Differential psychology

• What is differential psychology?


  Study of individual differences.
• What is the difference between an experimental psychologist and a correlation psychologist?

  Experimental psychologist, manipulate conditions to see what happens, e.g. social and cognitive.

  Correlation psychologists, identify and measure freestanding patterns of nature that we cannot directly control e.g. differential
• What is the index difference of correlation and experimental methodologies in psychology?

  Correlations: study of genetic and developmental sources of individual differences in personality and intelligence and the implications naturalistic, but can feel technology situations also constrain behaviour.

  Experimental: manipulate situations circumstances in observe how they’re manipulations of a typical behaviour and performance, but can feel to acknowledged that some error in the model is systematic, i.e. due to individual differences.
• What are the physical attributes we can measure?

  Basic: height weight body build skin hair.

  Physiological/medical: blood pressure, hormonal levels, metabolic rates, fitness levels, glucose and lactose tolerance, fertility.

  Surprising: location of organs, number and shape of bones, fingers.

  Developmental: readiness for learning, reading, pubertal timing, ageing
• What are more in-depth differences psychologist are interested in isn‘t “bodily”?

  Demographic status: age, sex, marital status, religious affiliation, political views. age, sex, marital status, religious, affiliation, political views.

  Lifestyle factors: diet, exercise, alcohol consumption values.

  Experiences and upbringing: family wealth, educational opportunities, experience of involuntary, traumatic events, victimhood of crime.

  Psychological attributes: motivations, goals, attitudes, risk tolerance, gender identity, sexuality.
• What is variance and why does it occur?

  Differences develop over time creating variation. This is measured in psychology as variance, i.e. expected, squared deviation of a random variable from its mean. This can be more easily interpreted as the standard deviation.
• What individual differences are psychologists interested in when it comes to variation?

  What does the word personality mean to you?

  What do you find interesting when you think about personality?

  What does the word intelligence mean to you?

  What do you find interesting when you think about intelligence?
• What is intelligence?


  A very general mental capacity that among other things involves the ability to reason plan solve problems think of strictly comprehend complex ideas, learn quickly and learn from experience. It reflects a broader and deeper capability for comprehending our surroundings.
• What is personality?

  An individual characteristics, style behaving, thinking, and feeling together with the psychological mechanisms hidden or not behind them brackets (Funder, 2016).

  It isn’t a single unitary treat. It has lots of different traits organised hierarchically.
• Why is it important to study variation and differences?

  Differences in personality and intelligence predict life outcomes, e.g. more intelligent people are more likely to do well in school. These relationships or not predetermined or traits are not her feet and other factors affect.
• What are the difficulties in measuring individual differences?


  You can’t directly observe many of the characteristics we are interested in multi stage process for measurement:

  • Define the trait
  • Operationalise it by rating psychometric items to create a measuring tool
  • Test of reliability and validity of the measurement tool.
  • Examine the shared variance amongst items
  • Some left over as measurement error. Is there anything else interesting here?
• What is the history of differential. (pre-psychology?)

  Several accounts of individual differences provided before formalisation of psychology as a field of scientific study.
• What is the history of differential - early personality researchers.

  Early personality psychologists develop the lexical hypothesis, and the idea that personality is included in language through traits (Allport, Lewin, Murray, Thurstone, Fiske, Norman, Digman, Goldberg)
• what did Francis Galton and Karl Pearson research early intelligence?

  Psychological attributes can be measured and analysed

  Psychological characteristics are inherited

  Many statistics we use today: correlations, P–values, chi-square test
• Who and what were eugenicists?


  Influential pioneers, differential psychology, e.g. Galton and Pearson, believed in using statistics to demonstrate that some races were superior to others e.g. through higher IQ scores.
• Who was Freud?

  Psychodynamic psychologist whose ideas may sound silly to us today, e.g. Oedipus complex, but Freud described many concept so so used in psychology, e.g. projection and unconsciousness.
• What are constructs and how do we operationalise them?

  Reserve patterns of behaviour or performance and make assumptions about hidden psychological characteristics that could be causing them.
• What does measurement in psychology require?

  Ground truth or real fixed quantity, e.g. hate that we can derive measurement units from.
• What does it mean to measure something well?

