Differential Psychology

Transcription

1 Differential Psychology Part 1: History of the influences in the development of intelligence theory & testing Dr Andreas Fichtinger

2 History of Intelligence Testing Intelligence: What is it?

3 Overview Early theorists in intelligence: Galton; Binet; Terman & Yerkes General intelligence and its measurement: Spearman g, the Wechsler & Raven s Matrices Intelligence tests Multifactor theorists: Thurstone; Cattell; Guilford Hierarchal theorists: Vernon; Carroll Multiple intelligences & triarchic model of intelligence Gardner; Sternberg

4 History of intelligence testing History of intelligence is largely a history of intelligence testing If something exists, it exists in some amount. If it exists in some amount, then it is capable of being measured. (French philosopher Rene Descartes, ) Modern definition of intelligence testing: an attempt to quantify and measure individual differences underlying performance in an objective, scientific manner (Chamorro-Premuzic, 2008). Accordingly differential psychologists were dedicated on designing psychometric instruments to compare individuals on intelligence.

5 Early theorists in intelligence First modern attempt (late 19 th century) Sir Francis Galton, UK Origins of IQ testing (early 20 th century) Alfred Binet, France First appearance of IQ (1916) Lewis Terman, US Wilhelm Stern, Germany Group intelligence testing (1920 s) Robert Yerkes, US

6 Early theorists in intelligence Francis Galton - first modern attempt in late 1800 s Intelligence tests grounded in work of Galton First scientific attempt to conceptualise individual differences in cognitive ability Considered the father of the study of individual differences Hereditary genius: idea that different levels of intelligence are determined by hereditary or genetic factors

7 Early theorists in intelligence Measurement of intelligence seen as direct measure of underlying intelligence Galton suggested reaction time as feasible approach pursued various sensori-motor measurements More recent approaches support Galton-like approaches by assessing integrity of central nervous system (Weinberg, 1989) inherent capabilities (Intelligence A) as opposed to manifestations of intelligence in everyday life (Intelligence B)

8 Early theorists in intelligence Alfred Binet origins of IQ testing (early 1900 s, France) Father of IQ testing In 1904 commissioned by French Ministry of Public Instruction to develop techniques identifying primary grade children who lack success in normal classrooms to provide them with special education In 1905 Binet & Theodore Simon developed the first IQ test, the Binet-Simon scale Various revisions: the 3 rd edition in 1911 was model for many future tests

9 Early theorists in intelligence Binet took a pragmatic approach choosing a series of 30 short tasks related to everyday problems of life such as Name parts of the body Compare lengths & weights Counting coins Assessing which of several faces are prettier Naming objects in a picture Word definition Filling in the missing words in sentences

10 Early theorists in intelligence All tasks involved basic processes of reasoning Tasks were arranged so as to be of increasing difficulty each level of tests matched a specific developmental level all tests at a given level were capable of being solved by any normal child in that specific age-group Binet-Simon scale was turning point in psychology new type of test in which average level of performance was criterion. Test results proved to be correlated with other criteria (e.g. results of examinations, assessments of teacher, )

11 Early theorists in intelligence Lewis Terman ( ) professor at Stanford University, US Identified problems with Binet-Simon scale in population of American school children Revised test in 1916 Stanford-Binet test adapted some items & added others established new age norms (e.g yrs) extended upper age limit to superior adults Terman introduced further modification = calculation of scores for the first time scores expressed as Intelligence Quotient (IQ) a term introduced by German Wilhelm Stern in 1912 Stanford-Binet scale had good reliability for adults, but not for children (e.g. Weinberg, 1989)

12 Early theorists in intelligence IQ scores quantified intellectual functioning to allow comparisons among individuals Formula: IQ = MA/ CA x 100 Mental age (MA) divided by Chronological age (CA), multiplied by 100 Stern s ratio of Chronological age to Mental age, used to develop concept of intelligence quotient (IQ) MA CA MA/CA IQ

13 Early theorists in intelligence Robert Yerkes Army tests (WWI) At beginning of WWI Army was faced assessing intelligence of great numbers of recruits in order to screen to classify to assign them to suitable tasks. Stanford-Binet test not suitable because required highly trained person for individual administration too time consuming too costly for large scale use Yerkes - a psychologist & army major was commissioned by US Army to develop group intelligence testing

14 Early theorists in intelligence Yerkes & a group of 40 Psychologists developed first Group Intelligence Tests Army Alpha Test Army Beta Test version for non-english speaking & illiterate people (instruction by demonstration or pantomime) More than 1 million people were tested but not until war Work enhanced status of psychology Value of group testing seen by industry, business & education Note, validity of Beta test is questionable (e.g. Gould, 1981)

