Developmental Psychology Overview

Differential psychology

Between person differences (i.e. people differ on attributes we can measure such as height)

Identifying stable patterns to compare individuals

Two disciplines of scientific psychology

Experiments: experimental psychologist manipulate conditions to see what happens

Correlations: correlational psychologist measure free standing patterns of nature that we cannot directly control

-       Both fail to acknowledge the impact the other has on their findings

Kinds of differences

Demographic status = age, sex, marital status, religious affiliation, political views

Lifestyle factors = diet, exercise, alcohol consumption

Experiences and upbringing = wealth, educational opportunities

Psychological attributes = motivation, goals, risk tolerance, gender identity, sexuality 

Psychological attributes

Differences create ‘noise’ or error in psychology experiments, this is domain – specific i.e. rarely all error not just noise

Statistically this is called variance – differences that develop over time

Traits

-       A characteristic that can produce a particular kind of behaviour

-       Psychological traits are assumed to…

o   Lie within individuals

o   Distinguish among individuals

o   Stable over time

Intelligence

-       The way we can understand and obtain knowledge

Personality

-       The combinations of characteristics that make us unique

Variation differences

-       Differences in personality and intelligence predict life outcomes (if you are more intelligent you are more likely to do well in school)

-       These relationships are not pre-determined, our traits are not our fate

Difficulties is measuring

-       Cannot directly observe many of the characteristics we are interested in

-       Difficult to find consensus on defining the trait (not everyone agrees)

Personality and intelligence

Classic hierarchy model – mid blobs are obituary depending on test stricture, could create more layers. Arrows suggest that variation in ‘g’ causes variation in underlying abilities

Pervasive idea – different types of intelligence e.g. verbal, emotional etc

Fluid intelligence

-       Biologically fixed cognitive capacities, can be applied to anything

-       Uses figural tests

Crystallised intelligence

-       Acquisition of knowledge and procedural skills

-       Uses verbal tests

Personality

-       An individual’s characteristic style of thinking, behaving, and feeling

-       There is little agreement as it incorporates lots of qualitatively difference elements

Similarity and differences

-       Both are heritable, develop over time but remain stable cross sectionally

-       People take an active role (consciously or unconsciously) in their own personality development, constrained by environment

-       Typical performance – what you do when you are not under pressure

-       Maximal performance – what you do when under maximum pressure

How are tests used

In research:

-       Description

-       Prediction

-       Explanation

In practice

-       Selection

-       Diagnosis

-       Classification (are they part of a certain group)

How traits develop

Development = a property decreasing or increasing, or the emergence of something new over time

Genetics

Genetic potential of both parents being passed to offspring

Dominant = traits are expressed if the relevant gene is inherited from at least one parent

Recessive = traits are expressed only if the gene is inherited from both parents

Polygenic = more than one gene contributes to a trait

Pleiotropic = one gene can influence two or more unrelated traits

History and measurement

-       Although people have some background they all differ from each other in terms of psychological differences

-       Early personality psychologists developed the lexical hypothesis and the idea that personality is encoded in language through traits

Eugenics

-       That humans can be improved through selective breeding

Negative eugenics = discouraging or stopping reproduction in people with undesirable traits

Positive eugenics = encouraging increased reproduction in people with superior traits

-       Based on flawed / oversimplified understanding of genetics

Psychological constructs

-       Not directly observable (laten variables)

-       We observe patterns of behaviour or performance (observed variable) and make assumptions about hidden psychological characteristics that could be causing them

Basic measurement

-       Measurement typically requires `ground truth’ or real fixed quantity (e.g. height) that we can get measurement units from (e.g. cm)

-       These often use ratio scales which have scalar units starts at 0 (total absence)

-       Each unit spans the same amount e.g. 1cm->2cm is the same as 35cm->36cm

-       Our measurement should be consistent over time

-       After a certain point height measurements should be consistent (height does not change with context)

Error in measurement

-       Difference between the observed value and the ‘true’ value

-       Operationalising height using a ruler = small amount of error

-       Bias is anything that systematically distorts how accurately a test captures it’s target construct

Inferences about results

-       Hight is measured is never changing but interpretation is

-       160cm is ‘short’ for a man but ‘typical’ for a woman  

Reliability = how constant is our measurement

Validity = does our test measure what it is supposed to

Correlation = measure of association between two variables

Personality of measurement

A priori = creating sub tests within a test

A posteriori = factor analysis (measurement of association between many variables i.e. patterns of correlations within a test)

