Presentation on theme: "Intelligence Testing: Psychology’s Most Important Contribution? Perhaps Psychology’s Most Familiar Contribution. Certainly Not Psychology’s Most Important."— Presentation transcript:
Intelligence Testing: Psychology’s Most Important Contribution? Perhaps Psychology’s Most Familiar Contribution. Certainly Not Psychology’s Most Important Scientific Contribution. Boring - Intelligence Is What An Intelligence Test Measures. Piaget - Intelligence Is The Ability To Benefit From Experience.
Galton’s Laboratory for Measuring Intelligence (apparatus for testing absolute and differential threshold)
Origins of Intelligence Testing Galton: Looked for a correlation between acuity of the senses and intelligence (colloquially defined) Alfred Binet and Theodore Simon (1905, 1908 and 1911): How could they identify young Parisian school children who could benefits from different levels of instruction? Validating procedure was performance at school. These schools placed heavy stress on certain traditional areas. Still unclear to what extent an intelligence test is measuring ability to perform in a manner heavily reinforced by certain segments of society as opposed to true intellectual ability.
Binet’s procedure Construct different types of items, e.g., vocabulary, reading comprehension, reasoning, etc. Determine which items can be passed by X% of the population (Binet: X = 60%; currently, X = 50%). Equivalent of asking, “what can an average 6, 7, 8, etc. year-old do?” Use novel items so that the test measures aptitude rather than achievement. –Example: Mark F if the sentence is foolish, mark S if it is sensible: S F Mrs. Smith has had no children and I understand that the same was true of her mother.
Mental age Concept introduced by Stern. Each subtest (arithmetical, memory, vocabulary, spatial relations, etc.) contains items of graded difficulty. Examples: Year II –*Place simple blocks properly in 3-hole foam board. –*Identify models of common objects such as a cup by their use. –*Identify major part of a doll’s body. –*Repeat two digits. Year III –*Child is given 48 beads and a shoestring. He must thread beads on the string. –*Child is given twelve 1-inch blocks. He must make a bridge out of three of them. Year VI –*Child is given a card with mutilated pictures. He must name the parts that are missing. –*Child is given twelve 1-inch blocks. He must hand the examiner the number of blocks he asks for. Year VIII –*Two objects such as baseball and orange are named. The child must say in what way they are alike and different. –*A short paragraph is read to the child who must then answer simple questions about it.
Calculating Mental Age Performance on each part of the test is averaged for children of a particular age to obtain a norm for that age. The more subtests a child passes, the higher the child’s mental age. Mental age is the age level at which the child gets 50% or fewer items correct. Mental age is obtained independently of chronological age, which is the child’s actual age in years. Stern’s measure of IQ: IQ = 100 x MA/CA A bright child is one who exceeds the norm for her age level. A dull child is one who falls below the norm.
Examples of Test Items from Stanford-Binet Year II 1. Place simple blocks properly in 3-hole foam board. 2. Identify models of common objects such as a cup by their use. 3. Identify major part of a doll’s body. 4. Repeat two digits. Year III 1. Child is given 48 beads and a shoestring. He must thread beads on the string. 2. Child is given twelve 1-inch blocks. He must make a bridge out of three of them.
Year VI 1. Child is given a card with mutilated pictures. He must name the parts that are missing. 2. Child is given twelve 1-inch blocks. He must hand the examiner the number of blocks he asks for. Examples of Test Items from Stanford-Binet Year VIII 1. Two objects such as baseball and orange are named. The child must say in what way they are alike and different. 2. A short paragraph is read to the child who must then answer simple questions about it. Year X 1. The child is asked to give reasons to questions such as: “Give two reasons why children should not be too noisy in school.” 2. The child is asked to say as many words as he can in a one-minute period.
Hearings before the Committee on Immigration (cont’d) This is the most important book that has ever been written on this subject...Col. Robert M. Yerkes...vouches for this book, and speaks in the highest terms of Prof. Carl C. Brigham, now assistant professor of psychology in Princeton University. This comes as near being official United States Army data as could well be had...they had two kinds of tests, alpha and beta....They took the greatest care to eliminate the advantage which native Americans would otherwise have had....
