Social Development Chapter 3 Biological Foundations: Roots in Neurons and Genes Aspects of biology that underlie social behavior… ◼ Hormones ◼ Brainwaves ◼ DNA ◼ Physical appearance ◼ Reflexes and unconditioned responses Biological Foundations of Social Interaction ◼ Biological “preparedness” for social interaction ◼ Neurological foundations ◼ Genetics ◼ Differences in temperament Biological “Preparedness” for Social Interaction: How are babies prepared? ◼ From biological rhythms (e.g., sleep-wake cycle) to social rhythms ❑ ❑ Acquisition of biological regulatory skills → Interactional synchrony Development of biological rhythms that help babies deal with the time-based nature of social interaction Biological “Preparedness” for Social Interaction: How are babies prepared? ◼ Visual preparation for social interaction ❑ Babies attracted to visual social stimuli ◼ Faces, especially the eyes How infants scan the human face. (a) A 1-month-old baby focuses on the outer perimeter of the face, although also showing some interest in the eyes. (b) A 2-month-old scans more broadly and focuses on the features of the face, paying attention to the eyes and mouth, which suggests that some pattern detection may be occurring. (Source: Maurer & Salapatek, 1976.) Maurer, D., & Salapatek, P. (1976). Developmental changes in scanning of faces by young infants. Child Development, 47, 523–527. This material is reproduced with permission of John Wiley & Sons, Inc. Biological “Preparedness” for Social Interaction: How are babies prepared? ◼ Auditory preparedness for social interaction ❑ Well developed before birth ◼ ❑ Study: The Cat in the Hat Prefer high pitch and exaggerated contours ◼ Hi-swee-eet-ee ❑ Adults speak in shorter sentences and more slowly – “baby talk” ❑ Become attuned to native language by 9 months Biological “Preparedness” for Social Interaction: How are babies prepared? ◼ Smell, taste, and touch ❑ ❑ Newborns can discriminate among different odors and tastes and prefer those that adults find pleasant Prefer mother’s smell ◼ ❑ Facilitates development of relationship Sense of touch develops early ◼ Touch has soothing effect Biological “Preparedness” for Social Interaction: How are babies prepared? ◼ Beyond faces and voices: Primed to be a social partner ❑ Infants prefer face-to-face play to other activities ❑ Capable of regulating interactions with gaze ◼ ❑ If too stimulating, infants turn away, cry, or distract themselves Some infant-parent dyads have difficulty ◼ Cocaine exposed infants, depressed mothers What do babies learn from face-to-face interactions? ◼ Adults are responsive to them ◼ They can control other people’s behavior ◼ They can alter the course of the interaction with emotional expression ◼ Turn taking ◼ Rules of social exchanges Biological “Preparedness” for Social Interaction: Why are babies prepared? ◼ Evolutionary Theory ❑ ❑ ❑ Preparedness is adaptive and useful for ensuring the survival of the human infant and more generally, the species Infants are biologically “programmed” for social interactions that ensure that their needs are met Modern evolutionary theorists assume that development depends on being born into and reared in a species–typical environment that supports adaptive behaviors such as the ability to send, receive, and understand social messages Neurological Bases of Social Development ◼ The Brain ❑ Cerebrum – the two connected hemispheres of the brain ◼ ◼ ❑ Largest part of the human brain Allows for attributes that make us human (e.g., speech, self-awareness) Cerebral cortex – the covering layer of the cerebrum, which contains the cells that control specific functions such as seeing, hearing, moving, and thinking The cortex is divided into four lobes—frontal, temporal, occipital, and parietal—and specific areas within the lobes tend to specialize in particular functions. (Source: Postlethwait & Hopson, 1995.) Republished with permission of McGraw-Hill Companies, Inc. From Postlethwait, J. H., & Hopson, J. L. (1995). The nature of life (3rd ed.). New York: McGrawHill. Permission conveyed through Copyright Clearance Center, Inc. Neurological Bases of Social Development: Brain Growth and Development ◼ Rapid prenatal and infant growth ❑ Newborn brain weighs ¼ of adult brain ❑ 6-month-old infant brain weighs ½ of adult brain ❑ 2-year-old brain weighs ¾ of adult brain Neurological Bases of Social Development: Brain Growth and Development ◼ Growth Spurts in infancy and childhood ◼ Motor cortex Birth to 2 months – shift from reflexes to voluntary control of movement ❑ 8 months – ability to crawl and search for hidden objects ❑ 12 months – walking ❑ How do these developmental shifts change social interaction? Neurological Bases