HUMAN DEVELOPMENT 1 PSYCHOLOGY 3050: Biological Bases of Cognitive Developement

1. HUMAN DEVELOPMENT 1PSYCHOLOGY 3050:Biological Bases of Cognitive Developement Dr. Jamie Drover SN-3094, 864-8383 e-mail – jrdrover@mun.ca Winter Semester, 2013

2. Evolution and Cognitive Development • Evolution: the process of change in gene frequencies in a population over many generations that in time, produces new species.

3. Evolution and Cognitive Development • Based on natural selection. • Members of a species possess genetic variation. • Environmental conditions allow some species members to survive and reproduce. • Their traits will be passed on, i.e., reproductive fitness.

4. Evolution and Cognitive Development • Evolution provides a framework for interpreting all aspects of behavior and development. • It explains the how and why aspects of behavior and development. • How: natural selection • Why: it’s adaptive • Evolutionary Developmental Psychology: Explains human development through evolutionary theory and provide answers about adaptive fit to environment.

5. Evolutionary Psychology • Cosmides and Tooby (1976) believe that natural selection operates on the cognitive level. • Information-processing programs evolved cognitive abilities to solve specific problems. • How to communicate, recognize faces • Cognitive processes develop and infants and children face different problems than adults.

6. Evolutionary Psychology • We evolved domain-specific mechanisms to deal with specific aspects of the environment (face recognition, language). • Note that domain-general mechanisms also evolved due to natural selection. • Executive function: ability to inhibit thoughts and actions.

7. Evolutionary Psychology • There are constraints (limitations) on development • Constraints enable (promote) learning • Infants born into a “chaotic” environment • Too much stimulation would inhibit (or delay) learning • Instead infants and children are constrained to process only some information in core domains (e.g., language) • Can’t /don’t process everything; focus on “essentials”

8. Evolutionary Psychology • Geary (2005) believes that we evolved a set of domain-specific modules that develop as children engage their physical and social worlds. • There are overarching social and ecological domains with more specific domains (see Figure 2-1). • Despite these domain-specific modules, human cognition is very flexible.

9. Evolutionary Psychology • We did not evolve highly specific approaches to problems but genes and cognitive mechanisms that are highly adaptive. • These mechanisms become more specific and finely tunes during development due to experience.

10. Why does it take us so long to grow up? • Humans have an extended juvenile period • Longer than for any primate species • Provides the time needed to process and master complex environments, provides “flexible cognition”. • Long “apprenticeship” to learn about a broad range of environments • Requires a large brain

11. Evolutionary Psychology • According to Geary (1995), we have two broad types of cognitive abilities. • Biologically Primary Abilities: Selected for by evolution (E.g., language) • Biologically Secondary Abilities: Cultural inventions (E.g., reading)

12. Models of Gene-Environment Interaction • Developmentalists believe that development is the result of an interaction between genetic/biological factors and environmental/experiential factors. • the child is an active agent in his/her development • development proceeds through the bidirectional effect of structure and function • context is as important as one’s genes.

13. Developmental Systems Approach • Development occurs within a system of interacting levels. • Our development is based on epigenesis. • Development is characterized by increasing complexity of organization (the emergence of improved structures, functions, and abilities) at all levels of the system. This arises as a result of the interaction of all components of the system. • Based on the bidirectional interaction of genes, RNA, proteins, neurons, etc. with the environment.

14. Developmental Systems Approach • Epigenetic phenomena do not involve changes to the DNA code. • But it does involve change in the things that DNA influences • RNA, proteins, cells, neurons, neurotransmitters.

15. Developmental Systems Approach • Can’t understand development by looking at simple genetic or environmental effects • Essentially dynamic systems approach applied to development. • New structures and functions emerge through self-organization through bidirectional interactions of the elements at various levels. • Implies plasticity in development

17. Developmental Systems Approach • Research has indicated that there is a relationship between breasfeeding and later IQ. • This may be due to essential fatty acids that exist in breastmilk. • Caspi et al (2007) identified several variants of genes that process these fatty acids. • One genes is obtained from the father, another is obtained from the mother.

