Chapter 3 Developing Through the Life Span Prenatal development and the competent newborn

Developmental Psychology 3 issues are important to developmental psychologists: Nature and nurture continuity Stability and change Developmental Psychologists study the life cycle, from conception to death. They look at how we develop physically, cognitively, and socially.

The Nature of Nurture Heredity: Genetic transfer of characteristics from parents to offspring Genome: Complete instructions for making an organism, consisting of all the genetic material in that organism’s chromosomes Parents everywhere wonder: Will my baby grow up to be peaceful or aggressive? Homely or attractive? Successful or struggling at every step? What comes built in, and what is nurtured—and how? Research reveals that nature and nurture together shape our development—every step of the way.

Genetics Genes are DNA segments that, when expressed (turned on), direct the production of proteins and influence our individual biological development. Contained in the nucleus of each cell in your body are chromosomes. Each chromosome contains a coiled chain of the molecule DNA. Genes are DNA segments that, when expressed (turned on), direct the production of proteins and influence our individual biological development.

Environment & Gene Expression life experiences lay down epigenetic marks, which are often organic molecules These molecules can block the expression of any gene in the DNA segment they affect Epigenetics explores the nature–nurture meeting place and studies how the environment can cause genes to be either active (expressed) or inactive (not expressed) Epigenetics - the study of environmental influences on gene expression that occur without a DNA change.

Conception Woman: releases a mature egg at ovulation Man: 200+ million sperm are deposited during intercourse within a few hours, the egg’s nucleus fuses with the sperm’s nucleus At birth, the woman has all of the eggs she will need for life… the man, however, will produce sperm continually from puberty, 24/7 at a rate of 1000/second! The woman’s egg: 85,000x the size of a single sperm The sperm releases enzymes to help it break through the egg’s wall The egg, meanwhile, blocks out all other sperm while sending out feelers to pull in the “winning sperm”

Prenatal Development Zygote – fertilized eggs After 10 days: the cells attach to mother’s uterine wall This forms the placenta – it passes nourishment to the embryo Embryo: after 2 weeks; has a noticeable heartbeat & red blood cells For the next 6 weeks: organs, spinal development, arm/leg growth, proportions change Fetus: after 9 weeks, embryo has taken on human characteristics For ZYGOTE: Fewer than ½ of these survive past the first two weeks post-conception. Week 1: cells in the zygote split until there are about 100 cells (7 divisions). After this, the cells begin to differentiate (to specialize in structure and function). This specialization is directed by your genes.

Prenatal Development zygote embryo fetus

Lennart Nillson Photography 24 days no skeleton heart beat: day 18

Lennart Nillson Photography 5 weeks / 9mm face begins to form

Lennart Nillson Photography 40 days

Lennart Nillson Photography 8 weeks

Lennart Nillson Photography 10 weeks

Lennart Nillson Photography 16 weeks hands explore the body

Lennart Nillson Photography 18 weeks / 14 cm perceive sound from outside world

Lennart Nillson Photography 26 weeks

Lennart Nillson Photography 6 months

Threats to the Fetus Harm can come to the fetus when the placenta admits teratogens: agents that can harm embryo/fetus during prenatal stage. Drug addictions AIDS virus nicotine / air pollution prescription drugs alcohol

Fetal Alcohol Syndrome There is no known safe amount of alcohol for a mother to drink while pregnant. Alcohol depresses activity in both mother and fetus’ central nervous systems. Fetal Alcohol Syndrome (FAS) Physical and mental abnormalities in children caused by a pregnant woman’s heavy drinking In severe cases, signs include a small, out-of- proportion head and abnormal facial features

The Competent Newborn automatic reflex responses that support survival Cries to elicit help and comfort Searches for sights and sounds linked to other humans, especially the mother Smells and sees well and uses sensory equipment to learn Has a biologically rooted temperament We have learned that babies are more aware than previously thought: study this via habituation we look towards human voices we gaze longer at a face-like image we prefer to look at objects 8-12” away (same distance to mother’s eyes while feeding) perceptual abilities continue to develop during first month can distinguish mother’s odour mother’s voices encourage more voracious sucking on a pacifier

Reflexes rooting reflex: trigger: a gentle stroke on the newborn’s cheek response: baby turns toward the touch, mouth open duration: until baby is 3-4 mo. old reason: helps baby find food

Reflexes Moro reflex (startle reflex): baby cries and extends legs, arms, fingers, arches back, then retracts arms and legs duration: until baby is 4-6 mo. old reason: baby’s first attempts to protect self from harm

Reflexes Walking reflex: trigger: hold baby upright with feet on a flat surface response: baby lifts one foot, then the other as if walking duration: about 2 mo. reason: may prepare baby developmentally for walking later on

Newborns prefer faces When shown these two images with the same three elements, newborns spent nearly twice as long looking at the face-like image on the left Newborns—average age just 53 minutes in one study—seem to have an inborn preference for looking toward faces