15 Yerkes group intelligence tests The Alpha Test Oral directions Arithmetical problems Practical judgement Synonyms antonyms Disarranged sentences Uncompleted series of numbers Analogies Information The Beta Test Maze task Cube analysis X-O series Digit symbols Number symbols Picture Geometrical construction

16 Early theorists in intelligence - summary So far approaches to intelligence were very pragmatic (i.e. tests developed for particular needs) Another approach to understanding intelligence involved analysing data that was already collected Method of factor analysis introduced to intelligence measurement

17 General intelligence & its measurement Charles Spearman: g (1920 s) Spearman analysed relations among experimental intelligence tests using factor analysis He observed correlations among performance on variety of intellectual tasks He argued that people who do well on some intelligence tests also do well on a variety of intellectual tasks and vice versa.

18 General intelligence & its measurement Thus he proposed 2-factor theory of intelligence: General ability g : required for performance of mental tasks of all kinds called mental energy underlying specific factors Special ability: required for performance on just one kind of mental test E.g. Scores on a verbal comprehension test are largely determined by one s level of general intelligence but also affected by one s specific ability to perform verbal comprehension tasks.

19 General intelligence & its measurement Main thrust of Spearman s work was idea of a general intellectual capacity formed major theoretical platform for many subsequent approaches to intelligence Spearman was enthusiastic about general ability g also reflected in promotion of controversial political arguments such as voting rights should be restricted to people whose g exceeded a certain level Only people with certain g should be allowed to have offspring (eugenistic view) Factor g remains controversial!

20 General intelligence & its measurement David Wechsler: Intelligence Scales for Adults & Children (1939-present) Wechsler identified problems with Standord-Binet scales too verbally loaded for use with adults Designed instrument with sub-tests to measure both (i) verbal & (ii) nonverbal abilities informed by many other tests (e.g. Army Alpha Test) Adopted mean score of 100, since Stanford-Binet metric had become universally accepted Original Wechsler Bellevue test (1939) quite successful in civilian & military applications.

21 General intelligence & its measurement In 1949, the Wechsler Intelligence Scale for Children (WISC) was introduced In 1955, a revised version of the adult scales was produced, the Wechsler Adult Intelligence Scale (WAIS). All Wechsler scales possess good psychometric properties (validity & reliability) Since widely used, here are some illustrative examples:

22 The Wechsler Tests Arithmetic (verbal) Block design (performance) Comprehension (verbal) Digit span (verbal) Digit symbol (performance) Information (verbal) Object assembly (performance) Picture arrangement (performance) Picture completion (performance) Similarities (verbal) Vocabulary (verbal).

23 Examples from the Wechsler Adult Intelligence Scale (Continued) Figure Simulated items similar to those in the Wechsler Adult Intelligence Scale: matrix reasoning (d), picture completion (e) Source: Simulated items similar to those from Wechsler Adult Intelligence Scale, Third Edition. Copyright 2005 by Harcourt Assessment, Inc. Reproduced with permission. All rights reserved

24 Examples from the Wechsler Adult Intelligence Scale (Continued) Simulated items similar to those in the Wechsler Adult Intelligence Scale: object assembly and Wechslerlike questions (f) (Continued) Figure Source: Simulated items similar to those from Wechsler Adult Intelligence Scale, Third Edition. Copyright 2005 by Harcourt Assessment, Inc. Reproduced with permission. All rights reserved

25 Multifactor theorists Louis Thurstone: Primary Mental Abilities (1930 s) Thurstone questioned Spearman s general intelligence factor g He devised a competing statistical technique called multiple factor analysis He argued that g is in fact a second order factor, which arises only because the first order factors are related to one another Thus, Thurstone identified 7 primary mental abilities he judged more important than g

26 Multifactor theorists Thurstone s 7 primary mental abilities: 1. Verbal comprehension 2. Word fluency 3. Number 4. Space (spatial visualizations) 5. Associative memory 6. Perceptual speed 7. Reasoning

27 Multifactor theorists Thurstone s approach first multifactor approach to intelligence Important argument & findings intelligence is better described by distinct primary mental abilities (rather than a single factor g ) But rarely used was not able to more accurately predict academic or occupational performance than general intelligence

28 Multifactor theorists Raymond Cattell fluid & crystallised intelligence (1960 s) Suggested 2 related but distinct components of intelligence Fluid intelligence primary reasoning ability ability to see relationships, as in analogies and letter & number series decreases with age Crystallised intelligence factual knowledge acquired knowledge & skills increases with age

29 Multifactor theorists Some examples: Mathematicians and scientists require fluid intelligence & often produce their best work in their 20s & 30s. Historians and philosophers produce their best work in their 40 s & 50 s as they have accumulated more knowledge (crystallised intelligence)

