7. Genetics, Development, and Environmental Influences in Human Traits

Genotype

The genetic constitution of an individual, which interacts with the environment to produce the phenotype.

Phenotype

The observable characteristics of an individual resulting from the interaction of the genotype with the environment.

Dominant gene

A gene that requires only one copy to reveal its trait.

Recessive gene

A gene that requires two copies to reveal its trait.

Polygenic inheritance

Inheritance of traits that are determined by multiple genes.

Phenylketonuria (PKU)

A genetic disorder characterized by the inability to metabolize phenylalanine, leading to cognitive deficits.

Down Syndrome (Trisomy 21)

A genetic disorder caused by the presence of an extra 21st chromosome, resulting in low IQ and various physical and cognitive challenges.

Heritability

The proportion of a given behavior that is due to genetics rather than environmental factors.

Identical twins

Twins that result from the splitting of a single fertilized egg and share the same DNA.

Fraternal twins

Twins that result from the separate fertilization of two eggs and have different DNA.

Heritability coefficient

A measure of the degree of association between the traits of identical twins and fraternal twins.

Genetic disorders

Conditions caused by abnormalities in genes or chromosomes, with over 7000 known types.

Huntington's Disease

A genetic disorder caused by a dominant gene, leading to nervous system deterioration after the age of 40.

Cognitive variation

Differences in mental abilities such as IQ, language, and memory among individuals.

Behavioural variation

Differences in personality traits and behaviors among individuals.

Physical variation

Differences in physical traits such as hair color, eye color, and height among individuals.

Genetics

The study of heredity and the variation of inherited characteristics.

Twin studies

Research methods that compare the similarities between identical and fraternal twins to understand the influence of genetics and environment.

Natural variation

The differences found within a population, which can be attributed to genetic and environmental factors.

Abnormalities of sex chromosomes

Genetic conditions resulting from irregularities in the sex chromosomes, which can affect development and health.

Congenital defects

Physical abnormalities present at birth, which can be caused by genetic factors.

Environmental factors

External influences that can affect an individual's development and behavior.

Genetic-environment interaction

The interplay between genetic predispositions and environmental influences that shape an individual's traits.

Delayed language

A developmental issue where language acquisition is slower than expected.

Motor difficulties

Challenges in coordinating muscle movements for physical activities.

Behavioural genetics

The field that studies the influence of genetics and environment on behavior.

Correlations

The degree of association between the scores of twins on a given trait.

Adoption studies

Research that compares adopted children with their biological and adoptive families to assess genetic and environmental influences.

Zygotic stage

The first stage of development, lasting for the first 2 weeks after conception.

Embryonic stage

The second stage of development, occurring from weeks 3 to 8 after conception.

Foetal period

The final stage of development, spanning from weeks 9 to 40 after conception.

Teratogenic influences

Environmental factors that can cause malformations during embryonic or foetal development.

Generalizability

The extent to which findings from a study can be applied to broader populations.

Prenatal development

The process of development of the fetus during pregnancy.

Genetics + environment

The combined influence of genetic and environmental factors on behavior.

Shared environment

The environmental factors that are common to individuals, such as family upbringing.

Shared genetics

The genetic factors that are common to individuals, such as those shared by siblings.

Complex systems

Interconnected sets of genes and environmental factors that influence traits.

Behavioural outcomes

The observable behaviors that result from genetic and environmental interactions.

Structural development

The process of forming the physical structures of the body, such as limbs and organs, during embryonic development.

CNS development

The rapid development of the central nervous system that occurs during the fetal period.

Pathogens

Microorganisms that can cause disease and may affect fetal development.

Rubella

A viral infection that can lead to serious birth defects if contracted during pregnancy.

HIV

Human Immunodeficiency Virus, which can be transmitted from mother to child during pregnancy and affect development.

Thalidomide

A drug that caused numerous birth defects when taken during pregnancy.

Quinine

A medication for malaria that has been associated with deafness in infants when taken during pregnancy.

Aspirin

A medication that may lead to low birthweight, stillbirth, poor motor development, and lower IQ, although its effects are controversial.

Foetal Alcohol Syndrome

A condition resulting from alcohol consumption during pregnancy, leading to physical and cognitive impairments in the child.

Cognitive development

The progression of a child's ability to think and understand, which can be affected by teratogenic influences.

Moderate alcohol intake

Defined as 1 drink per day, which can cause minor physical and behavioral abnormalities but not full Foetal Alcohol Syndrome.

Heavy drinkers

Individuals consuming more than 5 drinks per day, who have a 30% chance of having children with Foetal Alcohol Syndrome.

