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Class 2 More on prenatal development and infant capacities at birth Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Life in the womb Normal gestation lasts between 37 and 43 weeks. It comprises 3 periods: -the germinal period (conception to implantation in the uterus, 8 to 10 days) -the embryonic period (implantation to ossification, end of 8th week) -the fetal period (9th week to birth). The fetus is responsive to its environment in new ways: is this where human psychology begins? Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Sensory capacities of the fetus Sensing motion, hearing, seeing, touching, tasting and smelling. The vestibular system in the middle ear starts to function at 5 months GA so the fetus can sense changes in the mother’s posture and can adapt to it. Fetuses respond to light after 26 weeks of gestation but vision is the slowest developing sense in infancy. Fetuses respond to touch around lips and cheeks by 8 weeks of gestation. By 14 weeks most of the body responds to touch. Fetus touches its own face from 10 -11 weeks (Hepper, 1995). Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Sensory capacities of the fetus By 15-16 weeks the fetus responds to the flavour of the amniotic fluid, swallowing more if it tastes sweet and less if it is bitter. The fetus learns about tastes and smells in utero: e.g. if the mother eats garlic during her pregnancy her newborn exhibits less of an aversion to garlic than newborns whose mothers did not eat garlic (Schaal et al., 2000). Newborns prefer the odor of their mothers at birth (Macfarlane, 1975). Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Listening in the womb The fetus responds to sound from 22-24 weeks of gestation. The sound level in the womb is around 75 decibels but louder sounds are produced by mother’s stomach and heartbeat. Of all the sounds the mother’s voice is heard best: it is heard from within and from outside. In fact infants prefer the voice of the mother when it is low-pass filtered (Fifer & Moon, 1995). The fetus can discriminate between different voices, speech sounds and languages, particularly with regard to pitch and rhythm (Lecanuet, Granier-Deferre & Busnel, 1995). Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Fetal movement The fetus is continually active in and reactive to its environment. This is fundamental for development. Within 8 weeks GA, the embryo becomes active. By the 15th week the fetus is capable of all mouvements observable in a newborn. By 4 months GA mothers can feel the fetus moving. Prenatal activity is crucial for normal limb development but also for brain circuitry. It plays a crucial role in establishing basic neuronal connections. As the fetus develops, its movements become organised into periods of activity and inactivity. At the end of gestation there are 4 fetal behavioral states: quiet sleep, active sleep, quiet awake and active awake. Handedness is observed from 10 weeks of gestation though hemispheric specialisation has not occured. Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Learning in the womb Learning to recognise the mother’s voice in utero (De Casper & Fifer, 1980) Neonates listened to either mother’s voice or other female voice telling the same story. They activated the recordings by increasing the amplitude of succion on a nipple. => infants accelerated their sucking to hear mother’s voice. Learning stories, poems and music (De Casper & Spence, 1986; Hepper, 1991). Learning the rhythms of the mother-tongue (Mehler; Lecanuet; Moon, Cooper & Fifer, 1993) Culture in the womb? What is culture? Culture is inseparable from communication. -a dynamically evolving set of beliefs, pratices and habits that unite people in feeling part of a ‘community’. The child lives within its culture before it is born through the cultural ‘habitus’ of the mother’s body movements, ways of speaking, singing and interacting with others. The fetus moves with the mother and hears the encultured voices of the mother and others in her community. It tastes and is nourished by the food and drink she consumes. The fetus ‘communicates’ with the culture-at-large through the family sub-culture. Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 The human newborn’s immaturity and the brain’s ‘readiness’ for culture Infants are physically and emotionally supported in each of their developmental acquisitions. e.g. finding the nipple for feeding. Mothering (parenting) pratices are both intuitive and culturally transmitted. Survival of the species depends on knowledge and skills that must be acquired (that are not innate), therefore the survival of the human species depends on distributed cultural know- how. Of all the species the human newborn’s brain will undergo most change after birth in response to environmental stimulation (but not any old stimulation!) The infant becomes a human brain through active participation in a world of shared meaning. Human newborns show communicative precocity. Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 An evolutionary hypothesis Bipedalism is considered by many as one of the main reason for altriciality. It probably caused the pelvis to change size and the birth canal to narrow. Fetuses then had to be born ‘prematurely’ to pass through the birth canal. As a result of bipedalism (tools use etc.) brains also grew larger. Dean Falk, a paleontologist/anthropologist’s perspective on motherese: the ‘putting the baby down’ hypothesis Human infants are not equiped to cling to their mothers like primate infants. So mothers had to put them down. Motherese and vocal interaction developed in order to maintain contact and to reassure infants. Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Development of the brain in utero Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 READY FOR CONVERSATION A Foetus at 8 weeks has organs formed for seeing, hearing, touching and speaking, before the brain is active. Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Development of the brain Basic operative units of brain activity: neuron. Neurons are made of axons and dentrites. The synapse is the tiny gap between axons and dendrites across which neurons communicate: via neurotransmitters that carry an electrical impulse across the synaptic gap. Billions of neurons become connected in an infinite variety of ways. Brain growth involves 1)increase in size and complexity of dentrites = synaptogenesis (prenatal development, infancy and adolescence), 2) increase in number of branches of axons = more complex neural circuits, 3) myelination (myelin = sheath of fatty cells that insulate axons) Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 Development of the brain T Social Development in Infancy (Dev 3) - University of Warsaw (WISP) Instructor: Maya Gratier - 2/11 June 2008 The CNS and the brain THe CNS is divided into 3 sections: 1) the spinal cord, 2) the brain stem and 3) the cerebral cortex. The brain stem controls elemetary reactions and vital functions. The brain stems and sub-cortical structures develop before the cerebral cortex and the most developed brain structures at birth. These are the parts that serve the newborns social and interpersonal skills The cortex is divided into 2 hemispheres, each divided into 4 lobes: occipital lobes specialized for vision, temporal lobes for hearing and speech, parietal lobes for spatial perception and frontal lobes for control and coordination (executive functions) (this is least mature at birth).