C. C. Brigham, A Study of American Intelligence. Princeton: Princeton University Press, 1923. The Nordics are...rulers, organizers, and aristocrats... individualistic, self-reliant, and jealous of their personal freedom...as a result they are usually Protestants....The Alpine race is always and everywhere a race of peasants...perfect slave(s), the ideal serf... unstable temperament…and reasoning power so often found among the Irish...our army sample of immigrants from Russia is at least one half Jewish....Our figures, then, would rather tend to disprove the popular belief that the Jew is intelligent...he has the head form, stature, and color of his Slavic neighbors. He is an Alpine Slav [pp. 182-3. 185, 189, 190 from Brigham].
Hearing before the Committee on Immigration, United States Senate, February 20, 1923, (Washington, Government Printing Office, 1923), pp.80-81. We have been overrun with a horde of the unfit....we have had no yardstick....The psychological tests...furnished us with the necessary yardstick....The Army tests...revealed the intellectual endowment of the men....The tests are equally applicable to immigrants....All that is required is a staff of two or three trained psychologists at each port........ See Memoirs of the National Academy of Sciences....We can not be seriously opposed to immigrants from Great Britain, Holland, Canada, Germany, Denmark, and Scandinavia....We can, however, strenuously object to immigration from Italy... Russia...Poland...Greece... Turkey.... The Slavic and Latin countries show a marked contrast in intelligence with the western and northern European group....One can not recognize the high-grade imbecile at sight....
Hearings before the Committee on Immigration (cont’d) They think with the spinal cord rather than with the brain....The necessity of providing for the future does not stimulate them to continuous labor....Being constitutionally inferior they are necessarily socially inadequate....Education can be received only by those who have intelligence to receive it. It does not create intelligence. That is what one is born with....The D minus group can not go beyond the second grade....we shall degenerate to the level of the Slav and Latin races...pauperism, crime, sex offenses, and dependency...guided by a mind scarcely superior to the ox.......We must protect ourselves against the degenerate horde....We must view the immigration problem from a new angle....We must apply ourselves to the task with the new weapons of science...the perfect weapon formed for us by science....it is now as easy to calculate one ‘s mental equipment as it is to measure his height or weight. The examination of over 2,000,000 recruits has tested and verified this standard....this new method...will enable us to select those who are worthy and reject those who are worthless.
Hearings before the Committee on Immigration and Naturalization, House of Representatives, January 3, 4, 5, 22, and 24, 1923, (Washington, Government Printing Office, 1923), pp.589-594. to further restrict immigration from southern and eastern Europe...[since] the evidence is abundant...that...it is largely of a very low degree of intelligence....A large proportion of this immigration...consists...of the Hebrew elements...engaged in the garment-making industry....some of their labor unions are among the most radical in the whole country....The recent Army tests show...the intelligence of the Italian immigration...is of a very low grade, as is also that of the immigration from Poland and Russia. All...rank far below the average intelligence for the whole country.
EXAMPLES OF ITEMS FROM WECHSLER-BELLEVUE TEST (VERBAL) Information: (experience and education) Easy: How many ears do you have? Hard: Why does oil float on water? Very hard: What is a lien? Comprehension: (Practical knowledge and social judgment) What should you do if you cut your finger? Why do we elect senators and congressmen? Arithmetic: (Concentration and arithmetic reasoning) How many pieces result when you cut an apple in half? If a taxi charges 50¢ first 1/5 mile, 15¢ each additional 1/5, how much for a two mile trip? Similarities: (Logical and abstract thinking) What is similar about a plum and a peach? About 49 and 121? Digit Span: (Attention and rote memory) Repeat 5 4 6 7 4 3 2 6 Vocabulary: (Word knowledge) Define: Diamond, Belfry, Traduce
EXAMPLES OF ITEMS FROM WECHSLER-BELLEVUE TEST (NON-VERBAL) Picture completion: (visual alertness and visual memory) woman with mouth missing, scene with tree without shadow Picture arrangement:(Interpretation of social situations) cartoons Block Design: (Analysis and formation of abstract design) match by synthesis a geometrical form Object Assembly: (Putting together of concrete forms) jig saw puzzles Coding: (Speed of learning and writing symbols) substitute symbols for letters, e.g. Y = 3, D = 4 Mazes: (Speed of learning and writing symbols) draw path through a maze
