Chapter 3: Biological foundations Genes, temperament, and more

Transcription

1 Week 3 readings Chapter 3: Biological foundations Genes, temperament, and more - 4 aspects of biology that contribute to children`s social development 1. Biological preparedness: gives babies a head start in development (visual, auditory, olfactory and tactile capacities present at birth 2. Neurological 3. Genetics 4. Differences in temperament Biological preparedness for social interaction - Babies responsiveness to other human beings increases their caregivers interest and attention and ensures the infants well-being - How are babies prepared? From biological rhythms to social rhythms Behaviour follows biological rhythms which they learn to control and regulate biological regulatory skills over the 3 months of life are able to interact with their mother in a synchronous manner showing a predictable degree of responsiveness 6-10 weeks premature babies have rhythms (sleep-wake cycles) that are not fully developed ; linked to poorer social interaction synchrony with the mother at 3 months Visual preparation for social interaction Stare longer at objects that have larger elements, movement, clear contours and a lot of contrast such as faces Mostly interested in eyes Prefer mothers face than face of a stranger Auditory preparedness for social interaction Babies can hear complex noises even before they are born --> e.g. Cat and the Hat was read twice a day for the last 6 ½ weeks of pregnancy where after births infants preferred to listen to The Cat and the Hat rather than an unfamiliar book Like a voice that is high in pitch with exaggerated pitch contours By 9 months they tune out words and sounds from other languages Smell, taste and touch Newborns can discriminate among different odours and tastes and prefer those that adults find pleasant Preference for the food flavors consumed by their mothers Sense of touch first sense to develop Beyond faces and voices: Primed to be a social partner 2-3 months infants enjoy face-to-face play with their parents - Why are babies prepared? Prepared by evolution to expect certain types of environments and to process some types of info more readily and efficiently than others

2 Adaptive and useful for survival biologically programmed to be responsive to social partners and have a set of social responses that ensures that their needs are met Neurological basis of social development - The brain Cerebrum: 2 connected hemispheres f the brain Cerebral cortex: covering layer of the cerebrum, which contains the cells that control specific functions such as seeing, hearing, moving, and thinking Frontal cortex = processing emotional info Limbic system (set of brain structures that form the inner border of the cortex) = regulation of emotion and social behaviour Amygdala (structure of limbic system) = recognition of fear and surprise expressions - Brain growth and development Brain spurts in infancy and childhood Motor cortex o 2 months, frontal motor cortex undergoes rapid change, motor reflexes like rooting and startle response disappear and ability to reach for objects improves o 8 months ability to crawl and to search for hidden objects and ppl o 12 months walking Visual cortex o 3 months looking longer at facelike stimuli and nonface stimuli Auditory cortex o More sensitive to human voices and language input from caregiver o months rapid language development Development of prefrontal cortex o 5-7 years appearance of executive processes, which give children the ability to think flexibly, act appropriately, plan and organize, control impulses and allocate attention Changes in adolescence o Puberty abrupt changes in interior limbic and paralimbic areas associated with social and emotional processing o Gradual development of executive functioning - Hemispheric specialization Cerebral hemispheres: 2 halves of the brains cerebrum Corpus collosum: band of nerve fibers that connect the 2 hemispheres of the brain Lateralization: process by which each half of the brain becomes specialized for certain functions e.g. control of speech and language by the left hemisphere and visual-spatial by the right hemisphere Begins early in life Children experience brain injury, recover functioning because their brain plasticity - Nerves and synapses

