Intelligence Tests

Binet-Simon Scale - first intelligence test, developed by Alfred Binet (and Simon).

Individually administered comprehensive tests (Stanford, Wechsler (3), KABC): 1. One on one administration takes about 60 - 90 min. Therefore, expensive. Actually consist of sets of "subtests" grouped into theory based "areas."

2. Training and practice are necessary. Strict protocols such as no "hints" or "coaching." Some subtests require "timing" with a stopwatch.

3. While a licensed psychologist must interpret and write the report, administration can be done by others.

4. Very reliable, in the .90 range.

5. Most often used with school age children.

6. Often paired with an achievement test to form a "test battery."

7. Use some type of "adaptive format" to avoid administering unnecessary items.

8. Deviation IQ - used in modern tests (in place of Terman's IQ "formula") and credited to David Wechsler. IQ is based on "normative data tables" and provides a more accurate measure. l. Stanford Binet - developed by Lewis Terman at Stanford Univ. Subtests reflect Raymond Cattell's "fluid vs. crystallized" intelligence theory plus short term memory. Ages 2 - adult.

1. Most widely used until surpassed by the Wechsler tests in mid-1900s.

2. Comprehensive behavioral checklist.

3. Fifteen subtests total (combination varies by age).

4. Vocabulary is used as the "routing" test which determines "starting levels" for remaining subtests (levels are lettered A, B, C, etc.).

5. basal level (age) - level at which 3 of 4 consecutive items are passed (starting point).

6. Ceiling level (age) - level at which 3 of 4 consecutive items are missed (stopping point). 7. Raw scores are converted to "Standard Age Scores" (SASs). Subtests are summed to yield 4 "area" scores: 1. verbal reasoning, 2. abstract/visual reasoning, 3. quantitative reasoning, 4. short-term memory, and finally a test composite (IQ) mean = 100, SD = 16 (most tests are 15).

8. Large number of subtests and complex "basal-ceiling-lettering" system make it difficult to administer.

II. The Wechsler Tests (3) - David Wechsler saw need for 1. a test designed for adults and 2. a test less "verbally dependent" than the Stanford. Theory wise, Wechsler distinguishes only two areas, "verbal and performance" (though short term memory is clearly represented). There are three tests:

- Wechsler Adult Intelligence Scale (WAIS) - for adults - Wechsler Intelligence Scale for Children (WISC) - for older children and adolescents. - Wechsler Preschool and Primary Scale of Intelligence (WPPSI) - for young children.

1. Each test contains only the subtests needed and all subtests are used.

2. Starting points are based on age. Subtest is stopped when a specified number of consecutive items are missed.

3. Rather than being keyed to "age" the items use a simpler "point" system (items vary in point value). "Time" (rapid completion) is also worth points).

4. Raw scores are converted to standard scores with a mean of 10 and SD of 3.

5. Raw scores are also added to yield two area scores ("Verbal" and "Performance") and an overall IQ. All have a mean of 100 and SD of 15.

6. Currently, the most popular intelligence tests.

III. Kaufman Assessment Battery for Children (KABC) - contains both "mental processing" (IQ) AND "achievement" scales. Theory involves a novel distinction, "Sequential" vs. "Simultaneous" processing.

1. It yields four "Global Scores": 1, sequential processing, 2. simultaneous processing, 3. mental processing composite (IQ), and 4. achievement.

2. Like the Wechsler, the scales have a mean of 100 and SD of 15.

3. Makes extensive use of "confidence intervals" in reporting scores. 4. Reports "significant differences" in the global scores.

5. A "non-verbal" set of scales make it ideal for use with hearing or speech impaired children.