EDUCATIONAL PSYCHOLOGY 



Intelligence testing is nothing more nor less than a 

 sampling of one's intellectual and behavior responses. 

 Galton likened it to the assaying of mineral ores. The 

 effectiveness of the sampling depends upon: (l) whether 

 it is extensive enough to give consistent results, and (2) 

 whether it is a sampling of intelligence or of something 

 else. If a test is extensive enough to give consistent results, 

 it is said to be reliable. If its verdict correlates fairly well 

 with other criteria of intelligence, the test is said to be 

 valid. 



The reliability and validity of tests cannot be judged 

 by opinion, either the opinion of the layman or of the 

 psychologist. Both have to be experimentally determined. 

 The results of such determinations are expressed in quanti- 

 tative terms, usually correlation coefficients. It has been 

 definitely established that the best of the current intelli- 

 gence tests are reliable in the sense that they give consistent 

 results, and that they are valid in the sense that they 

 discriminate clearly between groups of subjects classified 

 by other reasonable criteria as bright, average, or dull. 

 Whatever misinformed critics may say, the best intelli- 

 gence tests really do measure with greater or less approxi- 

 mation what we may reasonably call intelligence; that is, 

 ability to make complex adaptations, to think in con- 

 ceptual terms, and to solve difficult problems. 



The limitations of intelligence tests must, however, 

 be kept in mind. These are chiefly of three sorts. In the 

 first place, no intelligence test is a test directly of native 

 ability. It tells us what grade of intelligence the subject 

 has when he is tested, not necessarily what he might have 

 had if his education and cultural background had been 

 different. Any judgment about native intelligence is always 

 a matter of inference. My personal judgment is that the 

 experimental investigations to date do not suggest that 

 the scores on the best intelligence tests are very greatly 



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