the genetics of behavior are we nature or nurture?
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The Genetics of BehaviorThe Genetics of Behavior
Are we nature or nurture?
Are we nature or nurture?
Two basic viewsTwo basic views
Nativists
Empiricists
Nativists
Empiricists
Emphasize genes and inborn characteristics
Emphasize learning and experience
Evolutionary PsychologyEvolutionary Psychology
Emphasizes evolutionary mechanisms that may help explain human commonalities in; Cognition, development, emotion,
social practices and other behavior.
Emphasizes evolutionary mechanisms that may help explain human commonalities in; Cognition, development, emotion,
social practices and other behavior.
Behavioral GeneticsBehavioral Genetics
An interdisciplinary field of study concerned with the genetic basis of behavior and personality.
An interdisciplinary field of study concerned with the genetic basis of behavior and personality.
An UnderstandingAn Understanding
All scientists understand there is an interaction between heredity and environment.
Set point - a genetically influenced weight control mechanism vs. obesity in the US.
All scientists understand there is an interaction between heredity and environment.
Set point - a genetically influenced weight control mechanism vs. obesity in the US.
The Secrets of GenesThe Secrets of Genes
Genes - are the basic units of heredity located on chromosomes which contain threadlike strands of DNA.
Egg and Sperm contain 23 chromosomes each.
Creating the genome
Genes - are the basic units of heredity located on chromosomes which contain threadlike strands of DNA.
Egg and Sperm contain 23 chromosomes each.
Creating the genome
Genome and what it meansGenome and what it means
After conception each cell has 23 pairs of chromosomes. (46)
Most traits depend on more than one gene pair.
After conception each cell has 23 pairs of chromosomes. (46)
Most traits depend on more than one gene pair.
How are traits studied?How are traits studied?
Linkage studies - look for patterns of inheritance of genetic markers in large families.
A genetic marker is a segment of DNA that varies among individuals.
Linkage studies - look for patterns of inheritance of genetic markers in large families.
A genetic marker is a segment of DNA that varies among individuals.
The Genetics of SimilarityThe Genetics of Similarity
Evolution is a change in gene frequencies within a population over many generations. (mutation)
Natural Selection is a process in which individuals adapt to a particular environment and survive.
Evolution is a change in gene frequencies within a population over many generations. (mutation)
Natural Selection is a process in which individuals adapt to a particular environment and survive.
Evolutionary PsychologistsEvolutionary Psychologists
They look to the prehistoric record to draw inferences about behavior that solved survival problems
Because of evolutionary history some qualities are universal…
They look to the prehistoric record to draw inferences about behavior that solved survival problems
Because of evolutionary history some qualities are universal…
Evolutionary PsychologistsEvolutionary Psychologists
Universal qualities are.1. Reflexes2. Attraction to novelty3. A desire to explore and manipulate
objects4. An impulse to play and fool around5. Basic mental skills
Universal qualities are.1. Reflexes2. Attraction to novelty3. A desire to explore and manipulate
objects4. An impulse to play and fool around5. Basic mental skills
Our Human HeritageOur Human Heritage
The origins of perception1. Sensation - the detection of physical
energy emitted or reflected by physical objects.
2. Perception - the process by which the brain organizes and interprets sensory information
The origins of perception1. Sensation - the detection of physical
energy emitted or reflected by physical objects.
2. Perception - the process by which the brain organizes and interprets sensory information
Our Human HeritageOur Human Heritage
3. Some abilities develop from certain experiences at certain times.
4. Complex features are processed by specialized detectors
5. Inborn perceptual abilities include…1. Startle reflex 3. Voice recognition2. Audio location 4. Discrimination of
smells
3. Some abilities develop from certain experiences at certain times.
4. Complex features are processed by specialized detectors
5. Inborn perceptual abilities include…1. Startle reflex 3. Voice recognition2. Audio location 4. Discrimination of
smells
The Face of EmotionThe Face of Emotion
Some expressions are universal and present from birth
Universal facial expressions function in communication.
Some expressions are universal and present from birth
Universal facial expressions function in communication.
Sociability and AttachmentSociability and Attachment
Synchrony and sociability Newborns are sociable from birth They pay attention to human faces
and show synchrony Attachment - the emotional tie that
children and their caregivers feel toward each other…
Synchrony and sociability Newborns are sociable from birth They pay attention to human faces
and show synchrony Attachment - the emotional tie that
children and their caregivers feel toward each other…
Sociability and AttachmentSociability and Attachment
Attachments cont’d Contact comfort which is the innate
pleasure derived from close physical contact.
