Fall, 2005

HUMAN DEVELOPMENT 1 PSYCHOLOGY 3050:

Biological Bases of Cognitive Developement

Dr. Jamie Drover SN-3094, 864-8383 e-mail – [email protected]

Winter Semester, 2013

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Fall, 2005

Evolution and Cognitive Development



Evolution

: the process of change in gene frequencies in a population over many generations that in time, produces new species.

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Fall, 2005

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.

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Fall, 2005

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.

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Fall, 2005

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.

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Fall, 2005

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.

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Fall, 2005

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” 7

Fall, 2005

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.

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Fall, 2005

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.

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Fall, 2005

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 10

Fall, 2005

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) 11

Fall, 2005

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. 12

Fall, 2005

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. 13

Fall, 2005

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.

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Fall, 2005

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 15

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Fall, 2005

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 gene is obtained from the father, another is obtained from the mother.

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Fall, 2005

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.

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Fall, 2005

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.

Fall, 2005

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.

Fall, 2005

Developmental Systems Approach

 Hemispheric asymmetries are due to an interaction between genetically paced maturation and prenatal species-typical experience.

Fall, 2005

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 (1 st and second 2 nd ) are most easily acquired during childhood.

Overall, timing of perceptual experience is crucial.

Fall, 2005

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

Fall, 2005

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

Fall, 2005

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

Fall, 2005

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

Fall, 2005

Developmental Timing

• 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

Fall, 2005

Genotype-Environment Theory

 

Behavior genetics

: studies genetic effects on behavior and complex psychological characteristics such as intelligence and personality.

Scarr & McCartney: genes drive experience

Fall, 2005

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

Fall, 2005

Genotype-Environment Theory

 There are multiple levels of influence.

Genotype of parent Genotype of child Phenotype of child Rearing environment of child

Fall, 2005

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

Fall, 2005

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

Fall, 2005

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.

Fall, 2005

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.

Fall, 2005

Genotype-Environment Effects

 As children become more autonomous with age, the influence of genetic and environmental factors on individual differences changes.

Fall, 2005

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 36

Fall, 2005

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.

Fall, 2005

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.

Fall, 2005 39

Brain Development

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

Fall, 2005

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)

Fall, 2005

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.

Fall, 2005

Neuronal Development

Fall, 2005

Transmission from neuron to neuron

43 • • • • 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

Fall, 2005

Transmission from neuron to neuron

Fall, 2005

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.

Fall, 2005

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.

Fall, 2005

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.

Fall, 2005

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. 48

Fall, 2005

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.

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Fall, 2005

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

Fall, 2005

How Do Young Brains Get Hooked Up?

   Maurer et al. studied infants who were born with cataracts and had them removed at different points in life.

Those who had the cataracts removed within the first several months after birth displayed the typical pattern of visual development.

Those who had the cataract removed later showed poor visual development, and poor face processing.

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Fall, 2005

Selectionist Theories



Neural level

– neurons, dendrites, synapses are overproduced in early development

 

Those that are used survive, those that are not are lost (pruning) “Use it or lose it”



Pruning is important to later development

Fall, 2005

Greenough also proposed …

•

Experience-dependent processes

– Neural connections that reflect unique experiences • These experiences result in the alteration of neural connections. • So impoverished environments result in “pruning” through disuse • What determines the survival of synaptic connections is the principle of use.

– Those activated by sensory and motor experiences survive, the remainder are lost.

Fall, 2005

The Neocortex

  A multilayered sheet of neurons measuring 3-4 mm.

The part of the brain primarily associated with thinking.

Fall, 2005

The Neocortex

    Consists of two halves joined by the corpus callosum.

Primary Areas

receive info directly from the senses.

Or, they send instructions to body to muscles.

Secondary areas

integrate information and connect with other brain regions.

 Responsible for complex thought.

Fall, 2005

The Neocortex

Fall, 2005

The Neocortex

 The prefrontal lobes appear important for inhibition.

 A not B task

Fall, 2005

The Neocortex

 Diamond (1991) showed that children are increasingly able to inhibit their responses.

 May be related to development of the prefrontal cortex.

  There are also changes in brain structure and function that occur later in life.

Adolescents often display self-centeredness, emotional instability, increases in risk-taking, and seeking of novelty.

Fall, 2005

The Neocortex

   This time period is associated with changes in the frontal lobes (decrease in relative size, change in organization).

There are also changes in the distribution of neurotransmitters in the frontal cortex and the limbic system.

These changes may be adaptive to force adolescents to become independent from their parents.

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Fall, 2005

The Brain’s Plasticity

• • • •

Refers to the potential outcomes that are possible for a single neuron, bundles of neurons, or larger brain structure Capacity for change in structure or function Infant brain is only weakly specialized Use or disuse of neural circuitry determines plasticity

Fall, 2005

Neuronal Plasticity

   There is no plasticity on neuronal production.

There is plasticity in synapses as connections form throughout life.

 The formation of new synapses is based on experience.

Evidence comes from enrichment experiments.

Fall, 2005

Neuronal Plasticity

• Rats are raised in enriched or impoverished environments – Group rearing, platforms, objects vs. single rearing, bland environment • Enriched rats superior to deprived rats – Problem solving – Maze learning – Heavier cortex – larger neurons, more dendrites – 20% more synaptic connections 62

Fall, 2005

The Brain’s Plasticity

     Plasticity greater in infancy – brain not “set” - synaptic connections “up for grabs” over extended period of growth.

With some exceptions, recovery from brain injury more likely in children than adults.

Brain damage to language areas.

But the human brain is not entirely plastic, even in children. The effects can be reversed in brain areas that control general functioning.

Fall, 2005

The Brain’s Plasticity

   The plasticity of behavior and intelligence is attributed to the slow growth of the brain.

This means the brain is inefficient when we are young.

The plasticity afforded allows us to overcome early deprivation.