Intelligence

• A concept that refers to individual differences in abilities to: – Acquire knowledge – Think and reason effectively – Deal adaptively with the environment

The Psychometric Approach to Intelligence

• Psychometrics: the statistical study of psychological tests • The g factor (Spearman, 1923)

– Intelligence performance governed by: • General intelligence (g) • Specific abilities

• Thurstone’s primary abilities – Intelligence performance governed only by specific abilities

Theories • Spearman’s g factor (1904) - a theory of general intelligence termed g • G is a kind of mental energy which flows into everything a person does • A person who is good at mathematics is probably also good at reading

comprehension, has a wide vocabulary, etc. • Thus g or general intelligence is a type of mental energy which allows one to

be consistently good or poor at a variety of different tasks Spearmans

• In addition to g Spearman also proposed that there were special abilities termed s

• S is the mental energy specific to a particular task • Therefore if you are good at math it is a combination of g and s • S is necessary to account for variability across tasks (better at some than

others) Theories Cont

• Thurstone’s (1938) Primary Mental Abilities • Seven Primary Mental Abilities • 1 Spatial visualization 2 Perceptual Speed • 3 Numerical 4 Verbal Meaning • 5 Memory 6 Word Fluency • 7 Reasoning

Thurstone • Abilities are viewed as relatively independent of one another • I.e., a person high in spatial ability maybe low in verbal meaning • Although more expansive than Spearman’s theory it is not incompatible with

it • Task analyses led Thurstone to believe these seven abilities were required • Many if not most activities require more than one primary ability • E.g., Reading – requires – verbal meaning, word fluency, memory and

reasoning

Theories Cont • Guilford’s (1961) Structure of Intellect • Recall Spearman’s g & s • Thurstones 7 Primary Mental Abilities • Guilford’s model proposed 120 factors • 3 Basic: 1 Operations (act of thinking) • 2 Contents (terms of thinking –words, symbols) • 3 Products (ideas we come up with)

Guilford • Within each basic category there are several sub factors • Operations • Are composed of cognition, memory, divergent thinking, convergent thinking

& evaluation • Contents • Are composed of figural, symbolic, semantic, behavioral • Products • Composed of implications, transformations, systems, relations, classes &

units • Guilfords model is conceived of as a three dimensional matrix • He postulates that at least one sub-factor from each category is

present/necessary to perform a task • E.g., Reading involves semantics (contents) cognitive, memory, evaluation

(operations) relations, implications (products)

Theories Cont • Burt-Vernon Theory of Intelligence • Hierarchical Theory • Thus unlike Thurstone or Guilford the abilities are NOT viewed as

independent but rather certain abilities are nested within others

The Cognitive Approach to Intelligence

• Sternberg’s triarchic theory of intelligence

Theories Cont • Jensen’s Level I & Level II Theory • Arthur Jensen argued that existing theories were overly complex (Guilford?) • He proposed that all tasks could be measured based upon the degree to

which they required Level I and Level II abilities Jensen

• Level I is composed of simple rote memory • No intentional or conscious transformation of input prior to output (e.g.,

serial recall) • Level II is composed of complex mental abilities • Input requires conscious transformation prior to output (e.g., recall list in

categories) • In this approach Intelligence would be measured on the basis of the types of

tasks completed • The more tasks completed correctly requiring complex abilities the higher a

person’s intelligence would be rated • Eg., in a multiple choice exam questions can be rated 1) Factual, 2)

Comprehension, & 3) Higher order • Regardless of the IQ test employed higher IQ test takers should not only get

more questions correct they should get more of types 2 & 3 correct Assessment of Intelligence

• Classical Assessment • Psychometric approach • These include Stanford Binet, WAIS, MAB, Raven’s matrices, Porteus Mazes, • Binet scales were developed to originally provide assessment of children in

France for the purpose of identifying those in need of remedial education • First scale – the Binet-Simon scale was issued in 1905. Became Stanford-

Binet when revised for North America at Stanford University by Terman • 30 tests arranged in order of increasing difficulty – child continued until a

series of consecutive wrong answers were obtained • Repeated testing across many different children revealed that at a given age

the majority of children got approx the same number of questions correct –a few got less and a few got more

• This led to the first normative data set for performance comparison • In 1908 Binet introduced the concept of Mental Age (MA). William Stern

(1916) indicated how it could be used in conjunction with chronological age (CA) to produce an Intelligence Quotient

• Mental age is based upon the level of tasks completed by a normal group of children at a given chronological age

• If a child completes the tasks normally done by children at age 8 CA then regardless of that child’s actual CA their Mental Age is deemed to be 8

Binet’s Assumptions

– Mental abilities develop with age

– The rate at which people gain mental competence is characteristic of the person and is constant over time

