Path: utzoo!utgpu!water!watmath!watdragon!dahlia!rmpinchback
From: rmpinchback@dahlia.waterloo.edu (Reid M. Pinchback)
Newsgroups: sci.psychology
Subject: Re: Intelligence and IQ tests
Message-ID: <6298@watdragon.waterloo.edu>
Date: 8 Apr 88 19:54:56 GMT
References: <7742@apple.Apple.Com>
Sender: daemon@watdragon.waterloo.edu
Reply-To: rmpinchback@dahlia.waterloo.edu (Reid M. Pinchback)
Organization: U. of Waterloo, Ontario
Lines: 68

In article <7742@apple.Apple.Com> grady@apple.UUCP (Grady Ward) writes:
>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):
>
... stuff
>3.  The intercorrelations between special types of tests define certain 
>primary mental factors, usually referred to as primary or group factors.
>
... more stuff
>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.
>
.... more stuff
>If anyone has facts to dispute the above claims, please cite them.  Thank you.
>
>--Grady Ward


   Most of it is in the form of neutral commentary, and critical analysis of
an informal literature review 9 years old isn't too meaningful.  To dispute 
empirical evidence in psychology (as in most sciences) generally requires
examination of the original work (including nasty unpublished details that
researchers tend to leave out).

   Having said that, the figures quoted (80/20 split on nature/nurture),
are, I believe, the WITHIN groups differences.  They aren't the BETWEEN groups
difference figures.  Comparing groups that differ in culture, sex, race,
geographic location, etc., is a process that has come under attack, unless
the relevant distinction is made.  Thus a variable like inheritance is better
at explaining IQ differences between your brother/sister and your cousins, 
than it is for explaining black/white IQ differences.  The role of inheritance
in explaining between-groups differences appears to be a much weaker one than
it is for within groups.

   So, in particular, comment (12) is somewhat questionable.  Literature
references are Layzer[72], Lewontin[76], Loehlin, Lindzey & Spuhler[75],
Scarr & Carter-Saltzman[82].  At this point in time, research results seem to
be equivocal.  Many confounds have been proposed.  Perhaps a comprehensive
review has been done more recently to include the results of recent research,
I don't know.  Maybe somebody out there in netland does.




     Reid M. Pinchback
     -----------------