of Social Development: Brain Growth and Development ◼ Growth Spurts in infancy and childhood ◼ Visual cortex ❑ 3 months – look longer at facelike vs. non-facelike stimuli ◼ Auditory cortex ❑ 18 and 24 months – language development ◼ Prefrontal cortex ❑ 5-7 years – development of executive processes How do these developmental shifts change social interaction? Neurological Bases of Social Development: Brain Growth and Development Growth Spurts in adolescence ◼ Interior limbic, paralimbic, amygdala, medial prefrontal cortex ❑ ◼ Puberty – changes in social and emotional processing Lateral prefrontal region ❑ Puberty to early adulthood – improvements in executive function © Barbara Smaller/CondeNast Publications/www.cartoonbank.com. Neurological Bases of Social Development: Hemispheric Specialization ◼ Cerebral hemispheres – The two halves of the brain’s cerebrum, left and right Anatomically different ❑ Control different functions ❑ ◼ Corpus callosum – The band of nerve fibers that connects the two hemispheres of the brain ◼ Hemispheric lateralization – The process by which each half of the brain becomes specialized for certain functions Hemispheric Lateralization ◼ ◼ ◼ Left Hemisphere Right side of body “Approach” emotions such as joy, interest, and anger Language processing ◼ ◼ Right Hemisphere Left side of body Visual-spatial information nonspeech sounds ❑ perception of faces ❑ ◼ ◼ Processing of emotional information (facial expressions ) “Avoidant” emotions such as distress, fear and disgust Hemispheric Lateralization ◼ Has a genetic component ❑ ◼ Begins early in life, but because not complete; younger children have greater brain plasticity ❑ ◼ Parents and children have similar levels of language lateralization If left hemisphere damaged in infancy, child can still develop almost normal language ability Even adults have plasticity ❑ Adult brain has capacity to regenerate nerve cells Neurological Bases of Social Development: Neurons and Synapses ◼ Neuron – A cell in the body’s nervous system, consisting of a cell body, a long projection called an axon, and several shorter projections called dendrites; neurons send and receive neural impulses, or messages, throughout the brain and nervous system ◼ Neuron proliferation – The rapid formation of neurons in the developing organism’s brain ◼ Glial cell – A cell that supports, protects, and repairs neurons ◼ Myelination – The process by which glial cells encase neurons in sheaths of the fatty substance myelin ◼ Neural migration – The movement of neurons within the brain that ensures that all brain areas have a sufficient number of neural connections Neurological Bases of Social Development: Neurons and Synapses ◼ Brain has most of its neurons (100-200 billion) at birth ❑ ◼ Most present by the 7th month after conception Neuron proliferation occurs during the embryonic period ❑ About 250,000 new neurons are added every minute ◼ Increase in brain size after birth results from growth of neurons and connections between them as well as growth of the glial cells and the myelination process ◼ Neurons are always on the move as they migrate to their final locations in the brain guided by neurochemical processes Neurological Bases of Social Development: Neurons and Synapses ◼ Synapse – A specialized site of intercellular communication that exchanges information between nerve cells, usually by means of a chemical neurotransmitter ❑ ◼ Synapses are as essential as the neurons themselves Synaptogenesis – The forming of synapses begins early in prenatal development ❑ ❑ At birth- 2,500 synapses for every neuron in the brain’s visual cortex where the number of synapses per neuron is multiplied six times within the first 2 years of life At age 2 – 15,000 synapses for every neuron Neurological Bases of Social Development: Neurons and Synapses ◼ Programmed neuronal death – The naturally occurring death of immature nerve cells during early development of the nervous system ◼ Synaptic pruning – The brain’s disposal of the axons and dendrites of a neuron that is not often stimulated Neurological Bases of Social Development: Neurons and Synapses ◼ The brain is programmed to create more neurons and connections than it needs ◼ Programmed neuronal death eliminates immature neurons surrounding new synapses which provides more space at these crucial loci of information transmission ◼ Synaptic pruning disposes of understimulated neurons’ axons and dendrites which frees space for new synaptic connections ◼ The goals of neuronal death and synaptic pruning are to increase the speed, efficiency, and complexity of transmissions between neurons and to allow room for new connections to form Neurological Bases of Social Development: