‘Much more at home with 3.999 pupils than with four’1: The contributions to psychometrics of Sir Godfrey Thomson

Abstract

Godfrey Thomson's writings cover many areas of psychology, education and statistics but the most influential aspects of his work were at the interfaces between these three fields. His work revolved around the concept of intelligence: its nature, how to measure it, how far it was genetically determined and whether on average it was increasing or decreasing in society over time. His earlier work on the factorial nature of intelligence was dominated by a debate with Charles Spearman, who promoted the notion of general intelligence not only as one explanation of test data but as the only permissible explanation. It was this claim of uniqueness which Thomson contested. Initially the debate was conducted in terms of alternative competing theories but subsequently it was overtaken by the development of factor analysis as a statistical technique and a recognition that the debate concerned the merits of different methods of analysing data rather than deciding empirically between mutually exclusive theories. Thomson's views on the role which selective tests should play in education are contrasted with the role which he did play as the author of the Moray House tests, which were widely used by education authorities throughout Britain. The development of these tests enabled Thomson to collect data to show that larger families score lower on standardised tests, suggesting that there might be a long‐term decline in national intelligence. His role in the 1932 and 1947 Scottish Mental Surveys illustrates his concern with this possibility, though the surveys did not produce evidence of any such decline.