Path: utzoo!mnetor!uunet!husc6!mit-eddie!ll-xn!ames!claris!apple!grady
From: grady@Apple.COM (Grady Ward)
Newsgroups: sci.psychology
Subject: Intelligence and IQ tests
Message-ID: <7742@apple.Apple.Com>
Date: 21 Mar 88 03:23:46 GMT
Reply-To: grady@apple.UUCP (Grady Ward)
Organization: Apple Computer Inc, Cupertino, CA
Lines: 87

From "The Structure and Measurement of Intelligence" by Hans J. 
Eysenck, Ph.D., D. Sc. and David W. Fulker, Ph.D.  (University of 
London, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London 
SE5 8AF) Springer-Verlag 1979, pp. 227-228 (Epilogue):

It is possible, and may be useful, to pull together the major conclusions to 
which the research summarized and surveyed in this book may lead us.  
These conclusions are of course not final verities, never to be challenged; 
they are simply points of view, concepts and generalizations which are 
supported by the existing evidence, but which might be disproved by 
experiments in the future.  Taking into account this uncertain status (which 
of course is shared to a greater or lesser degree by all scientific findings), 
we may list our major conclusions as follows:

1.  Cognitive, intellectual performance can be described objectively in terms 
of concepts like abilities, intelligence, etc.

2.  It is possible to measure these concepts empirically, through the use of 
tests, problems, and questions, and indirectly through psychophysiological 
measures.

3.  The intercorrelations between special types of tests define certain 
primary mental factors, usually referred to as primary or group factors.

4.  Primary abilities correlate together to form higher order concepts, such 
as fluid and crystallized intelligence; these concepts are defined in terms of 
observed correlations.

5.  Underlying such higher order concepts as "intelligence" there are 
physiological structures, such as those giving rise to individual differences 
in evoked potentials.

6.  Among major primary factors or abilities thus far demonstrated by 
research are verbal ability, numerical ability, memory, perceptual ability, 
divergent ability, reasoning, visio-spatial ability, and several others.

7.  The IQ, as measured by standard tests, can be shown to be a product of 
the three major independent factors; mental speed, persistence, and error 
checking mechanisms.  This "splitting" of the IQ suggests more analytical 
research designs than have been customary hitherto.

8.  Intelligence as measured by IQ tests has a strong genetic basis; genetic 
factors account for an estimated 80% of the total variance, although this 
estimate has a standard error of some 5% to 10% attached to it.

9.  Intelligence as measured by IQ tests is markedly affected by 
environmental factors; such factors account for an estimated 20% of the total 
variance, but this estimate too is of course subject to a sizeable standard 
error.

10.  Genetic factors in intelligence are largely additive, but with a 
demonstrable contribution from assortative mating and dominance,  This 
accounts for the fact that the broad heritability is some 10 points higher than 
the narrow heritability.

11.  Primary abilities, when the influence of general intelligence is removed, 
also show evidence of genetic determination, sometimes with sex linkage 
(visuo-spatial ability) suspected.

12.  Intelligence, as measured by IQ tests, is related to social behaviours, 
especially as evidence in educational achievement, determination of social 
class, and income (earnings).  These in turn show evidence of genetic 
determination, mediated in part through differences in intelligence.

13.  The facts summarized above lead to a definition of general intelligence 
as general, inherited mental ability; IQ tests measure this ability only with a 
certain degree of inaccuracy, being influenced to a variable extent by 
environmental factors.

14.  The paradigm here outlined is entirely quantitative and scientific; there 
has been no attempt to deal with the so-called humanistic and other 
idiographic (subjective) ways of attacking the problem.  Approaches such as 
Piaget can easily be accommodated within the present scheme.

15.  The concepts used in this book are human inventions, like all scientific 
concepts; they are abstractions which cannot be said to exist or not to exist.  
Concepts are useful or useless; they cannot be true or false.  It is only by 
this criterion that the theories here discussed should be judged.

(This work is subject to copyright.  "Fair use," as defined by the 1976 
Copyright Act, is claimed.)

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If anyone has facts to dispute the above claims, please cite them.  Thank you.

--Grady Ward