Brain Development and Experience Experience-dependent process – Brain processes that are unique to the individual and responsive to particular cultural, community, and family experiences ◼ Experience-expectant process – Brain processes that are universal, experienced by all human beings across evolution ◼ Children in unstimulating orphanages also have reduced brain activity and less connectivity between regions of the brain Neurological Bases of Social Development: Mirror Neurons and the Social Brain ◼ Mirror neuron – A 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 or herself were acting ❑ Example: fMRI recordings show that when a person observes another person’s physical action, activation of the motor cortex occurs ❑ Important for learning new skills by imitation ❑ Important for understanding other’s actions and intentions ❑ Linked to language acquisition, development of theory-ofmind, and empathy The Social Brain These brain regions are involved in social functions that range from recognizing faces and bodily gestures to evaluating what other people are thinking or feeling, predicting what they are about to do next, and communicating with them Reprinted by permission from Macmillan Publishers Ltd. Blakemore, S.-J. The social brain in adolescence. Nature Reviews Neuroscience, 9, 267–277. (fig 1, p. 269) ©2008. Blakemore, S.-J. (2008). The social brain in adolescence. Nature Reviews Neuroscience, 9, 267–277. (2008). Regions in the “social brain.” Regions include the medial prefrontal cortex (mPFC), the temporoparietal junction (TPJ), the posterior superior temporal sulcus (pSTS), the inferior frontal gyrus (IFG), the interparietal sulcus (IPS), the anterior cingulate cortex (ACC), the anterior insula (AI), the amydala, and the frontal insula (FI). (Source: Blakemore, 2008.) How the Social Brain Develops ◼ All regions in the adult social brain show partial responses in infancy ❑ Example: prefrontal regions are activated when babies process faces but mature response not seen until age 1 ❑ Suggests that the brain is adapted to develop within a social context and that this context contributes to specializations in the adult cortex ◼ Activation in the mPFC decreases in late childhood and adolescence and is replaced by activation of specialized subregions of the mPFC in adults ◼ In addition to becoming more specialized, the different cortical regions of the social brain become orchestrated into networks as development proceeds Genetics and Social Development ◼ Gene – A portion of DNA located at a particular site on a chromosome and coding for the production of a specific type of protein ◼ Human behavior genetics – The study of the relative influences of heredity and environment on individual differences in traits and abilities ◼ Heritability factor – A statistical estimate of the contribution heredity makes to a particular trait or ability ◼ Genotype – The particular set of genes a person inherits from his or her parents ◼ Phenotype – The visible expression of the person’s particular physical and behavioral characteristics; created by the interaction of a person’s genotype with the environment Genetics and Social Development ◼ Genetic Transmission Chromosomes located in the nucleus of each cell ❑ Genes located on particular sites of the chromosome ❑ Gene activated → copy of gene travels from cell nucleus to body of the cell where it serves as a template for building a protein molecule ❑ Proteins each serve a different function; how they work together is what creates a living organism ❑ Genetics and Social Development ◼ Genetic Variability – result of 3 phenomena: 1) the huge number of chromosome combinations that are possible during the formation of sperm and egg cells 2) the union of ovum with sperm as 23 chromosomes from a woman unite with 23 chromosomes from a man to form the zygote 3) crossing over, which occurs during cell division in the fertilized egg and involves the exchange of genes on homologous chromosomes Genetics and Social Development: Methods of Studying Genetic Contributions to Development Adoption Studies ◼ Compare adopted children to biological parents (genetic connection) and adoptive parents (environmental connection) ❑ Twin Studies ◼ Compare similarities between identical twins and fraternal twins ❑ ◼ ◼ Monozygotic twins – identical twins who are created when a single zygote splits in half and the two become distinct embryos with almost exactly the same genes Dizygotic twins – fraternal twins who develop from two different eggs fertilized by two different sperm, producing two different zygotes Genetics and Social Development: Methods of Studying Genetic Contributions to Development Twin Studies ◼ ❑ ❑ If monozygotic