Personality Psychology: PERSONALITY ASSESSMENT

MBB2

Domains of personality assessment

• Organisational psychology

• Clinical psychology

• Educational psychology

• Counselling psychology

• Forensic psychology

• Assessment, and personality assessment in particular, is a core element of psychological practice

Measuring the unmeasurable?

• Personality assessment faces serious challenges

• Assessment appears to be subjective

• There is no infallible source of information about the person

• The ‘object’ knows it is being measured

• Personality traits are not directly observable

Measurement quality & confidence

• The degree to which personality is measured well is captured by two main concepts

• Reliability: does the measurement yield consistent, dependable & error-free information

• Validity: does the measurement assess what it is intended to assess & is it useful

Reliability: three varieties

• Internal consistency

• Inter-rater reliability

• Re-test reliability

• Three kinds of measurement error: within the test, between testers, and over time

• High reliability = high consistency = low error

Internal consistency

• Do the components of the test all cohere?

• All test items should correlate with one another

Inter-rater reliability

• Does the test provide the same information about the person when different people administer it?

Re-test reliability

• Does the test yield similar scores when it is administered to the same person on different occasions?

Validity

• Validity has two components

• Does the test measure what it is intended to measure?

  • Content validity

  • Convergent validity

  • Discriminant validity

• Does the test provide practically useful information

  • Predictive validity

Reliability & validity

• So for a good test of trait X …

  • All items should intercorrelate

  • The same score should occur whoever gives it

  • People should get similar scores when they do it twice

  • All items should clearly relate to the meaning of X

  • It should correlate strongly with other measures of X

  • It should not correlate with measures of Y & Z

  • It should correlate with things that X is related to

• Reliability & validity are both essential, but if reliability is low, validity cannot be high: a test full of measurement error can’t predict anything

Reliability & validity

• Unreliability exists when there is inconsistency in what the test measures (scatter)

• Invalidity exists when the test does not measure what it should (targeting the bullseye

Kinds of personality measurement

• Many different modes of personality assessment

• Interviews

• Personality inventories

• Projective tests

• Implicit personality

Interviews

• Interviews are rarely used in personality assessment

  • Time-consuming & labour-intensive

  • Subjective (i.e., poor inter-rater reliability)

  • Interview interactions are prone to biases

    • Halo effect, self-fulfilling prophecy, confirmation bias

• Sometimes they are used for assessing attributes where the person may not be a reliable informant, and/or where interpersonal & nonverbal behaviour may be revealing

  • Personality disorder

Interviews

• Forms

• Structured

• Unstructured

• Semi-structured

  • Combines structure & flexibility

• ‘Provocative’

  • Type A personality

Inventories

• Self-report personality tests

• Composed of multiple items Items form scales

  • Omnibus tests with many scales

  • Single-scale tests

  • Generally, at least 10 items per scale

• Variety of response scales

  • True/false

  • Likert scales (strongly disagree strongly agree)

Inventory development

• Item generation

• Pilot testing

• Item analysis

  • Check internal consistency

  • Factor analysis

• Select optimal items for final scales

• Re-test on new sample

• Correlate with other tests and prediction criteria

• Develop norms to allow score comparison

Problems of self-report

• Inventories are vulnerable to response biases & limitations of self-knowledge

• Longer tests include validity scales to check for this

  • Lie scales (faking good)

  • Infrequency scales (faking bad, random responding)

  • Defensiveness scales (subtle guardedness)

  • Inconsistency scales (carelessness, random responding)

Example: the MMPI

• Developed in 1940s for comprehensive clinical personality assessment

• 10 clinical scales, 3 validity scales; 566 items

• Scale development by selecting items that best differentiated known groups

• Scale scores converted to T-scores (M=50, SD=10)

• Interpretation of scale profiles

MMPI profile

• Check validity scales High F scale

• Identify peaks (T>65) PD & SC scales

• Inspect ‘atlas’ for profile code 48 code

MMPI 4/8 code

• odd, peculiar

• non-conforming and resentful of authority

• problems with impulse control

• excessive drinking and drug abuse

• Deep feelings of insecurity;

• avoids close relationships, impaired empathy;

• withdraws into fantasy or strikes out in anger as defence against being hurt

• most common diagnoses are schizophrenia (paranoid type), schizoid personality & paranoid personality

Projective tests

• Developed to bypass problems of self-report

• Aim to penetrate to deeper levels of personality

  • Dynamics, object relations, core motives

• Allied with the psychoanalytic approach

• Involve deliberate ambiguity & open-endedness

  • Ambiguous stimuli

  • Unstructured responses

• Based on the assumption that personality will be ‘projected’ onto stimuli without defensive

Thematic Apperception Test

• Developed by Henry Murray

• Idiographic approach

• Series of monochromatic images

• Person tells extended story about what is happening in the picture

• Responses coded for repeated themes in the stories: motives attributed to protagonists, interpersonal conflict, ways of handling conflict etc

• Few widely accepted scoring conventions – a recipe for inter-scorer unreliability – but …

• Rigorous scoring systems for defence mechanisms

  • Denial & projection (Cramer)

• System for scoring motives

  • Need for achievement (McClelland); does not correlate with self-reported achievement striving

Rorschach Test

• Evolved from 19th Century parlour game

• Series of symmetrical inkblots

• Person says what object(s) the person sees (the “percept”) and what aspects of the blot lead them to see it

• Responses are scored on numerous dimensions

• Number of distinct precepts

• Complexity/integration of precepts

• Content themes

• Plausibility of precepts (i.e., are they recognizable)

• Response to colour

• Use of shading, blank space

Critiques of projective tests

• Time consuming

• Encourages ‘wild’, unconstrained interpretation

• Low inter-scorer reliability

• Predictive validity is generally weak compared to self-report tests

• Often there is little ‘incremental validity’ beyond self-report tests

Implicit tests

• New form of testing based on rapid, ‘automatic’ responses

• In principle difficult to fake & less susceptible to response bias

• Early evidence suggests these methods have promise

Example: Implicit Association Test (IAT)

• Four sets of words

  • Self: me, my, mine

  • Not-self: they, them, their

  • Extraversion: active, confident, outgoing

  • Introversion: aloof, reserved, serious

• Two ‘blocks’ of trials where person must rapidly classify words into different pairings of words

• If ‘self’ is more associated with ‘introversion’, classification will be quicker for the LEFT block

• Quicker classification for the RIGHT block if ‘self’ is associated with ‘extraversion’