PSY 2012 0004 Katie s Notes Chapter 5 Nature Nurture and Human Development Three types of research design employed in studying human development o Cross sectional studies compare groups of individuals of different ages simultaneously o Longitudinal studies follow a group of individuals across a span of time o Sequential designs combine cross sectional and longitudinal studies groups of people of different ages are studied at several points in a span of time Sources of bias in developmental research o Bias is systematic influence that may invalidate the results o Selective attrition Some kinds of subjects drop out for reasons that invalidate the results o Cohort effects Influence on research results from contemporaries sharing the same experience knowledge or behaviors Prenatal development Prenatal development refers to growth and changes occurring before birth A series of distinct stages based on the type of growth and changes in each o Zygote o Blastula o Gastrula o Embryo o Fetus Fertilized egg cell Hollow sphere of stem cells Stem cells fold in to form layers 2 to 8 weeks after conception 8 weeks after conception until birth Prenatal brain development o At 7 weeks the hindbrain and midbrain are developed enough to produce movements o By 36 weeks they also produce head and eye movements in response to sounds a sleep wake cycle including REM sleep o The cerebral cortex is relatively inactive at this time The maternal fetal connection o What mother consumes reaches the baby via the placenta o If her nutrition and prenatal care are deficient baby s health will be negatively affected Low birth weight and premature infants o Small and premature babies have greater risk of dying in infancy o Their brain development may be impaired o They are at higher risk of behavioral and academic problems Fetal alcohol syndrome o This occurs then the mother drinks alcohol during pregnancy o Possible effects include stunted growth of the head and body malformations of the face heart and ears nervous system damage including seizures hyperactivity learning disabilities and mental retardation 1 PSY 2012 0004 Katie s Notes Fetal alcohol effects FAE is a milder version o The child with FAE seems normal but may have impaired academic skills and mild behavioral problems o In general the more and longer mother drinks the greater the risk to the developing baby There is no safe level of alcohol consumption during pregnancy Growing neurons need constant excitation to survive Alcohol promotes GABA the main inhibitory neurotransmitter of the brain which leads to neuronal self destruction o Chemicals that agonize inhibitory synapses tranquilizers anesthetics and anti depressants should be avoided Infant s Vision At first vision is limited but newborns see far better than previously believed 2 day old infants prefer human faces o Infants look longer at female than male faces and recognize female faces more easily than male faces As voluntary control of arms and legs develops and babies start crawling a fear of heights develops related to improved depth perception Infant s Hearing stimulus Infants suck more vigorously when hearing new or stimulating sounds o Human voices are the most stimulating Habituation as they become used to sounds they have a decreased response to a repeated Dishabituation playing new sounds causes an increased response When a new stimulus increases a previously habituated response 2 PSY 2012 0004 Katie s Notes Infant s Learning and Memory At one month old infants can discriminate between some phonemes They show preference for mother s voice over other female voices o This is present at birth They may have some prenatal memory of her voice 2 3 month olds can learn responses and remember them for days afterwards such as kicking 9 month olds can learn to press a lever to move a toy train on a track and retain this memory their legs to make a mobile move for a fairly long time Jean Piaget s View of Cognitive Development Piaget thought the effect of experience on thinking depended on maturity combined with previous experiences He believed children think differently from adults o Children of varying cognitive maturity levels react to the same experience differently A child constructs new mental processes while interacting with the environment o Behavior is based on schemata an organized way of interacting with objects Example infants have a grasping schema and a sucking schema Older infants gradually add new schemata and adapt their old ones o Assimilation applying an old schema to new objects or problems Example a child who observes that animals move on their own may believe that the Sun and Moon which seem to move must be alive also o Accommodation modifying an old schema to fit a new object or problem Example a child may learn only living things move on their own is a rule with exceptions and that the Sun and Moon are not alive o Infants shift back and forth between assimilation and accommodation Equilibration is the establishment of harmony or balance between the two Piaget contended that children progress through four major stages of intellectual development The sensorimotor stage The preoperational stage The concrete operations stage The formal operations stage From birth to almost 2 years From just before 2 to 7 years From about 7 to 11 years From about 11 years forward 1 The Sensorimotor stage a During this first stage behavior consists of simple motor responses to sensory stimuli Grasping and sucking reflexes for example b Piaget thought that infants respond to what they see and hear not remember or imagine c Piaget believed that young infants lacked a concept of object permanence i The idea that objects exist even when they cannot be seen or sensed Out of sight out of existence ii A 6 9month old child reaches for a visible toy but not one that is hidden being a barrier even if the child sees someone hide the toy d Another aspect of children s progress through the sensorimotor stage is that they appear to gain some concept of self around the age of 1 3 PSY 2012 0004 Katie s Notes e Baillergeon s recent research suggests that 6 8 month olds may have a limited grasp of object permanence i Also that young infants differentiate between possible and physically impossible events Impossible event the raised screen shows a box on the track where the car would pass After the screen lowers the car goes down the slope and emerges on the other side 2 The Preoperational Stage a By the age of 1 5 2