Culture-free tests Question 1: Pick out one item that does not belong with the others: cello hay drum violin guitar Question 2: Find the three things which are alike in each list: store banana basket apple reed plum
IQ and Competence IQCOMPTETENCE REPRESENTED 130Mean of persons receiving Ph. D. 120Mean of College Graduates 115Mean of freshmen in typical first year college Mean of children from white-collar and skilled labor homes 110Mean of High School graduates Has a 50 - 50 chance of graduating from college 105About 50 - 50 chance of passing in academic H. S. curriculum 100Average for total population
IQ and Competence (cont’d) IQCOMPTETENCE REPRESENTED 90 Mean of children from low income city homes or rural homes. Adult can perform jobs requiring some judgment (operate sewing machine, assemble parts) 75Adult 50 - 50 chance of reaching High School 60Adult can repair furniture, harvest vegetables, assist electrician 50 Adult can do simple carpentry, cosmetic work Adult can mow lawns, do simple laundry
Distribution of IQ Scores IQ% of adults 130 2.2 120-129 6.7 110-11916.1 90-10950.0 80- 8916.1 70- 79 6.7 less than 70 7.2
Validation of Stanford-Binet IQ and reading comprehension0.73 IQ and reading speed0.43 IQ and English usage0.59 IQ and history0.59 IQ and biology0.54 IQ and geometry0.48
SAMPLE SUBJECT FROM TERMAN STUDY A. Successful Subject Subject A792 graduated from high school at 16, from college at 20, with Phi Beta Kappa honors, and received his Ph. D. in science at 23. In his undergraduate college years he earned a quarter of his expenses and in his graduate years supported himself entirely. He was then awarded a National Research Fellowship for post-doctoral study, after which he was appointed to a position in a leading university. By the age of 40, he was nationally eminent and director of a great scientific laboratory. He is listed in American Men of Science and Who’s Who.
SAMPLE SUBJECT FROM TERMAN STUDY B. An Unsuccessful Subject Subject C49 had almost exactly the same I.Q. rating as A792, also had a superior record through high school, and in college earned about the same proportion of his expenses. There the similarity ends, for C graduated from college well below the average of his class. After graduation he drifted for several years, then returned to college and managed to complete his work for a master’s degree. His occupations since then have ranged from semiskilled labor and clerical jobs to positions of minor responsibility in business organizations. His chief handicaps have been inferior social adjustment, uncertainty with respect to life goals and lack of drive or persistence. As a result he has accomplished less than the average college graduate.
Validity of IQ Tests Correlates 0.30-0.60 with grades. Poor predictor of achievement out of school. Best predictor of professional achievement is socioeconomic status of parent.
Is Intelligence Heritable? In 1923, ETS administered the Binet test to a large group of immigrants and found the following percentages of their sample to be feeble minded. 83%Jews 80%Hungarians 79%Italians 87%Russians
MEAN CORRELATION COEFFICIENTS FOR IQ, FOR VARIOUS CATEGORIES OF PAIRS OF RELATIVES Type of relationship# of separate studies # of pairs of relatives Mean Correlation Coefficient Identical twins raised apart3650.72 Identical twins raised together 3446720.86 Same-sex fraternal twins raised together 2936700.62 Opposite-sex fraternal twins raised together 1815920.57 Non-twin siblings raised together 69264730.47 Unrelated (adopted) siblings raised together* 117130.30 * This category consists of sibling pairs in which either one or both members were adopted and genetic relationship was zero.
Herrnstein’s syllogism: We live in a meritocracy. IQ is heritable. If e 2 decreases, h 2 must increase. (Beware! Improving education, reduces e 2.)
How to Reduce h 2 1.Interbreed - this reduces 2 2. Increase 2 e. How to Increase h 2 1.outcrossing - new genes 2. mutation - new genes 3.select for rare characteristics 4. reduce 2 e.
Three Classes of Minority Groups Autonomous minorities- Deliberate separation from mainstream. Proud of heritage, e.g., Amish. Involuntary minorities- Did not choose their minority status. Routinely judged as inferior by dominant majority, e.g., blacks in North America, Buraku in Japan, Harijans (untouchables) in India. Immigrant minorities- Hope to better themselves in accordance with their traditions.
Example of Effect of Membership in an Involuntary Minority Ogbu (Japanese minority) Have a caste-like status in Japan. Culturally, not racially, distinct. Average IQ score 10-15 points lower than dominant majority in Japan. No difference in the United States.
How does IQ change with time, say, from 1920-2003? IQ Scores time IQ Scores time IQ Scores time