Stern’s Intelligence Quotient IQ = MA x 100 CA Stern’s formula: IQ = (MA/CA)*100

• Thus if a child completes the tasks common to children 8 years CA and is him/her self 8 years CA the IQ = 100

• If the child completes the tasks commonly completed by 10 year CA but is 8 years CA the IQ = 125

• If the child completes the tasks commonly completed by a 6 year CA but is 8 years CA the IQ = 75

Types of Tests

• Achievement Tests • Designed to discover how much someone knows

• Aptitude Tests • Measure potential for future learning and performance

Weschler Adult Intelligence Scale

• This was the first Adult intelligence test (Weschler, 1939) • The test is divided into two parts which roughly correspond to the divisions

proposed by Burt & Vernon • Verbal & Performance • Each have 4 subsets of test items

Verbal

• Vocabulary • Simple arithmetic • Information • Judgment

Performance • Block design • Incomplete pictures • Puzzles • Pictures to arrange as a story

• Test produces multiple scores • A score for each subtest • An aggregate score for each major section • Overall IQ score

Multi – Dimensional Aptitude Battery (MAB) Douglas Northrop Jackson II 1929 - 2004

• MAB (Jackson, 1983) • IQ measures on this test correlate r=.91 with those from the WAIS-R • Advantage is that it is entirely paper & pencil • This allows for the testing of multiple persons simultaneously a huge cost

advantage for users • Also split into 2 sections – Verbal & Performance • Each section has 5 subtests vs the 4 in the WAIS

Other Psychometric Approaches to Intelligence

• Cattell and Horn’s Theory – Crystallized intelligence

• Ability to apply previously learned knowledge to current problems

– Fluid intelligence • Ability to deal with novel problem-solving situations without

any previous knowledge

• Garner’s (1983) Multiple Intellegences – There are six relatively independent intelligences

• Linguistic, mathematical, visual-spatial – Tested by current intelligence tests

• Musical, body-kinesthetic, personal – Not tested by current intelligence tests

– Savants : Cognitively disabled people with a striking skill in a specific area, like music or math ability.

• Emotional Intelligence – Ability to read other’s emotions accurately – Respond accurately to them – Motivate oneself – Be aware of one’s own emotions

– Control one’s emotional resonses Controversy

• All of the Classical psychometric tests we have examined up to this point have been subject to the criticism that they have cultural biases

• Two Unique tests have been developed to address this issue • Raven’s Progressive Matrices & Porteus Mazes

Types of Reliability

• Test-retest reliability – Assessed by administering the measure to the same group of

participants twice and correlating scores

• Internal consistency – All of the items of the test should measure the same thing

• Interjudge reliability – Consistency of measurement when different people score the same

test Types of Validity

• Construct – Does a test measure what it is supposed to measure?

• Content – Do the items on a test measure all the knowledge or skills that

comprise the construct? • Predictive

– How well does the test score predict criterion measures? Alternative Assessment Techniques

• Reaction Time (RT) Vernon Assumption is that as RT goes down IQ goes up (I.e., more intelligent persons process information more quickly) This assumption is in line with the assumption upon which speeded items in the classical tests were based Reaction Time & IQ

• Simple RT • Subject holds down button and when detects light releases button RT is time

from start of light to release of button • Decision RT • Subject holds down button, 1,2,4,8 light array & subject must hit button

corresponding to number of lights • Simple RT & Light Decision RT • RT measures are inversely related to performance on classical IQ tests – r = -

.30 (I.e., RT goes down as IQ goes up) • RT goes up as number of lights (bits of information) increase • STM RT • Subjects are presented a digit string then a probe (single digit) task is

whether probe was in original string • RT goes up with string size • RT goes down with higher IQ • That is r = -.42 to -.62 for RT & IQ • Speed of retrieval from LTM • Task is to make judgments (same or different) about pairs of letters on either

semantic or physical dimensions • Semantic: AA or Aa Physical: AA or AB.

The difference between the RT for Semantic versus Physical = Speed of Retrieval from LTM. The differences are smaller for those who have higher IQ

• Does Intelligence affect the speed of word recognition? (Biggs, Mui, & Mori, CPA Convention, 1988)

• Two tasks utilizing the Priming paradigm • Stimulus 1 is either related or unrelated to the target (Stimulus 2) – When

related it “primes” the target by pre-activating semantic information linked to it (I.e., the target)

Biggs, Mui, & Mori (1988) • IQ measured on subsets of MAB (Jackson, 1983) • 2 Verbal - Verbal Comprehension & Verbal Similarities • 2 Performance – Digit Symbol & Spatial • Task 1 NAMING • This task requires only access to the lexical phonemic representation of the

target • Hypothesis 1: Targets related to primes should be responded to more

quickly (the typical “priming” effect). • Hypothesis 2: RT should be quicker for high IQ • Hypothesis 3: Priming effect should be smaller as IQ increases • Task 2 LEXICAL DECISION • This task requires access to the stored lexical pattern in order to determine if

the stimuli is an actual word or if it is merely a pronouncable non-word and then requires a binary (Yes/No) decision.