Personality traits

-       A persons ongoing adaptions of capacities to the social and physical demands of the surrounding environment

Personality ‘type’ models

Central tenet = people can be organised into discrete, discontinuous categories

Dynamic = traits only have modest correlations with behaviour

Interactionist perspective = personality traits reflect stable patterns of corresponding personality ‘states’ (behaviour is the product of trait environment interactions)

Big five / five factor model

-       Openness to experience

-       Conscientiousness

-       Extraversion

-       Agreeableness

-       Emotional stability / neuroticism

Lots missing…

-       Antisocial behaviour

-       Social dominance, competition, ambition

-       Morality, spirituality, religiosity

Why does it work?

-       personality influences our behaviours and life choices

-       Despite cloudy definitions they are psychologically relevant

What are ABCD’s

Affect; what we feel

Behaviour; what we do

Cognition; what we think

Desire; what we want

How do we measure personality

Personality inventories = self or other reports of the extn tot which statement =s or adjectives apply to respondents

Projective techniques = free from reactions to ambiguous situations or stimuli (reaction / responses interpreted by test administrator)

Empirically designed objective tests

-       Match groups differing in some crucial way in ither factors (e.g. good pilot)

-       Administer tests to both groups

-       Identify items that distinguish the sub group

Limitations of questionnaire measures:

-       People can easily ‘fake good’

-       People can often lack insight to how others see them

-       Difficult o wrote items interpreted one way

Advantages:

-       Information breadth (we are the best witnesses)

-       Practicality

-       Motivation to report (we are all interested in ourselves)

Self-presentation bias

-       Modified personality items to be more neutral e.g. “make plans and sticks to them” -> “avoid departing from a plan once I have made one”

Measurement of intelligence

IQ = a score on a specific test, typically follows a normal distribution

Cognitive ability = used non systematically to either refer to intelligence or to similar cognitive constructs e.g. working memory

Vocabulary = relations among words, similarities, opposites

Identifying sequence progressions = numbers, letters, diagrams

Short term and working memory = lists of numbers, unrelated words, keeping track of multiple tasks

Speed of processing = identifying or coding symbol, reaction time

Disadvantages of intelligence tests

-       Artificial, very limited context, low real world fidelity

-       No time to evaluate, extremely fast paced

-       Testing situations re often intimidating

The Flynn effect

The secular rise in IQ scores – since they were developed, population average scores have gone up steadily

-       If this were ‘real’; WW1 soldiers would be considered intellectually disabled today

Development of differences

-       People differ from each other in varied ways throughout their lives (differ in rates and directions of development of these differences)

-       We ned to establish whether individual differences are stable

-       To identify we need data (childhood/adulthood intelligent scores)

-       Collect a good sample (must represent the whole relevant population)

-       Identify an appropriate research design

Cross sectional design = asses a group of 20 year olds and a group of 80 year olds and compare

Advantages

-       Much faster and cheaper

-       Fewer concerns about drop outs

Disadvantages

-       Can evaluate prior influences on individual differences

-       Development is change, cant evaluate directly

-       Cohort effect (millennial vs gen z)

Longitudinal design = assess a group of 20 year olds once, then again 4 years later then again 4 years later and so on

Advantages

-       Actually measures change and differences in individuals

-       Can evaluate prior influences

Disadvantages

-       limited to one cohort typically

-       Some participants drop out

-       Age and time of measuring effects are tangles

Population representation

-       It is rarely practical to sample the whole population

-       Bigger is usually better (law of large numbers)

-       Participating in studies is usually voluntary and subject to selection bias (not everyone is willing)

Kinds of change

Quantitative = implies a simple difference in magnitude, but with the same mechanisms. Requires a common measuring rode, used in the same way

Qualitative = implies capacities have appeared or disappeared, implies there is no common measuring rod. Prevalent in childhood and other life transitions

Measuring change over time

Studies tend to summarise individual differences to mean patterns, we asses change / stability based on:

Mean level – do average trait scores increase or decrease

Rank order – do relative standings change or stay the same

Change in intelligence

-       Relatively stable over the lifespan, but declines in older age

-       Studies affected by drop out and decline

-       These mean level smoothed population level patterns miss a lot of individual differences