Infants who do not develop secure attachments may develop emotional and physical problems.
Attachments cont’d Contact comfort which is the innate
pleasure derived from close physical contact.
Infants who do not develop secure attachments may develop emotional and physical problems.
The Capacity for LanguageThe Capacity for Language
Language is a system for combining meaningless elements into utterances that convey meaning. A child’s vocabulary increases at a
rapid rate.
Language is a system for combining meaningless elements into utterances that convey meaning. A child’s vocabulary increases at a
rapid rate.
Language DevelopmentLanguage Development
Requires the mastering of a complex set of rules including: Surface structure - the way a
sentence is actually spoken Deep structure - the meaning inferred
by a sentence Syntax - the rules of grammar
Requires the mastering of a complex set of rules including: Surface structure - the way a
sentence is actually spoken Deep structure - the meaning inferred
by a sentence Syntax - the rules of grammar
Language DevelopmentLanguage Development
Children do not simply imitate adults They are able to perceive deep
structure Noam Chomsky theorized that we
have a biologically based “language acquisition device” that aids in language development.
Children do not simply imitate adults They are able to perceive deep
structure Noam Chomsky theorized that we
have a biologically based “language acquisition device” that aids in language development.
Chomsky’s ExamplesChomsky’s Examples Children of
different cultures go through similar stages of linguistic development
Children of different cultures go through similar stages of linguistic development
Children combine words in ways that adults never would
Adults do not consistently correct their children’s syntax yet they learn to speak or sign correctly.
Children combine words in ways that adults never would
Adults do not consistently correct their children’s syntax yet they learn to speak or sign correctly.
Chomsky’s ExamplesChomsky’s Examples
Even children who are profoundly retarded acquire language.
Even children who are profoundly retarded acquire language.
Infants as young as 7 months can derive simple linguistic rules from a string of sounds.
Infants as young as 7 months can derive simple linguistic rules from a string of sounds.
Does Nurture Play a Role?Does Nurture Play a Role?
Imitation does play a role because parents correct the child’s ungrammatical sentence.
There appears to be a window of opportunity to learn language.
Imitation does play a role because parents correct the child’s ungrammatical sentence.
There appears to be a window of opportunity to learn language.
Evolution, Courtship and Mating
Evolution, Courtship and Mating
Sociobiology - an interdisciplinary field that emphasizes evolutionary explanations of social behavior in animals.
The view is that nature has selected psychological traits and social customs that promote propagation.
Sociobiology - an interdisciplinary field that emphasizes evolutionary explanations of social behavior in animals.
The view is that nature has selected psychological traits and social customs that promote propagation.
Evolution, Courtship, and Mating
Evolution, Courtship, and Mating
Sociobiologists argue that males and females have evolved different mating strategies. Males to inseminate as many females as
possible and females be more selective. As a result, males are thought to be more
promiscuous and drawn to sexual novelty, females are more interested in stability.
Sociobiologists argue that males and females have evolved different mating strategies. Males to inseminate as many females as
possible and females be more selective. As a result, males are thought to be more
promiscuous and drawn to sexual novelty, females are more interested in stability.
Sociobiology vs. EvolutionarySociobiology vs. Evolutionary Sociobiologists tend to argue by
analogy to nonhuman animals. Evolutionary biologists recognize these are simplistic and misleading.
Critics argue that evolutionary explanations are based on stereotype of gender. Theories are also nonfalsifiable.
Sociobiologists tend to argue by analogy to nonhuman animals. Evolutionary biologists recognize these are simplistic and misleading.
Critics argue that evolutionary explanations are based on stereotype of gender. Theories are also nonfalsifiable.
The Genetics of DifferenceThe Genetics of Difference
Heritability - is the statistical estimate of the proportion of the total variance in some trait that is attributable to genetic differences among individuals within the group…
Heritability - is the statistical estimate of the proportion of the total variance in some trait that is attributable to genetic differences among individuals within the group…
The Genetics of DifferenceThe Genetics of Difference1. An estimate of heritability applies only
to a particular group living in an particular environment.
