Some history of a methodological rediscovery.

Comments on the article by S. M. Kosslyn et al (see record 2002-12932-001). The article extended to biopsychological research an important principle the authors traced to B. J. Underwood (1975): Systematic study of individual differences in a relationship between two or more dependent and independent variables can contribute greatly to the extension of psychological theory. R. R. Holt calls attention to several earlier discoveries of the same point. (PsycINFO Database Record (c) 2010 APA, all rights reserved)