twins show more resemblance than fraternal twins, then assumed that trait is largely due to genes If resemblance is equal across two types of twins, the assumed that trait is largely influenced by environment What are the limitations of this design? Genetics and Social Development: Methods of Studying Genetic Contributions to Development ◼ Shared environment – A set of conditions or activities experienced by children raised in the same family ◼ Nonshared environment – A set of conditions or activities experienced by one child in a family but not shared with another child in the same family ◼ Identical twins may have more shared environments than fraternal twins ◼ Fraternal twins may have more nonshared environmental experiences than identical twins What are the implications for interpreting twin study results? Genetics and Social Development: Methods of Studying Genetic Contributions to Development Lessons learned from the Human Genome Project… ◼ ❑ ❑ Have mapped and sequenced about 20,000 protein-coding genes But, don’t know what all of these do or how they contribute to many human characteristics ❑ Most social behaviors are influenced by many genes and genetic effects are much smaller than previously thought ❑ Genes never work in isolation but always in combination with the environment Genetics and Social Development: Models of Genetic Influence ◼ Basic Model of Transmission → Single gene traits ❑ Allele – An alternate form of a gene; typically, a gene has two alleles, one inherited from the individual’s mother and one from the father ❑ Homozygous – Alleles for a particular trait from each parent are the same ◼ ❑ Individual exhibits trait carried by both alleles Heterozygous – Alleles for a particular trait from each parent are different ◼ ◼ ◼ May exhibit blend of each allele (incomplete dominance – e.g., intermediate skin color) May exhibit both traits (co-dominance – e.g., type AB blood) May exhibit trait of the dominant allele (dominant-recessive relationship between alleles) Genetics and Social Development: Models of Genetic Influence ◼ Interactions Among Genes ❑ Single pairs of alleles do not determine most characteristics of social development ❑ Most characteristics determined by interactions among many genes ◼ ❑ Helps explain why some traits influenced by genes do not run in families A single pair of alleles may influence more than one trait ◼ Modifier genes – Genes that exert their influence indirectly by affecting the expression of other genes Genetics and Social Development: Models of Genetic Influence ◼ Environment Influences Gene Expression ❑ ❑ Reaction Range – The range of possible developmental outcomes established by a person’s genotype in reaction to the environment in which development takes place Canalization – When the reaction range for a trait is extremely narrow and more intense environmental experience is needed to have an influence ◼ Example: Infant babbling Genetics and Social Development: Models of Genetic Influence Range of Reaction ◼ ◼ ◼ ◼ Gottesman, 1963 If all 3 children experience the same environment Child C will always outscore Child A and Child B Child B could achieve a higher score than Child C if he or she experienced a more socially enriched environment Child C has the widest reaction range (most influenced by the environment) Child A has the lowest and the most limited reaction range (least influenced by environment) Genetics and Social Development: Models of Genetic Influence Genetic Makeup Helps Shape the Environment ◼ Gene-Environment Correlation ❑ ❑ ❑ Passive – The environment created by parents with particular genetic characteristics encourages the expression of these tendencies in their children Evocative – People’s inherited tendencies evoke certain environmental responses Active or Niche picking – people’s genes encourage them to seek out experiences compatible with their inherited tendencies Genetics and Social Development: Models of Genetic Influence Gene-Environment Interaction (G x E) Model ◼ People in the same environment are affected differently depending on their genetic makeup. ❑ Example: children who are genetically more emotionally vulnerable are likely to be affected by family stress more than children who are emotionally robust Genetics and Social Development: Models of Genetic Influence Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., . . . Poulton, R. (2003). Influence of life stress on depression: Moderation by a polymorphism in the 5-HTT gene. Science, 301, 386–389. Reprinted with permission from AAAS Percentage of individuals meeting diagnostic criteria for depression at age 26, as a function of depressive genotype and number of stressful life events between ages 21 and 