BY DAVID WECHSLER

HISTORYAlfred Binet was a French psychologist who

developed the first IQ test Binet-Simon Scale, then Stanford-Binet Intelligence Scale soon became the standard intelligence test used in the U.S.

The next development in the history of intelligence testing was the creation of a new measurement instrument by American psychologist David Wechsler.

INTRODUCTION

The WAIS-R extends the line of test development that begin with the publication the Wechsler Bellevue intelligence scale in 1939, and continued with it revision, the WAIS published in 1955.

WHAT INTELLIGENCE TEST MEASURES?They are design to measure major mental abilities.

• The concept of global intelligence?WAIS-R test develop to asses all abilities in human e.g. vocabulary, information, picture completion etc.

Organization of scale

VERBAL SCALE

Total 1995 WAIS

Sustainably modified

New

Information 29 20 0 9

Digit span 14 14 0 0

Vocabulary 35 33 0 2

Arithmetic 14 12 1 1

Comprehension 16 12 0 4

similarities 14 10 1 3

Item content of the WAIS-R

Total 1995 WAIS

Sustainably modified

New

Picture completion

20 14 1 5

Picture arrangement

10 6 0 4

Block design 9 9 0 0

Object assembly

4 4 0 0

Digit symbol 93 90 0 3

PERFORMANCE SCALE

STANDEREDIZATION OF SCALEA stratified sampling plan was adopted to

insure that representative proportions of various classes of adult would be included in the standardization sample.

AgeSexRaceGeographic RigionOccupationEducationUrban/Rural Residence

DERIVATION OF SCORESDevelopment of scoring rules.

Rules for starting and discontinuing tests.

Bonus for fast performance.

Age group

N Verbal scale Performance scale

Full scale

MEAN

SD MEAN

SD MEAN

SD

16-17 200 50.72 12.52 47.37 9.49 98.10 20.47

18-19 200 51.72 12.66 46.92 10.09 98.65 20.99

20-24 200 58.62 13.61 51.14 10.27 109.76

22.09

25-34 300 61.42 15.26 49.89 11.63 111.31

25.27

35-44 250 57.47 15.56 45.26 11.97 102.74

26.12

45-54 250 58.12 14.89 42.09 11.34 100.22

24.66

55-64 160 55.59 14.68 38.19 10.80 93.78 24.05

65-69 160 53.54 15.78 33.81 10.59 87.35 24.81

70-74 160 51.50 14.28 30.62 8.40 82.12 20.85

INTERPERTATION OF IQQuantitative interpretation:

The verbal, performance, and full scale IQ distribution were constructed to have means of 100 and SD of 15 within each of 9 age group.

Classification of intelligence:In using qualitative and diagnostic categories to

describe levels of intelligence it is desirable to assign numerical limits to each category.

Full Scale scores beyond 130 place an individual in the superior or "gifted" range. Scores between 120-129 are classed as "very high." Scores between 110-119 are "bright normal." Classifications of other scores are as follows: 90-109, average; 85-89, low average; 70-84,

borderline mental functioning, @50-69, mild mental retardation; 35- @49, moderate retardation; 20-34, severe retardation; below 20 to 25, profound retardation.

Properties of scaleReliability :

The reliability of a test refers to the accuracy of its measurements or put another way to the extent of agreement between score obtained from two or more administrations of the tests to the same subject.

Two types of data are offered Reliability coefficients Standered error of measurements

Properties of scaleValidity :

The initial evidence of the validity of the Wechsler Adult scales stems from the procedures used to determine the content of the original W-B scale.

GENERAL TESTING CONSIDRATIONRange of applicationStandard proceduresPhysical conditionsTesting timeRapportGeneral directions for administrationTiming the itemsProbing of responses

PrecautionsIntelligence testing requires a clinically

trained examiner. The Wechsler scales should be administered, scored, and interpreted by a trained professional, preferably a psychologist or psychiatrist.

General directions for scoringIf a response is intended to replace an earlier

response, the earlier response should be ignored and the later one scored.

Any spoiled response is scored “0”If two independent answers are given to a

question, the examiner must ask which answer is intended

If a subject gives two or more answers to a questions, non of which spoils the response, the best answer of the group should be scored

The Record formThe WAIS-R record form provides space to

record and score the subject’s responses to the test items, and summarize selected information.

Q _ QuestionDK _ Don’t knowInc _ IncompleteNR _ No response

REFERANCES:http://www.indiana.edu/~intell/

wechsler.shtmlTaylor, M. J. & Heaton, R. K. (2001).

Sensitivity and specificity of WAIS–III / WMS–III demographically corrected factor scores in neuropsychological assessment. Journal of the International Neuropsychological Society, 7, 867– 874.