Kuhlen, R. S. (1961). Social Change: A Neglected Factor in Psychological Studies of the Life Span. In J. J. Jenkins & D. G. Paterson (Eds.), Studies in individual differences: The search for intelligence (pp. 479-481). East Norwalk, CT, US: Appleton-Century-Crofts.
http://dx.doi.org/10.1037/11491-039
This reprinted article originally appeared in School & Society, 1940, Vol 52, 14-16. (The following abstract of the original article appeared in record 1940-04939-001.) The decrease in IQ with age may be in part attributed to social change which cannot be adequately evaluated by the usual comparison of age groups. Older people of today had fewer opportunities for education and recreation. The effect of automobiles, radios and movies is hard to evaluate. A school year today is not the equivalent of a school year twenty years ago. Only when the same groups are retested at different ages, or when careful analysis is given to individual test items which would be affected most by social change, can one be sure how far the observed decrease in IQ is dependent on age itself. (PsycINFO Database Record (c) 2016 APA, all rights reserved)