26 Genetics and Social Development: Models of Genetic Influence Gene-Environment Feedback Loops Gottlieb, G., & Lickliter, R. (2004). The various roles of animal models in understanding human development. Social Development, 13, 311–325. This material is reproduced with permission of John Wiley & Sons, Inc. Genes and environments are inextricably linked and operate in a mutually dependent fashion; it is impossible to treat them as truly separable Genetics and Social Development: Genetic Anomalies ◼ Turner syndrome – A pattern of abnormal reproductive organs and secondary sex characteristics caused by a lack of an X chromosome in females ◼ Fragile X syndrome – An area near the tip of the X chromosome is narrow and fragile due to a failure to condense during cell division; symptoms include physical, cognitive, and social problems; more common in males Williams syndrome – A pattern of unusually high sociability, empathy, sympathy, and prosocial behavior in children who lack the long arm of chromosome 7 ◼ ◼ ◼ Attention deficit/hyperactivity disorder (ADHD) – A disorder characterized by a persistent pattern of inattention and hyperactivity or impulsivity Autism spectrum disorder (ASD) – Disorder that begins in childhood, lasts a lifetime and disrupts social and communication skills Genetics and Social Development: Genetic Anomalies Genetic Counseling, Genetic Selection ◼ Sample cells from developing fetus to examine chromosomes Amniocentesis ❑ Chorionic villi sampling ❑ Ethical concerns? Genetics and Social Development: Genetic Anomalies Genetic Counseling, Genetic Selection ◼ Preventive genetic counseling – couples tested for defective genes then faced with decisions… ❑ ❑ ❑ Adoption Assisted reproductive technique – substitution of donor’s egg or sperm Gene therapy – inserting normal alleles into patients’ cells to compensate for defective alleles Ethical concerns? Temperament: Causes and Consequences ◼ Temperament – An individual’s typical mode of response including activity level, emotional intensity, and attention span; used particularly to describe infants’ and children’s behavior ◼ Thomas and Chess ❑ Difficult babies (10%) – slept and ate irregularly, became easily upset by new situations, and experienced extremes of fussiness and crying ❑ Easy babies (40%) -friendly, happy, and adaptable ❑ Slow-to-warm-up babies (15%) – low in activity level and tended to respond negatively to new stimuli at first but slowly adapted to new objects and novel experiences after repeated contact with them Temperament: Causes and Consequences Rothbart Broad dimensions Effortful control Attention control Scale definitions Inhibitory control The capacity to plan future action and to suppress inappropriate responses Perceptual sensitivity Detection or perceptual awareness of slight, low-intensity stimulation in the environment Low-intensity pleasure Pleasure derived from activities or stimuli involving low intensity, rate, complexity, novelty, and incongruity Affiliation Desire for warmth and closeness with others, independent of shyness or extraversion (in Adolescent Questionnaire only) The capacity to focus attention as well as to shift attention when desired Temperament: Causes and Consequences Rothbart Negative affectivity Frustration Negative affect related to interruption of ongoing tasks or goal blocking Fear Negative affect related to anticipation of distress Discomfort Negative affect related to sensory qualities of stimulation, including intensity, rate, or complexity of light, movement, sound, or texture Sadness Negative affect and lowered mood and energy related to exposure to suffering, disappointment, and object loss Soothability Rate of recovery from peak distress, excitement, or general arousal Temperament: Causes and Consequences Rothbart Extraversion-surgency Activity Level of gross motor activity including rate and extent of locomotion Low—shyness Behavioral inhibition to novelty and challenge, especially social High-intensity pleasure Pleasure derived from activities involving high intensity or novelty Smiling & laughter Positive affect in response to changes in stimulus intensity, rate, complexity, and incongruity Impulsivity Speed of response initiation Positive anticipation Positive excitement and anticipation for expected pleasurable activities Temperament: Causes and Consequences The Biological Basis of Temperament Genetic Factors ◼ Temperament may be at least in part genetically determined and genetic influences may become increasingly prominent through early childhood ◼ Most psychologists today consider temperament to be the result of both heredity and environment Temperament: Causes and Consequences The Biological Basis of Temperament