Lothian Birth Cohorts

The Scottish Mental Survey of 1932

The foundation of the Lothian Birth Cohort 1921 study is a national survey of general intelligence conducted in Scotland in 1932. The participants who were recruited for the study at the University of Edinburgh in 1999 had taken part in the Scottish Mental Survey of 1932. This page summarises the Survey's unique history, aims and findings.

Assessing Scotland's future with a national survey of intelligence

In 1932 the Scottish Council for Research in Education conducted a unique survey to test the intelligence of all children born in 1921 and attending schools in Scotland on June 1, 1932.

The objectives of the Survey were to discover the rates of mental deficiency in Scotland and to obtain information about the distribution of intelligence throughout the community.

This massive exercise was Scotland's contribution to the International Conference on Examinations, funded by the Carnegie Corporation and the Carnegie Foundation, and the International Institute of Teachers College at Columbia University.

Unique school tests of general intelligence

1932 Scottish Mental Survey

The Scottish Mental Survey was a special test designed by Professor Godfrey Thomson, Educational Psychologist at the University of Edinburgh from 1925 to 1951. Professor Thomson was a strong advocate of comprehensive education for all children, regardless of their social status.

The test is known as the Moray House Test No. 12. It had 71 items, eight practice items and two short picture tests, designed for the children who found the Moray House Test too difficult. The highest score to achieve on the test was 76.

Almost all schools in Scotland participate

About 95% of the available, 1921-born population was tested. A few private schools did not take part as well as individual schools that did not receive test papers and others that received too few.

Intelligence test data were obtained for 87,498 children: 44,210 boys and 43,288 girls.

Scotland is the only country ever to have tested an entire year-of-birth in its population.

Estimating general intelligence

The Moray House Test did not give IQ estimates. Therefore, in the summer of 1932, a subsample of 1,000 pupils was given the Stanford Revision of the Binet Intelligence Scale. This sample is often referred to as the Binet 1000. The attempt was to make this 1,000 as representative of the Scottish 11-year-old population as possible, by sampling all educational areas.

In the end, 847 children born between April and July 1921 were tested on the Binet. The Moray House Test correlated about .8 (.81 in the boys, .78 in the girls) with Stanford–Binet scores, providing validity for the Moray House Test.

Further reading about the Scottish Mental Survey of 1932

Deary, I. J., Whalley, L. J., & Starr, J. M. (2009). A lifetime of intelligence: follow-up studies of the Scottish Mental Surveys of 1932 and 1947. Washington, DC: American Psychological Association.

  • Chapter 1 of this book describes the history of the Scottish Mental Survey of 1932 and summarises its results.

Scottish Council for Research in Education. (1933). The intelligence of Scottish children: A National Survey of an age-group. London: University of London Press.

  • This is the detailed account of the results of the Scottish Mental Survey 1932 by the education council who organized the Survey and analysed and wrote up the results.

Watch a video of exhibition ‘Godfrey Thomson: the man who tested Scotland’s IQ’ with Professor Ian Deary’s commentary