Change in personality

-       Personality is relatively stable development over the lifespan

-       The ‘maturation principle’ – we tend to become more conscious, emotionally stable, and agreeable over the lifespan

Genetics and heritability

All psychological characteristics are heritable

-       Intelligence

-       Personality

-       Psychopathology

-       Motivations / goals

-       Interests

-       Happiness

-       Even junk behaviours like chewing gum

Key terms

G = genes

E = environment

P = phenotype

h = heritability

e = environmental effects

r = gene-environment correlations

Twin studies

Natural experiment: monozygotic and dizygotic twins

-       Raised together and separately, could teaser apart from the strength of genes that effect of shared vs non shared environment

-       - compare the strength of the correlations between traits in mz and dz

-       Varies the amount of genetic material that they share

-       Can examine the amount of environmental influence

What is heritability

The proportion (the ratio / fraction) of population variance that can be attributed to genetic influences (genetic variance) calculated by genetic variance over observed variance

-       Heritability is specific to populations and environmental circumstances

-       Experiment:

-       Plant genetically identical corn seeds in different fields = different plant outcomes are all due to variation in conditions

-       Plant genetically diverse seeds in the same field = different plant outcomes all die to genetic variation

What about the rest

-       The rest of the variance is shared or non-shared environmental factors

Shared environmental factors = refers to environmental factors that actually act to make family members more similar e.g. parenting styles

Non shared environmental factors = refers top environmental factors that act to make family members different e.g. educational experiences

Laws by behavioural genetics

Developed by Turkheimer

1.     All human behavioural traits are heritable

2.     Shared environmental influences tend to be weaker than genetic influence

3.     Neither accounts for all variance

4.     A typical human trait is associated with very many genes, each of which accounts for miniscule amounts of variance

-       We cant assume that correlations between life circumstances and alter outcomes are casual

-       Environmental influences are idiosyncratic

o   They transact with genes in individual ways

o   There are very few direct main effects out there – we have not identified many specific effects of non-shared environmental influences

How can we find genes

-       Genome technology = scans peoples genotypes (their genetic profiles) and examine the relations with their phenotypes

-       Can now identify specific genetic components (alleles, variants for genes)

Influences of environment

Faith in nature and the role of environment is an extremely strong implicit belief in psychology

Standard social science model

-       Develop ideas about certain environment causes (e.g. social priming) and some ‘outcome’ (e.g. specific behaviour)

-       Test for associations between causes and outcomes

-       Problem; other variables are connected too

In twin studies we describe and distinguish genetic environmental influences using the ACE model

A = (addictive) genetic variance

C = common environmental variance (parenting)

E = (non-shared) environmental variance

-       Parents are important but they do not make a difference; peers are far more developmentally significant than parents

Non-shared environments

-       These influences are often studied through life events (time discrete transition that mar the beginning or end of a specific status)

-       These are stable, come with clear punishment and reward structures and generalise across many traits i.e. they influence broadly

-       Many life events are universal, but we do not experience identical ones thus they are non-shared (universal effects don’t create a difference)

-       Problems; are life events independent of traits? Everyone equally likely to get a divorce, have children, be fired, go back to school etc

Educational exposure – IQ

Education reforms bringing longer schooling results in a higher average IQ

-       But they influence a cohort alike, so does not explain individual differences

-       Going to school earlier because of birth date mean higher IQ at lower ages but fades off since later starters catch up with schooling years

-       Being at school longer is associated with higher IQ

-        But staying at school fort longer is not random but related to pre-existing IQ

Taking an active role in development

Our genes predispose us to select ourselves into certain experiences that enables us to develop our traits

-       Intelligent people enter higher education

-       Extroverted people go to parties

Our genes and the environment we choose are intertwined and both are heritable

-       These interactions are called gene-environment correlations

Peroanlity dynamics

We can think of change at different time scales;

-       Short term (traits influence how we respond to momentary situational cues)

-       Long term (environments constrain of facilities the development of our traits)

How is the five factor theory represented

Personality is made up of two core attributes

-       Basic tendencies (biological, innate, genetic)

-       Characteristic adaptions (learned beliefs, attributes and behaviours derived from basic tendencies and our environment)