3 At birth baby has most of its neurons Neuron proliferation: rapid formation of neurons in the developing organism s brain Glial cells: supports, protects and repairs neurons; some responsible for myelination (occurs mostly in first 2 years) Neural migration: movement of neurons within the brain that ensures that all brain areas have a sufficient number of neural connections Synapses: intercellular communication exchanges info between nerve cells usually chemically Synaptogenesis: forming of synapse Brain is programmed to make more neurons than it needs 2 processes reduce the number of neurons and connections: Programmed neuronal death: naturally occurring death of immature nerve cells during early development of the nervous system Synaptic pruning: brains disposal of the axons and dendrites of a neuron that is not often stimulated - Brain development and experience 2 processes influences brain development: 1. Experience-expectant processes: universal depend on experiences that are expected in ppls normal environments such as touch, patterned visual input, sounds of language etc 2. Experience-dependent processes: unique to the individual and responsive to particular cultural, community and family experiences - Mirror neurons and the social brain Mirror neurons: nerve cell that fires both when a person acts and when a person observes the same action performed by someone else, as if the observer himself were acting Important for learning new skills through imitation and for understanding other ppls actions and intentions Linked to language acquisition, development of theory of mind skills and feelings of empathy Problems with mirror neuron system may underlie cognitive disorders and that ppl in autism have deficiency in social skills, imitation, empathy and theory of mind Mirror neuron system found in the social brain network of brain regions involved in understanding other ppl Part of the brain has increased in size in recent evolution Involved in social functions that range from recognizing faces and bodily gestures to evaluating what other ppl are thinking or feeling, predicting what they are about to do next and communicating with them Medial prefrontal cortex important in understanding our own and others communicative intentions Amygdala and superior temporal sulcus are regions of the social brain involved in processing emotional facial expressions Frontal insula (FI) active when ppl experience emotions

4 Genetics and social development - Genes contribute to shared characteristics of the human species and to differences among ppl - Human behaviour genetics: study of the relative influences of heredity and environment on individual differences in traits and abilities - Heritability factors: a statistical estimate of the contribution heredity makes to a particular trait or ability - Methods of studying genetic contributions to development Studying family members is mostly used Behaviour genetics: Adoption and twin studies Limitations: a twin in itself has an effect on social development, so results from twin studies may not be applicable to nontwin pops; identical twins are more likely than fraternal twins to experience birth defects which can also contribute to differences between them Variation is to study children whose mothers are identical twins Shared and nonshared environments Identical twins have more shared environments than fraternal twins However fraternal twins also have shared environments which include poor or well off, living in good or bad neighbourhoods etc have more nonshared environments in the different activities that they choose, temperament etc Molecular genetics: the human genome project Primary aim to locate and describe all the genes in the human genome - Models of genetic influence Transmission of traits: a basic model 2 components of this model: 1. More than one form of a gene alternate forms called alleles 2. If alleles from both parents are the same, the person is homozygous for that particular gene or for that trait; if they are different they are heterozygous Interactions among genes Interaction of multiple genes Modifier genes: genes that exert their influence indirectly by affecting the expression of other genes Environment influences gene expression Heredity does not fix behaviour but establishes a range of possible developmental outcomes that occur in different environments Reaction range: range of possible developmental outcomes established by a person s genotype in reaction to the environment in which development takes place Likelihood that a genetically based trait is influenced by the environment is affected by the stage of development at which the environmental events occur Genetic makeup helps shape the environment Genes can influence the environment

5 One way is that parents with certain genetic predispositions create a home environment that suits those predispositions and also suits and encourages these inherited predispositions in their children Passive gene environment association: environment created by parents with particular genetic characteristics encourages the expression of these tendencies in their children Evidence for this comes from 2 sources: 1) Studies using twins who are parents have demonstrated genetic influences on parenting 2) Adoption studies have demonstrated genetic links between parenting and children s behaviour Evocative gene environment association: peoples inherited tendencies elicit certain environmental responses Active gene environment association: peoples genes encourage them to seek out experiences compatible with their inherited tendencies Niche picking: seeking out environments compatible with one s genetically based predispositions Gene environment interactions (G x E) (G x E) model: ppl in the same environment are affected differently depending on their genetic makeup Gene environment feedback loops Genes and environments shape development together as genes influence environments, which in turn influence genes, in a complex feedback loop Influences are bidirectional Genes as a part of an overall system and their expression is affected by events at other levels of the system including the environment Blue box: o Gene called 5-HTT that helps regulate transmission of serotonin which is linked to an increase risk of depression, lack of self-control and drug use - Genetic anomalies Females with only one X chromosome called Turner syndrome exhibit abnormal social behaviour patterns Ppl with narrowed or pinched X chromosome called fragile X syndrome also have psychological and social problems including anxiety, depression, hyperactivity, attention deficits and abnormal communication patterns Children who lack the long arm of the 7 th chromosome have Williams syndrome have limited intelligence and visual spatial ability deficits Temperament: Causes and Consequences - Defining and Measuring Temperament Temperament: an individual s typical mode of response including activity level, emotional intensity, and attention span; used particularly to describe infants and children s behaviour

