A classification of natal influences is proposed with a model of their operation. Natal influences affect maternal capacity, maternal load, and maternal efficiency. Since maternal load is increased in twin pregnancy, results of twin studies must be generalized with caution. The method of co-twin control is exemplified by examination of a small…

A critique arguing: (1) that the assumptions underlying the use of intelligence tests are invalid; (2) that findings regarding individual differences can not be generalized to differences between populations; and, (3) that the studies cited as evidence were both incorrectly designed and improperly executed. (JM)

The history of the study of human mental ability is an example of the dialectic in social science between those who interpret data within the framework of existing social inequities and those who look for perspectives that might eventually dissolve inequities. The dedication of Henry Herbert Goddard to a belief in the scientific proof of…

Extensive data on twins, nontwin siblings, siblings separated by adoption, and parent-child similarity indicate that the heritability of intelligence is closer to .50 than to .70. Differences could be due to environmental or genetic changes in the population, or to methodology. (Author/CP)

This issue of the IRCD Bulletin is devoted to commentaries on an article by Arthur R. Jensen on the nature-nurture controversy in a recent number of "Harvard Educational Review." Contents of the Bulletin are comprised of the following: "Education, Ethnicity, Genetics and Intelligence; Jensenism: Another Excuse for Failure to…

This document comprises three presentations made on March 23 at a symposium sponsored by the Southern Regional Council focusing on Human Intelligence, Social Science and Social Policy. The first of the three parts of the document is the text of the principal presentation, made by Dr. Leon Kamin, Chariman of the Department of Psychology at…