Pharmacogenetical Selection

Abstract

In psychology, and in genetics itself for that matter, much effort has been put into selective breeding as a technique for the study of inheritance. Tryon’s deservedly famous psychogenetic experiment of the 1920s and 1930s in which rats were selected bidirectionally for speed of acquisition of maze learning led to the foundation of the Tryon maze-bright and maze-dull strains, now known as TMB and TMD, respectively, descendants of which are still in use, as we shall see. However, while the process of selection itself is valuable both for the demonstration of the importance of genetic influences that a successful selection experiment provides and for the utility in other respects of the resultant strains—usually two—which emanate from it, it is not especially well suited to the fine-grain analysis of genetical and environmental determinants of the phenotype of interest and of their possible interaction. More efficient techniques are available in the study of established strains and the crosses between them, though such strains may, of course, themselves be the product of behavioral, or other, selection experiments. Moreover, “efficiency” here specifically includes the amount of effort involved in addition to the accuracy of the analysis, for selective breeding is an arduous and lengthy technique involving a considerable investment of resources over a relatively prolonged period.