• Lexical Decision • Hypothesis 1: Targets related to primes should be responded to more

quickly (the typical “priming” effect). • Hypothesis 2: RT should be quicker for high IQ • Hypothesis 3: Priming effect should be smaller as IQ increases • RESULTS • In both tasks Hypotheses 1 & 2 were confirmed (Typical priming effects were

observed & RT’s in all conditions [related vs unrelated] were faster for High IQ subjects (r = -.413)

• Hypothesis 3 was confirmed only for the NAMING task (r = -.25) and NOT for LEXICAL DECISION

• Conclusions • Low IQ persons (as measured on the MAB) benefit more from the “priming”

of targets than do high IQ persons but only in the task which requires simple access.

• This suggests that the benefit of higher IQ is in the speed of access to information as opposed to in the processes of making a decision.

Alternative Assesment

• Electroencephalography (EEG) • Hans Berger (1933) first investigated IQ in relation to EEG • Use recording electrodes on scalp • Stimulated visually, auditorily, & somatosensory • Analysed evoked potentials

Example of an Evoked Potential Recording

Evoked Potential & IQ

Alternative Assesment

• Positron Emission Topography (PET) • First developed in 1950’s • Involves injection of radioactive isotope • Scan Brain to see areas and degree of activity in glucose & oxygen

metabolism • Applications – brain function localization

• Identification of memory impairment PET Scanning

• Scanning during administration of Raven’s • Have found that senile dementia involves lower glucose metabolism in

Frontal Lobes • Have found Alzheimer patients show lower glucose metabolism in Basil

Ganglia • The next slide shows PET scans for various tasks

Brain activity and IQ: Low IQ is on left and High IQ on right. Glucose metabolism indicates Low IQ are using more energy to complete task

Standardization • Must create a well-controlled environment for administering the test • Normative scores (norms) provide a basis for interpreting an individual

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Biology of Intelligence • Intelligence may involve neural efficiency

– There are moderate correlations between IQ and speed and efficiency of information processing in the brain

– PET scans show that brains of highly intelligent people work more efficiently

Biological or Environmental Influences of Intelligence

• Ethnic differences - On average: – Asian-Americans score above white norms – Hispanic-Americans score at white norms – African-Americans score 12-15 IQ points below white norm

Heritability of Intelligence

• Heritability is defined as the extent to which a trait will be exhibited by a population given that the population shares the same environment. (Denoted as h2)

• h2 = how much of IQ is due to genes (perfect score would be 1) • 1 – h2 = how much of IQ is due to environment • Note: h2 does not ignore enviroment it says given 100% same enviroment a

certain level of intelligence will be shown or is predictable. • Twin Studies • h2 = 2(rMZT – r DZT) • Perfect score would be 1 (e.g., h2 =2[1-.5]) • Heritability coefficients on the Multiple Aptitude Battery (MAB) and Simple

Reaction Time (RT) MAB – h2 = .906 Simple RT – h2 = .559 Biology of Intelligence

• Heredity and intelligence Correlations in intelligence Relationship r MZ reared together .86 MZ reared apart .75 DZ reared together .57 Siblings reared together .45 Siblings reared apart .21 Parent-offspring, reared by parent .36 Parent-offspring, not reared by parent .20 Adopting parent-offspring .19 Adopted children reared together .02

Sex Differences in Cognitive Abilities • Males

– Better at spatial tasks – Better at throwing, catching objects – Better at mathematical reasoning

• Females

– Better on tests of perceptual speed – Have better verbal fluency – Better at mathematical calculation – Better fine motor coordination

Intelligence & Personality

• Studied with “gifted” population • Terman (1925) selected 1500 students from Califonia school system with IQ

scores over 135 (Mean IQ was 151) • Followed group throughout life span • Characteristics as Children • Fewer birth defects • Better vision & hearing • Better health • Taller & heavier • Began talking earlier • Higher self esteem • More socially adept as adolescents • Reached puberty earlier • Characteristics as Adults • Average of 1 inch taller • Lived longer than average • Thinking as Children • Found abstract subjects more appealing • Discovered relationships between seemingly unrelated concepts earlier • Higher moral development • More independent • Greater use of mental imagery for problem solving • Achievements • AS a group – published over 2000 scientific papers, 80 scientific books, and

numerous works of fiction • 483 obtained graduate degrees (28 times national average) • 95.8% received University scholarships

Life Satisfaction Reported by Gifted Men & Women in Terman’s Life Spann Study

Data gathered 1972: mean age of subjects 62. Joy refers to overall satisfaction with life. PROJECT Ex. reaction time Test hypothesis of things that will have slower/faster reaction time Show item Record response time Big goal – want to know difference between 2 situations Sub goal – collect information