contributes to height, weight, and rate of physical
maturation. Nutrition is crucial: Rapidly growing babies need extra calories to keep their developing organs
functioning properly. Breast milk, which is ideally suited to meet infantsÕ needs, is especially important in promoting
infant survival and health in poverty-stricken regions. Rapid weight gain in infancy appears to be related to later
overweight and obesity; malnutrition in the early years can lead to permanent stunting of physical growth and of brain
development. Affection and stimulation are also essential for healthy physical growth.
Babies are born with built-in learning capacities that allow them to benefit from experience immediately after
birth. Classical conditioning, operant conditioning, habituation and recovery, and imitation are important early
learning capacities that infants use to explore their physical and social worlds.
Motor development, like physical growth, follows an organized sequence, with large individual differences in
rate of motor progress. According to dynamic systems theory, mastery of motor skills involves acquiring increasingly
complex systems of action in which each new skill is a joint product of central nervous system development, the
bodyÕs movement possibilities, the goals the child has in mind, and environmental supports for the skill. Cultural
variations in infant rearing practices also influence motor development. Of all motor skills, reaching may play the
greatest role in infant cognitive development because it opens up a new way of exploring the environment. Reaching
improves as depth perception advances and infants gain control of body movements. Early experience also plays a
role.
Hearing and vision undergo major advances in the first year. Babies begin to organize sounds into complex
patterns, detecting regularities that facilitate later language learning. Newborns prefer human speech to nonspeech
sounds, and infants have a remarkable ability to extract regularities from complex, continuous speech, which prepares
them to utter their first words around age 12 months. Visual development is supported by maturation of the eye and
visual centers in the cerebral cortex. Depth perception develops gradually, helping infants avoid falling. Pattern
perception begins at birth; newborns prefer to look at patterned rather than plain stimuli. BabiesÕ tendency to look for
structure in a pattern stimulus also applies to face perception; they quickly learn to prefer their motherÕs face to that of
an unfamiliar woman. Size constancy and object constancy also begin in the first week of life. Through intermodal
perception, babies perceive input from different sensory systems in a unified way. Perception is guided by the
discovery of affordancesÑthe action possibilities that a situation affords.
After reading this chapter, you should be able to:
5.l Describe changes in body size, body proportions, and muscle-fat makeup during the first two years of life. (pp. 166-167)
5.2 Discuss skeletal growth during the first two years of life, including the growth of the skull and the appearance of teeth. (pp. 167-168)
5.3 Describe brain development during infancy and toddlerhood at the level of individual brain cells and at the level of the cerebral cortex. (pp. 168-172)
5.4 Summarize research on brain lateralization and brain plasticity. (pp. 172-173)
5.5 Describe research findings related to the existence of sensitive periods in brain development, and note the evidence of brain growth spurts and need for appropriate stimulation. (pp. 173-176)
5.6 Describe current methods of measuring brain functioning, and identify which measure is most appropriate during infancy and toddlerhood. (pp. 170-171)
5.7 Explain how the organization of sleep and wakefulness changes over the first two years. (pp. 176-178)
5.8 Discuss the impact of heredity on early physical growth. (p. 178)
5.9 Discuss the nutritional needs of infants and toddlers, the advantages of breastfeeding, and the extent to which chubby babies are at risk for later overweight and obesity. (pp. 178-180)
5.10 Discuss the impact of severe malnutrition on the development of infants and toddlers, and cite two dietary diseases associated with this condition. (pp. 180-182)
5.11 Describe the growth disorder known as nonorganic failure to thrive, noting common symptoms and family circumstances surrounding the disorder. (p. 182)
5.12 Explain how infants learn through classical conditioning, operant conditioning, habituation and recovery, and imitation. (pp. 183-187)
5.13 Describe the general course of motor development during the first two years, along with factors that influence it. (pp. 187-188)
5.14 Explain the dynamic systems theory of motor development, highlighting cultural variations in motor development. (pp. 189-190)
5.15 Describe the development of reaching and grasping, and explain how early experiences affect these skills. (pp. 190-193)
5.16 Summarize the development of hearing in infancy, giving special attention to speech perception. (pp. 193-194)
5.17 Summarize the development of vision in infancy, with particular attention to depth perception and pattern
perception. (pp. 195-200)
5.18 Discuss the development of object perception during the first year of life. (pp. 200-201)
5.19 Explain the concept of intermodal perception. (p. 202)
5.20 Explain the GibsonsÕ differentiation theory of perceptual development. (pp. 202-203)
LEARNING ACTIVITY 5.1: Creating a Pamphlet for Parents: Supporting Infant and Toddler Brain Development (pp. 168-176)
Review research on brain development, carefully focusing on the importance of appropriate stimulation during the first 2 years. Next, create a pamphlet for parents about supporting their youngsterÕs early physical development. Do not only focus on what parents should do, but also explain the consequences of overstimulating babies and toddlers.