Prenatal and Infant Development Mr. Koch AP Psychology Forest Lake High School

Conception A single sperm fertilizes a single ovum (egg) to create a zygote “germinal stage” - process of rapid cell division and then differentiation At about 10 days, attaches to wall of uterus Outer cells form placenta, inner cells develop into embryo

Embryonic Stage Stage from 2-9 wks after conception Organs begin to form and function Develops heart, nervous system, stomach, esophagus, ovaries or testes Develop eyes, ears, nose, jaw, mouth lips By end have tiny arms w/ elbows, hands, fingers Legs have knees, ankles, toes

Embryo at about 6 weeks: Notice the large neural tube and the formation of the heart and other internal organs.

Embryo at approximately 7 weeks: Eyes, fingers, toes and most internal organs have formed, but are not yet fully functional.

Fetal Stage 7 month period of prenatal development, spanning 9 weeks from conception to birth Begins to look distinctly human Organs grow and start to function By 3 months: can kick, make fist, turn head, open mouth, swallow, frown In 6th month: eyelids open, has tastebuds, well-developed grasp, can breathe regularly as long as 24 hrs. at a time Could potentially survive premature birth by end of 6th month Organ systems typically functional by end of 7th month 8th & 9th month: respond to light & touch, hear outside sounds Can also learn – respond differently to sound of mother (faster heartbeat) and stranger (slower heartbeat)

Teratogens Potentially harmful agents (i.e. viruses, chemicals) that can affect prenatal development Placenta screens out most harmful substances, but these sneak through Especially harmful if during embryonic stage “critical period” in prenatal development If heart, eyes, ears, hands, feet don’t appear, cannot form later – if formed incorrectly, defects are permanent Teratogens during fetal stage affect size, behavior, intelligence, and health

Teratogens Disease Drugs (i.e. heroine, cocaine, crack) Can be born with AIDS or experience physical defects from other diseases like rubella Drugs (i.e. heroine, cocaine, crack) Can be born addicted “Crack babies” premature, underweight, tense, fussy, delayed physical growth & motor development, behavior & learning problems Smoking/nicotine Can cause respiratory problems, irritability, social/attention problems, greater risk for nicotine addiction later in life, can harm brain development Can cause reduction of nutrients that can lead to premature and underweight birth, which can cause cognitive and behavioral problems

Teratogens Alcohol Fetal Alcohol Syndrome (FAS) Can kill fetal brain cells – depresses fetal nervous system, putting at risk for birth defects & mental retardation Fetal Alcohol Syndrome (FAS) Characterized by mental retardation, possible physical malformations Behavioral and psychological problems also linked to mothers experiencing significant stress, depression, or flu in first 6 months Fortunately, vast majority of infants (>90% in western nations) are born without mental or physical problems

Newborns How do we study capabilities of infants? Very difficult – present stimuli & monitor response Eye movements, changes in heart rates, sucking rates, brain waves, body movements, and skin conductance Can see at birth Blurry, but able to see large, close objects Seem to prefer faces and seem prepared to distinguish from other visual stimuli Born with limited hearing capabilities Notice single note differences of tone, turn head toward sounds, particularly attuned to sounds of speech Similar sense of smell & taste to adults, but less developed Breast-fed infants show preference for smell of own mother to others In general, infants’ sensory abilities seem to dispose to focus attention on caregiver

Newborns Born with numerous reflexes that aid survival Involuntary, unlearned motor behaviors Ex. “rooting” reflex, sucking, etc. Most disappear in 3-4 months when brain development allows voluntary control of muscles and development of motor skills

Reflexes Rooting Sucking Swallowing Grasping Stepping Baby turns its head toward something that brushes its cheek and gropes around with mouth Sucking Newborn’s tendency to suck on objects placed in the mouth Swallowing Enables newborn babies to swallow liquids without choking Grasping Close fist around anything placed in their hand Stepping Stepping motions made by an infant when held upright

Newborns Brain development Born with overabundance of neurons, but immature (connections poorly developed) After birth, neural networks develop rapidly until puberty when “pruning” process gains importance

Newborns Brain development helps enable maturation Natural growth or change that unfolds in a fixed sequence, relatively independent of environment Must be biologically prepared for certain changes to develop Age of maturation will vary, but sequence rarely does However, research shows that once properly matured, experience can impact efficiency, effectiveness of development Once again, nature and nurture interact

Motor Development Developmental norms Ages by which an average child achieves various developmental milestones First, infants begin to roll over. Next, they sit unsupported, crawl, and finally walk. Experience has little effect on this sequence. OBJECTIVE 6| Outline four events in the motor development sequence from birth to toddlerhood, and evaluate the effects of maturation and experience on that sequence.

Maturation and Infant Memory The earliest age of conscious memory is around 3½ years (Bauer, 2002). A 5-year-old has a sense of self and an increased long-term memory, thus organization of memory is different from 3-4 years. OBJECTIVE 7| Explain why we have few memories of experiences during our first three years of life. Courtesy of Carolyn Rovee-Collier Amy Pedersen