Tryon's Rat Experiment

[1] Prior to Robert Tryon’s study of selective rat breeding, concluded in 1942, many psychologists believed that environmental, rather than genetic, differences produced individual behavioral variations.

To do so, