Personality 1 Trait Theories and Measurement Jose L

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Personality 1: Trait Theories and Measurement Josée L. Jarry, Ph. D. , C. Psych.

Personality 1: Trait Theories and Measurement Josée L. Jarry, Ph. D. , C. Psych. Introduction to Psychology Department of Psychology University of Toronto July 21, 2003

Personality: Definition • Refers to the person's general style of interaction with the world

Personality: Definition • Refers to the person's general style of interaction with the world • People differ from one another in their style of behaviour, in ways that are at least relatively consistent across time and situations • The study of personality focuses on differences between people.

Traits • The most central concept in personality psychology • Relatively stable predisposition to

Traits • The most central concept in personality psychology • Relatively stable predisposition to behave in a certain way • Part of the person, not part of the environment • The actual manifestation of traits in the form of behaviour usually requires some perceived cue or trigger in the environment.

Traits and States • States of motivation and emotions are, like traits, defined as

Traits and States • States of motivation and emotions are, like traits, defined as inner entities that can be inferred from observed behaviour • However traits are enduring, states are temporary • A trait might be defined as an enduring attribute that describes one's likelihood of entering temporarily into a particular state.

Trait Theories • The goal of trait theories is to specify a manageable set

Trait Theories • The goal of trait theories is to specify a manageable set of distinct personality dimensions that can be used to summarize the fundamental psychological differences among individuals • Traits are not explanations of individual differences • Traits are inferred from behaviour.

Hierarchical Organization of Traits • Behaviours and traits are linked to one another in

Hierarchical Organization of Traits • Behaviours and traits are linked to one another in a hierarchical fashion • Specific behaviours are at the bottom of the hierarchy • Surface traits are linked directly to a set of related behaviours • Central traits link related surface traits to one another • Central traits are the fundamental dimensions of personality.

Elements of Trait Theories • The set of central traits that is deemed most

Elements of Trait Theories • The set of central traits that is deemed most useful for describing the psychological differences among individuals • The surface traits that are linked to each central traits • Objective means of measuring the surface and central traits – Usually involves a questionnaire, in which the person describes his or her own behaviour.

Building a Trait Theory (1) • Bottom up process – collect a large amount

Building a Trait Theory (1) • Bottom up process – collect a large amount of data about the specific behaviours of a large number of people – statistical means to determine which classes of behaviours correlate most strongly with one another, indicating surface traits – and which surface traits correlate most strongly with one another, indicating central traits – generate a hierarchical set of proposed traits and give them names.

Building a Trait Theory (2) – develop a questionnaire that can be used reliably

Building a Trait Theory (2) – develop a questionnaire that can be used reliably to measure the degree to which any given person manifests each of the traits specified by theory – the primary goal of any trait theory is to account for the greatest amount of variation among individuals, while minimizing the number of separate central-trait dimensions used – In the ideal theory, the central traits are nonredundant.

Cattell's 16 PF (1) • Raymond Cattell (1950) – began his research by condensing

Cattell's 16 PF (1) • Raymond Cattell (1950) – began his research by condensing 18, 000 English adjectives describing personality, down to about 170 that are logically different from one another – these were his initial set of surface traits – large numbers of people rated themselves on each of the surface traits – used factor analysis to determine which surface traits correlated most with one another.

Cattell's 16 PF (2) – identified a preliminary set of central traits by finding

Cattell's 16 PF (2) – identified a preliminary set of central traits by finding clusters of surface traits that correlated strongly with one another within the clusters but not across the clusters – developed various questionnaires aimed at assessing these traits – used the questionnaire results to modify the set of central traits – identified 16 central traits – developed a questionnaire called the “ 16 PF Questionnaire” to measure them.

The Eysenck Personality Inventory • Hans Eysenck (1952) • Introversion-extroversion – is related to

The Eysenck Personality Inventory • Hans Eysenck (1952) • Introversion-extroversion – is related to the person's tendency to avoid or seek excitement in the external environment • Neuroticism-stability – pertains to one's tendency to become emotionally upset • Psychoticism-nonpsychoticism – pertains to a lack of concern for others vs. peaceableness and empathy.

The Big-Five Theory • Cattell's 16 factor theory is overly complex, with redundant factors

The Big-Five Theory • Cattell's 16 factor theory is overly complex, with redundant factors • Eysenck's three-dimensional theory is oversimplified • Researchers conducting factor analytic studies in various country, in several languages, find consistent results • The most efficient set of central traits for describing personality consists of 5 traits.