2. Heritability estimates do not apply to individuals, only to variations within a group.
3. Even highly heritable traits can be modified by the environment.
1. An estimate of heritability applies only to a particular group living in an particular environment.
2. Heritability estimates do not apply to individuals, only to variations within a group.
3. Even highly heritable traits can be modified by the environment.
Computing HeritabilityComputing Heritability
Research methods are used in an attempt to infer heritability by studying people whose degree of genetic similarity is know. Adopted children share half their
genes but not environments with birth parents.
Research methods are used in an attempt to infer heritability by studying people whose degree of genetic similarity is know. Adopted children share half their
genes but not environments with birth parents.
Computing HeritabilityComputing Heritability
Identical (monozygotic) twins develop when a fertilized egg divides into two parts.
Fraternal (dizygotic) twins develop from two separate eggs fertilized by different sperm.
Identical twins raised apart from each other are of special interest because they have identical genes but a different environment.
Identical (monozygotic) twins develop when a fertilized egg divides into two parts.
Fraternal (dizygotic) twins develop from two separate eggs fertilized by different sperm.
Identical twins raised apart from each other are of special interest because they have identical genes but a different environment.
Heritability and IntelligenceHeritability and Intelligence
Intelligence quotient (IQ) - is a measure of intelligence originally computed by dividing a person’s mental age by his or her chronological age multiplied by 100
Currently it is norms based.
Intelligence quotient (IQ) - is a measure of intelligence originally computed by dividing a person’s mental age by his or her chronological age multiplied by 100
Currently it is norms based.
Genes and Individual Differences
Genes and Individual Differences
IQ scores are highly heritable with estimates averaging around .50 in children and .60 to .80 in adults.
Scores of identical twins are always more highly correlated than those of fraternal twins.
Scores with adopted children correlate higher with birth parents vs. adoptive parents.
IQ scores are highly heritable with estimates averaging around .50 in children and .60 to .80 in adults.
Scores of identical twins are always more highly correlated than those of fraternal twins.
Scores with adopted children correlate higher with birth parents vs. adoptive parents.
The Question of Group Difference
The Question of Group Difference
Race differences are controversial Asians as a group score higher than
whites who score higher than African Americans.
Some theorists have confused intra-group findings with inter-group.
Race differences are controversial Asians as a group score higher than
whites who score higher than African Americans.
Some theorists have confused intra-group findings with inter-group.
The Question of Group Difference
The Question of Group Difference
Minority children tend to have access to fewer educational and material resources.
Well designed studies have failed to reveal genetic differences.
Minority children tend to have access to fewer educational and material resources.
Well designed studies have failed to reveal genetic differences.
Genes and PersonalityGenes and Personality
Temperaments - physiological dispositions to respond to the environment in certain ways; present in infancy and are assumed to be innate.
Temperaments - physiological dispositions to respond to the environment in certain ways; present in infancy and are assumed to be innate.
Heredity and TemperamentHeredity and Temperament
Differences in children’s temperaments appear early in childhood.
Temperaments tend to remain stable throughout childhood.
Differences in children’s temperaments appear early in childhood.
Temperaments tend to remain stable throughout childhood.
Heredity and TraitsHeredity and Traits
A trait is a characteristic of an individual, describing a habitual way of behaving, thinking and feeling.
A trait is a characteristic of an individual, describing a habitual way of behaving, thinking and feeling.
Factor analysis - a statistical method for analyzing the inter-correlations among different measures now applied to traits.
Factor analysis - a statistical method for analyzing the inter-correlations among different measures now applied to traits.
Clusters of measures or scores that are highly correlated are assumed to measure the same underlying trait or ability.
Clusters of measures or scores that are highly correlated are assumed to measure the same underlying trait or ability.
Big Five FactorsBig Five Factors
Introversion vs. extroversion Neuroticism or negative
emotionality Agreeableness Conscientiousness openness
Introversion vs. extroversion Neuroticism or negative
emotionality Agreeableness Conscientiousness openness
Why are genes not everything?
Why are genes not everything?
Not all traits are equally heritable or unaffected by shared environments
Some studies may underestimate the impact of the environment
Even traits that are highly heritable are not rigidly fixed and can be modified by experience.
Not all traits are equally heritable or unaffected by shared environments
Some studies may underestimate the impact of the environment
Even traits that are highly heritable are not rigidly fixed and can be modified by experience.