Conceptual development

The process by which children learn to understand and categorize the world around them.

Category

A class of things or events in the world, such as humans, animals, and plants.

Concept

A mental representation of a class of things or events, reflecting our internal knowledge of categories.

Broad categories

General classifications that children form early in life, including people, animals (excluding plants), and inanimate objects.

Habituation-dishabituation paradigm

A research method used to study infants' ability to recognize and differentiate between stimuli.

Surprisal effect

The interest shown by infants when they encounter new stimuli after becoming bored with familiar ones.

Category hierarchies

The organization of categories into broader classes, indicating that children can differentiate between various groups.

Casual understanding

The basic comprehension that children develop regarding the relationships and differences between categories.

Perceptual similarity

Young infants appear to categorise on the basis of perceptual similarity.

Perceptual dimensions

Infants attend to a number of perceptual dimensions: colour, size, movement, part-whole relationships.

Basic level categories

Basic level categories acquired first - why? Generic term that covers important features shared by most instances of category.

Example of categorisation

e.g., cat → furry, four legs, pointed ears, long tail, meows.

Superordinate and subordinate categories

How do children learn superordinate and subordinate categories? Basic level provide a foundation; parents make use of this.

Causal relations

Understanding causal relations is crucial to forming many categories.

Understanding clouds

e.g., understanding that clouds are condensed water vapour explains rain.

Wugs and Gillies

4-5yo children told about two categories of monsters: Wugs (claws, spikes on tail, horns on head, armour on backs) and Gillies (wings, big ears, long tails, long toes).

Function of features

Children who were told function of features better at categorising.

Naïve psychology

We all have a naïve psychology of self and others.

Three concepts of understanding behavior

We use our understanding of three concepts to understand human behaviour: Desires, Beliefs, Action.

Theory of Mind

Theory of Mind: an organised understanding of how mental processes (intentions, emotions, beliefs, desires, perceptions) influence behaviour.

Development of Theory of Mind

The development of ToM takes a considerably long time.

Joint attention

Around 12 months of age children begin engaging in joint attention.

False belief task

Joint attention is a prerequisite to understanding the contents of others' minds.

Understanding actions and desires

Phillips et al. (2002) showed that 12-month-olds (but not 8-month-olds) understand that actions are linked to desires.

Subjective desires

Gopnik & Slaughter (1991) showed that 2yo understand that desires are subjective, even when another person's desire conflicts with their own.

Unexpected Location Task

A task where a child predicts where a character will look for an object based on their false belief.

Imaginary Companions

A very vivid imaginary character with which the child interacts during play and daily activities.

Social Contingency Play

Play that involves social interaction, such as 'peek-a-boo'.

Object Play

Play that involves manipulation of objects, such as building with Lego.

Language Play

Play that involves the use of language, such as babbling or rhymes.

Physical Play

Play that involves physical activities and movement.

Fantasy or Pretend Play

Play where children engage in imaginative scenarios and roles.

Empathy Development

The development of empathy is predicted by the understanding of theory of mind.

Communicative Development

Children's and adults' communicative development is related to their understanding of others' minds.

Developmental Disorders

Theory of mind is delayed or impaired in several developmental disorders.

Alcohol Effects on Unborn Babies

Alcohol can cause developmental issues in unborn babies, leading to various outcomes for affected children.

Categorization Decisions in Infants

Infants are likely to make categorization decisions based on their experiences and exposure.

Characteristics of Children with ICs

Children with imaginary companions often display unique personality traits and behaviors.

Prevalence of ICs

Up to 65% of children have an imaginary companion at one point in development.

Gender Differences in ICs

There are observed gender differences in the prevalence and nature of imaginary companions.

First Born and Only Children

Imaginary companions are most often found in first born and only children.

Research on ICs

Studies have shown that children with imaginary companions may have personality problems.

Invisible Friends (IF)

A type of imaginary companion that children create, often more common in Western cultures.

Personified Objects (POs)

Imaginary companions that are based on inanimate objects given human-like qualities.

Imaginative Children (IC)

Children who have imaginary companions and are reported by parents to be highly imaginative.

Non-Imaginative Children (NIC)

Children who do not have imaginary companions.

First Born Children

Children who are the eldest in their family, found to be 2.8 times more likely to have imaginary companions.

Gender Differences in IC

Girls are 1.7 times more likely to have imaginary companions compared to boys.

Cultural Differences in IC

Children in developing countries show lower rates of imaginary companions, approximately 21%.