18. Developmental Systems Approach • Children who are CC or CG and were breastfed as infants had higher IQ than children with the same alleles but were not breastfed. • Children with a third version of the genes (GG) showed no effect on from being breastfed or bottle-fed. • The benefits of breastfeeding for IQ are influenced by combination of alleles that influence how fatty acids are processed.

19. Developmental Systems Approach • Why do species members develop in the species typical pattern? • We inherit species-typical genes and a species typical environment (see duck example, p 42). • Behavior is influenced by subtle aspects of the environment.

20. Developmental Systems Approach • Humans develop in species-typical environments (prenatal and postnatal) • Experience directs us in species-typical ways. • E.g., Development of hemispheric asymmetries. • May be due to the timing of the nature of prenatal auditory experiences (Turkewitz, 1993). • Exposed to socially important sounds when the left hemisphere of the brains is hitting a growth spurt.

21. Developmental Systems Approach • Hemispheric asymmetries are due to an interaction between genetically paced maturation and prenatal species-typical experience.

22. Developmental Timing • Sensitive Period: A time in development when a skill or ability is most easily acquired. • If the required experience occurs outside this period, it will not be easily acquired (or not acquired at all). • Language (1st and second 2nd) are most easily acquired during childhood. • Overall, timing of perceptual experience is crucial.

23. Developmental Timing • Too much early stimulation is not always good: • e.g., In vertebrates, vision develops more slowly than hearing • Lickliter (1990) suggested that slower vision allows hearing to develop without competition • Gave bobwhite quail pre-hatching visual experience • Cut a window in shell – chicks could see • Unnatural – normally they only hear

24. Developmental Timing • Tested post-hatching on call of quail vs chicken • No early vision – preferred quail call • Early vision – no preference for quail or chicken, but showed better visual discrimination

25. Developmental Timing Is there a possibility of sensory over-stimulation? • What about parents providing extra stimulation to infants? • Is it an advantage or a disadvantage for development? • Question has not been properly evaluated

26. Developmental Timing • Premature infants may experience deficits due too much sensory exposure (Als, 1995). • May lead to enhanced performance in some domains at the expense of functioning in others. • Could have an adverse effect on brain development

27. DevelopmentalTiming • Could over-stimulation require them to process info from the postnatal environment before they are “ready” • Could this have an adverse effect on brain development? • Some extra stimulation is needed to ensure life and health • These are important and still controversial issues

28. Genotype-Environment Theory • Behavior genetics: studies genetic effects on behavior and complex psychological characteristics such as intelligence and personality. • Scarr & McCartney: genes drive experience

29. Genotype-Environment Theory • A child’s inherited characteristics influence which environments he/she encounters and the type of experiences he/she has, which in turn influences his/her development • “niche picking” • Parents are also in the loop: • Their genes influence the type of environment they feel comfortable in and the genotype of the children

30. Genotype-Environment Theory Genotype of parent Genotype of child • There are multiple levels of influence. Phenotype of child Rearing environment of child

31. Genotype-Environment Theory • There are three types of genotype-environment effects that influence development. • Passive effects: • Parents provide genes and environment • Effects can’t be separated • Effects lessen with age

32. Genotype-Environment Theory • Evocative effects: • Child’s characteristics (e.g., temperament) elicit reactions from others • Effects constant with age • Active effects: • Child seeks out environments consistent with genotype • Effect increases with age as child becomes more independent

33. Genotype-Environment Effects • Parents’ environmental influence on children should be greatest during early childhood. • Scarr and Weinberg (1978) found that there was a moderate correlation between adopted siblings’ IQs. • The correlation for between adopted siblings’ IQ at adolescence is 0. • This finding is likely because passive genotype-environment effects reflected by the environment provided by parents decrease with age.