  Are measurement should be consistent over time (in line with theory).

  • After a certain point height measurement should be consistent.
  • How does not change with context.
• Who should make observations about individual differences?

  Individuals are the only ones who have direct access to internal psychological characteristics. However, other individuals may be better judges of her. We appear in her internal experience as compare to others.
• Where does errors in psychological measurement come from?

  Impacts of stochastic (random) and systematic processes that deviate scores away from the true patterns (e.g. social desirability bias).

  interpretive disagreements about the scale among creators and users (e.g. cultural/age, differences, in questionnaire language)
• How can bias come into play and testing?

  Bias is anything that systematically distorts her accurately, a test catches its target construct (e.g. your ruler is not long enough to fully measure height)
• What is the difference between errors in bias and noise?

  Bias refers to mistakes and something objective (i.e. systematic distortion away from our true value).

  Noise refers to aggregation of errors (both stochastic and systematic) that produce temporary deviations from overall patterns.

  If we examine the impact of noise, we can learn more about the process as underlie them (inductive). If we understand the sources of bias, we should be able to minimalise them (deductive).
• What is the classical test theory?

  The foundation of psychometrics (alternative approaches available today). Central tenet is:

  observed score = true score + error.

  Eric and include systematic + non-systematic influences.
• What are the components of a test score?

  Simple formula – the better are measurement the less error. There is in the calculation of observed score (i.e. the closer is to the “truth”)
• What is psychometrics?

  The measurement of psychological characteristics.
• What are the two main criteria by which we judge psychometrics?

  Reliability and validity
• How do we judge psychometrics through reliability?

  Different forms of the same test (internal consistency, parallel forms)

  Completing the test at different times (i.e. test retest, reliability)

  Different Reiters (i.e. cross rater agreement)
• How do we judge psychometrics through validity?

  Content and construct validity (how well does the test capture its target construct?)

  Face validity (does the test makes sense and look right)

  Convergent and discriminant validity (does attest correlate with other test appropriately

  Criterion and predictive validity. (Does the test predict relevant outcomes)
• What is the difference between reliability and validity?

  Reliability refers to the consistency or stability of a measurement, while validity refers to the accuracy or truthfulness of a measurement.
• What is the difference between correlation and factor analysis?

  Correlation: measure of association between two variables.

  Factor analysis: measure of association between many variables.
• What is the five big personality traits?

  Openness, Conscientiousness, Extraversion, Agreeableness, Neuroticism.
• what did Alport and Odburt do? (1936)

  The lexical hypothesis dynasty: 4504 English adjectives describing people. Self-reported of clusters.

  Cattle whittle down to 171 factor analysis to 16.

  Tubes and Christal argued only 5/171 was important.

  1980 – Goldberg, Digman et al. argued this is the best.

  Costa and Mcrae (1985) create the five factor NEO, creating FF Theory to support
• Who created the five factor model?

  Costa and McCrae
• What was missing from the five factor model?

  Antisocial behaviour (Alienation, aggression, manipulation, cruelty, and greed.)

  Social dominance, competitiveness and ambition (risk-taking, thrill-seeking, assertiveness)

  Morality, spirituality, religiosity.

  Psychopathology.
• How many unique facets does the five factor model have compared to new models?

  30. New models have 70+ (Irwing et al. 2023)
• Why is the five factor model heavily criticised?

  Derived without an underlying theory of personality.

  Derived using subjective methods

  Saturated with social desirability

  Has “cloudy” broad trait definitions that mask, a lack of consensus and vary across models.
• What does the FFM predict?

  High N, Low A = psychopathology

  High C & O, Low N = predicts, educational achievement, and attainment and work performance.

  Low A predicts higher income

  High C predicts health.
• Despite limitations, why does the five factor model work?


  Personality influences are behaviours in life choices.

  Despite cloudy definition of broad factors, they are psychologically relevant.

  Saturated with social desirability, socially desirable behaviour is socially rewarded?

  Content overlap between items (e.g. conscientiousness, predicts, obesity, because it contains items related to impulsive eating)
• What is the five factor theory?

  These factors reflect biological contributions that are relatively fixed and stable after 30, the biological seeds of which are present from birth.