Predictive Value of Traits • Are personality traits consistent across situations or are they

Predictive Value of Traits • Are personality traits consistent across situations or are they specific to particular situations? • Are personality traits stable through time?

The Stability of Personality Measures Over Time • Studies in which people rate themselves

The Stability of Personality Measures Over Time • Studies in which people rate themselves or are rated by others on personality questionnaires • At widely separated times in their lives • The results indicate high stability of personality throughout adulthood • Correlation coefficients on repeated measures of the Big Five typically range from. 50 to. 70 • Even with time spans between the first and second test of 30 or 40 years.

Consistency Across Situations (1) • Walter Mischel (1968, 1984) – describing personality in situations

Consistency Across Situations (1) • Walter Mischel (1968, 1984) – describing personality in situations specific terms is more useful in predicting behaviour than are global traits statements • Social learning approach – personality characteristics are learned habits of thinking and behaving, which are acquired and manifested in particular social situations.

Consistency Across Situations (2) • Hugh Hartshorne and Mark May (1928) – conducted a

Consistency Across Situations (2) • Hugh Hartshorne and Mark May (1928) – conducted a classic study of morality involving thousands of schoolchildren – children were provided with opportunities to be dishonest in a wide variety of situations – the results showed high correlations within any given type of situation, – but low correlations across different situations.

Consistency Across Situations (3) • Mischel and Peake (1982) – assessed repeatedly by direct

Consistency Across Situations (3) • Mischel and Peake (1982) – assessed repeatedly by direct observation 19 different forms of behaviour presumed to be related to the trait of conscientiousness – they found high consistency within any one of these measures, – but relatively low consistency across measures.

Reanalysis of the Mischel & Peake Study • Factor analysis showed that the measures

Reanalysis of the Mischel & Peake Study • Factor analysis showed that the measures clustered in separate traits • Within these traits, there was high correlation across situations, • but not necessarily between the traits • The lack of correlations between behaviours supposed to measure conscientiousness meant that these behaviours clustered in different traits rather than in one global trait.

Reanalysis of the Hartshorne & May Study • Little consistency was found when the

Reanalysis of the Hartshorne & May Study • Little consistency was found when the behaviours related to dishonesty were measured within one individual, between situations • When comparisons were made between children, averaging situations within individuals, • Large differences existed between individuals, larger than would be accounted for by chance.

Biological Foundations of Traits • Eysenck – proposed that individual differences in extroversion-introversion stem

Biological Foundations of Traits • Eysenck – proposed that individual differences in extroversion-introversion stem from differences in how easily the higher parts of the brain are aroused by sensory input – all people seek an optimal level of brain arousal – but to achieve that level, extroverts require more stimulation than do introverts – introverts avoid stimulating environments to prevent their arousal level from exceeding the optimum.

The Heritability of Traits • Twin studies – standard personality questionnaires are administered to

The Heritability of Traits • Twin studies – standard personality questionnaires are administered to identical and fraternal twins – identical twins are much more similar than are fraternal twins raised together on every personality dimension measured – same results are found for twins raised apart – even trait that logically should be influenced by learning are found to be heritable.

Reliability (1) • Refers to the stability of the scores • Does the test

Reliability (1) • Refers to the stability of the scores • Does the test measure consistently what it is supposed to measure? • The capacity of the test to yield the same or comparable scores on different testing occasions on a given population • Measured with the Reliability Coefficient.

Reliability (1) • Test-retest reliability – assesses the stability of the scores over time

Reliability (1) • Test-retest reliability – assesses the stability of the scores over time – administer the same test to the same population twice • Parallel-form reliability – administer similar forms of the test to the same population twice • Split-half reliability – measure of internal consistency – administer the test once – split the items in two and perform a correlation.

Validity (1) • Refers to the meaning of the scores • Does the test

Validity (1) • Refers to the meaning of the scores • Does the test measure what it is supposed to measure? • Measured with a validity coefficient.

Validity (2) • Predictive or criterion validity – consists of comparing the performance of

Validity (2) • Predictive or criterion validity – consists of comparing the performance of the test with a real world measure of the trait • Construct validity – related to theory underlying the test – does the test measure theoretical construct it is supposed to measure? – can be done by deriving a network of predictions from theory – can be done by correlating the new test’s scores with scores on existing measures.