Neurological Correlates ◼ Neurochemical molecules, such as epinephrine, dopamine, vasopressin, and oxytocin, seem to play a role ❑ Extraversion has been 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 ◼ Timid infants and children who were highly reactive to unfamiliar events showed more activation in the amygdala region of the brain in novel situations than did bold children who were low in reactivity Temperament: Causes and Consequences Early Evidence of Temperament ◼ Prenatal activity ◼ Newborn differences in distress and avoidance ◼ Infant differences in how much they smile at and approach social stimuli and expression of negative emotion ◼ Differences in effortful control by age 30 to 45 months – ability to inhibit, facilitate, make plans for, and detect errors in action Temperament: Causes and Consequences Correlates and Consequences of Temperament ◼ Children who are more irritable, difficult, impulsive, and emotional experience a higher rate of problems in later life ◼ Fearful, shy children → Internalizing problems ❑ ◼ Childhood behavior problem in which the behavior is directed at the self rather than others, including fear, anxiety, depression, loneliness, and withdrawal Poor effortful control → Externalizing problems ❑ childhood behavior problem in which the behavior is directed at others, including hitting, stealing, vandalizing, and lying What might contribute to these associations? Temperament: Causes and Consequences Correlates and Consequences of Temperament ◼ Children with difficult temperaments may find it more difficult to adapt to environmental demands ◼ Children with difficult temperaments may elicit more adverse reactions from other people ◼ Temperament may interact with conditions in the environment ◼ Associations between temperament and later problems depend on the temperament “package” the child comes with Concluding Thoughts ◼ Research supports the notion that babies are biologically prepared for social interactions (e.g., preference for faces and human voices) ◼ Evidence also suggests that the brain provides a foundation for social development (e.g., mirror neurons) and that the environment contributes to brain development (e.g., neuronal pruning, experience dependent and expectant processes) ◼ Genetic transmission also contributes to social development with several genes and interactions among them contributing to social behavior. In turn, the environment can influence genetic expression. ◼ Temperament, which has a biological basis, contributes to social development via differences in emotionality, activity level, and sociability. But again, the environment (e.g., parenting) can contribute to the likelihood of problems related to temperament. ◼ Bottom line: Biology and environment are constantly influenced by each other and working together to shape social development SchwabLearning.org ® A Parent’s Guide to Helping Kids With Learning Difficulties Temperament Scale Directions: Before beginning, take time to observe your child at home, at school, and with friends. Talk to other people who know him. Be sure to focus on all behaviors, not just those that seem problematic. After gathering information, rate your child on each of the nine traits. Place an X along the continuum where you believe he fits. Refer back to How Does Temperament Affect My Child’s Behavior? to review the descriptions, if necessary. Remember the whole scale represents a normal temperament range — high and low do not necessarily mean “dysfunctional.” Activity Level: amount of physical energy / Low Energy / High Energy AVERAGE Sensitivity: sensory threshold Low sensitivity ——–/—————————/——-/ / AVERAGE High Sensitivity Regularity: rhythm or predictable recurrence of daily activities or routines Low Predictability ——-/—————————/——-/ / AVERAGE High Predictability Approach/Withdrawal: initial reaction to new situations. Withdraws ——-/—————————/——-/ / AVERAGE Approaches Adaptability: length of time needed to adjust to new situations Slow to Adapt ——-/—————————/——-/ / – Adapts Easily AVERAGE Mood: general tendency toward a happy or unhappy demeanor. Negative ——-/—————————/——-/ / AVERAGE Positive Intensity: amount of energy put into responses. Less Responsive ——-/—————————/——-/ / — More Responsive AVERAGE Persistence: ability to stick with a task in spite of distractions or frustration. Low Persistence ——–/—————————/——-/ / AVERAGE High Persistence Distractibility: tendency to be sidetracked by outside noise or interruptions. Highly Distractible ——- ————————— ——– ©Schwab Learning 2003. Based on Temperament and Development, by A. Thomas and S. Chess, published in 1977 by Brunner/Mazel, New York.)
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