34. Genotype-Environment Effects • Active genotype-environment effects increase with age. • Do genes cause intelligence? • Genes serve to select “appropriate environments”, but experience is responsible for crafting intellect. • Genetic and environmental effects are dynamic, having different effects on intelligence at different points in time.

35. Genotype-Environment Effects • As children become more autonomous with age, the influence of genetic and environmental factors on individual differences changes.

36. Good enough parents? • Ordinary differences between normal families have little effect on child development • Strong influence of gene and environment effects – parenting has little consequence • Children around the world become productive members of society in spite of a wide range of parenting practices

37. Good enough parents? • Children don’t need perfect parents, just “good enough” parents. • Children who lack the opportunities and experiences associated with the dominant culture will show detriments. • Research on “resilient” children shows support for Scarr’s position.

38. Development of the Brain • The human brain provides amazing flexibility and diversity. • Has the same basic structures as other mammals but has led to mathematics, physics, art, and language. • Controls all aspects of behavior, from respiration, to digestion, to learning, and our most advanced forms of cognition.

39. Brain Development Human adult brain:1400 g; 2% of body weight Newborn brain: 350 g; 10% of body weight(infants are “top heavy”) Adult Newborn Infant and adult brains appear similar, but the infant’s is extremely immature in underlying neurological structure and function.

40. Brain Development • The newborn brain is underdeveloped. • Cannot control coordinated movement nor perform characteristic mental operations. • Our knowledge of brain development and its relation to cognition has increased thanks to neuroimaging techniques. • EEG, PET, SPECT, and fMRI (p. 52)

41. Neuronal Development • The nervous system communicates using electrical and chemical signals transmitted from one neuron to another. • The mature brain contains between 10 billion to 100 billion neurons. • Each is connected to hundreds or thousands of others at synapses. • The space between the axon of one neuron and the dendrites of another. Where chemical messages are sent/received.

42. Neuronal Development

43. Transmission from neuron to neuron • Impulses received by dendrites are conducted to the cell body where they travel down the axon to the end terminals • Neurotransmitters (e.g., serotonin, dopamine, acetylcholine) are released from synaptic vesicles • Travel across synaptic cleft (synapse) • Activate adjacent dendrites

44. Transmission from neuron to neuron

45. Proliferation, Migration, and Differentiation • Proliferation: cell division by mitosis. Occurs early in development. • Migration: The cells move to their permanent position. • Faulty migration may be associated with disorders (schizophrenia, FAS). • Differentiation: Neurons grow, produce dendrites, and extend their axons.

46. Synaptogenesis and Selective Cell Death • The process of synapse formation. • Rate is greatest in early pre- and post-natal months. • Peak varies for different brain parts. • Pruning begins late in the prenatal period with selective cell death. • Occurs at different rates for different brain areas.

47. Rise and Decline in Neural Development • Brain metabolism follows a similar pattern. • Peaking to a rate that 1.5 times the adult rate at 4 and 5 years of age. • Adult levels are reached at about age 9. • There are also age-related changes in neurotransmitters. • Increases early in life, followed by subsequent decreases.

48. Rise and Decline in Neural Development • This hypermetabolism (around the preschool years) may be necessary for the rapid learning that occurs early in life. • Hypermetabolism, large number of synapses, and increases in neurotransmitters may afford platicity.

49. How Do Young Brains Get Hooked Up? • Previously, it was thought that genes dictate the formation, migration, and differentiation of neurons, and experience “fine-tuned” the brain. • Now there is a greater emphasis on postnatal experience.

50. How Do Young Brains Get Hooked Up? • Greenough (1980s): Brain development is an extended process strongly influenced by postnatal experience • Specific experiences produce neural activity that in turn determine which of the excess synapses will survive • Nervous system prepared by evolution to expect certain types of stimulation (e.g., patterned light, moving objects) • These experiences form and maintain synapses • Experience-expectant processes • Certain functions (e.g., visual acuity) will develop for those who have the experience – if not, the connections are pruned