30 Cattell s three components of intelligence gf gsar Non-verbal tests e.g., numerical Performance tests e.g. Short-term memory gc latent correlation measured through Verbal & knowledge tests, e.g. vocabulary Source: Chamorro-Premuzic, T. (2008) Personality and individual differences. BPS Blackwell

31 Multifactor theorists Guilford: many factors (1960-present) refused to acknowledge existence of any general factor of intelligence proposed that intelligence comprises of 180 elementary abilities The 180 elementary abilities are made up of a combination of 3 dimensions: Operations: what a person does (6 types) Contents: material on which operations are performed (5-types) Products: form in which information is stored & processed (6-types) Each combination of a specific operation, type of content and specific type of product defines a unique type of intelligence (6x5x6=180) No significant influence on intelligence testing not practical!

32 Guilford s Structure of Intellect (SI) theory Figure Guilford s Structure of Intellect (SI) theory Source: From Guilford, J.P. (1967). Nature of human intelligence. New York: McGraw-Hill Companies, Inc. Copyright The McGraw- Hill Companies, Inc. Reprinted with permission

33 Hierarchical theorists Vernon & Caroll: Hierarchical Approaches (1960 s-present) Hierarchical Approaches most widely accepted factorial description of intelligence Spearman s single g factor & Thurstone s multiple primary mental abilities are accepted Hierarchical descriptions of intelligence fill in gaps between extreme approaches of Spearman & Thurstone

34 Hierarchical theorists Vernon s suggested a hierarchical theory of intelligence (1960, 1965, 1971) Intelligence described as comprising abilities at varying levels of generality: Highest level of generality: g as defined by Spearman Next level are major group factors, such as Verbal-educational ability Practical-mechanical ability Next level are minor group factors Lowest level are specific factors: (similar to Spearman)

35 Vernon s hierarchical theory of intelligence Source: Maltby, Day & Macaskill (2010). Individual Differences and Intelligence (2 nd ed.). Pearson Education Ltd.

36 Three-stratum Model of Human Cognitive Abilities (Caroll, 1993) Stratum I Specific intelligences Stratum II Fluid intelligence abbreviated to Gf Crystallised intelligence abbreviated to Gc General memory and learning abbreviated to Gy Broad visual perception abbreviated to Gv Broad auditory perception abbreviated to Gu Broad retrieval ability abbreviated to Gr Broad cognitive speediness abbreviated to Gs Processing speed abbreviated to Gt Stratum III g.

37 Multiple intelligences & triarchic model of intelligence Howard Gardner: Multiple intelligences (1980s present) Supported Thurstone s multi-factor approach Gardner identified 7 different types of intelligence These different intelligences are independent of one another Critics argue that not all are intelligence (rather talent or interest)

38 Gardner s multiple intelligences 1. Linguistic 2. Logical-mathematical 3. Spatial 4. Musical 5. Bodily kinaesthetic 6. Interpersonal (social skills) 7. Intrapersonal (self-understanding) 8. Naturalist 9. Existentialist

39 Multiple intelligences & triarchic model of intelligence Robert Sternberg (1970s present) Suggested a thriarchic theory of intelligence which includes: Analytical/ academic intelligence Creative intelligence Practical intelligence These various intelligences are independent from each other Most evidence provided for practical intelligence (Sternberg & Wagner, 1993) facilitated through design of test

40 Sternberg s triarchic theory of intelligence The componential sub-theory (analytical intelligence) Metacomponents Performance components Knowledge-acquisition components The contextual sub-theory (creative intelligence) Adaptation Shaping Selection The experiential sub-theory (practical intelligence) Novelty Automation

41 Conclusion Intelligence is measured through standardised performance tests (require participants to identify correct solution to cognitive problems) Tests originally designed to predict school & military performance Tests have also shown to be valid predictors of wide range of real-life outcomes. Well-established IQ tests have good reliability & validity

42 Conclusion Debate about structure of intelligence, with some viewing it as a general factor (e.g. g ) Others seeing it as a set of largely independent, more specific abilities Hierarchical models recognise existence of both general & specific factors Consensus on two major aspects of intelligence: fluid (gf) & crystallised (gc) intelligence

43 References Ashton, M. (2007). Individual Differences and Personality. Academic Press. Chamorro-Premuzic, T. (2008). Personality and Individual Differences. BPS Blackwell Chamorro-Premuzic, T. & Furnham, A. (2004). A possible model to understand the personality-intelligence interface. British Journal of Psychology, 95, Maltby, J., Day, L., & Macaskill, A. (2006). Personality, Individual Differences and Intelligence. Prentice Hall.