6 Study on easy, difficult and slow to warm-up babies: Difficult infants slept ad ate irregularly, became easily upset by new situations, and experienced extremes of fussiness and crying Easy babies were friendly, happy and adaptable Slow-to-warm-up babies were low in activity level an tended to respond negatively to new stimuli at first but slowly adapted to new objects and novel experiences after repeated contact with them Thomas and Chess s global temperament types: 1. Effortful control attentional functioning, inhibitory control, perceptual sensitivity, and low intensity pleasure 2. Negative affectivity fear, frustration, sadness, and discomfort 3. Extraversion surgency positive anticipation, impulsivity, high activity level, and sensation seeking - The biological basis of temperament Genetic factors In part genetically determined and that genetic influences become increasingly prominent through early childhood heredity contributes to individual differences in temperament dimensions such as emotionality, fearfulness, anxiety, activity level, attention span, persistence and sociability Infant temperament affected by prenatal environmental and environmental factors at birth Childhood temperament affected by interactions with family members Adulthood, temperament less linked to genetic factors and life experiences become more significant Neurological correlates Neurochemical molecules like, epinephrine, dopamine, vasopressin, and oxytocin seem to play a role E.g. extraversion linked to the availability of dopamine Individual differences in effortful control, impulsivity, and proneness to frustration have been linked to activity in the anterior and lateral prefrontal areas of the brain - Early evidence of temperament Temperamental characteristics appear early even prenatally After birth newborn infants exhibit differences in distress and avoidance, and a few months later, differences in how much they smile at and approach social stimuli 2-3 months babies differ in their expression of negative emotions such as anger and frustration 7-10 months babies differ in their level of fearfulness Over the next year they become able to control and regulate their expression of these emotions through effortful control Effortful control allows children to inhibit an emotion or action, facilitate an action, make plans for future actions, and detect errors in actions studied through tasks such as delaying gratification; controlled motor behaviour; controlled stopping and

7 starting; controlled attention; and controlled vocal output by 30 months they perform consistent in these tasks 45 months, effortful control is stable By age 7 children functioning as well as adults on attention tasks reflecting effortful control - Consequences and correlates of temperament Consequences for children social development Those who are irritable, difficult, impulsive and emotional experience higher rates of problems in later life Children low in extraversion-surgency more likely to internalize problems: type of childhood behaviour problem in which the behaviour is directed at the self rather than other including fear, anxiety, depression, loneliness, and withdrawal Children with poor effortful control exhibit more externalizing problems: type of childhood behaviour problem in which the behaviour is directed at others, including hitting, stealing, vandalizing and lying Children with high negative emotionality may have both kinds of problems Many factors may contribute to relations between temperament and later problems 1. Children with difficult temperaments may find it more difficult to adapt to environmental demands and may be more affected by stress and the toll it takes on emotional well-being 2. Children with difficult temperaments may elicit more adverse reactions from other ppl and thus suffer the psychological damage caused by harsh parenting and social rejection these children often serve as targets of parental irritability, therefore, effect of temperament is indirect: Behavioural outcomes are the result of the differential experiences of children with different temperaments 3. Temperament may interact with conditions in the environment, in a T x E interaction e.g. if parents under stress, have marital conflicts, hostile and lack supportive family or friendship network, children s difficult temperament are more likely to develop externalizing problems than if family is peaceful + positive Children with the double whammy (insensitive mother + difficult temperament) more likely to develop aggression and acting out problems, anxiety and depression and academic and social problems compared to a child with only one of these disadvantages Temperamental fearful children whose parents use harsh discipline = elevated levels of depression, poor emotional regulation, low levels of consciousness Children with timid temperaments whose mothers are unsupportive, negative, or depressed are more likely to continue to be fearful and socially withdrawn; have more negative moods and develop maladaptive ways of regulating their negative emotions Thomas and Chess termed this match between the child s temperament and the child-rearing environment goodness of fit Temperament traits defined as narrower lower-level traits that are substrates if the Big Five personality factors

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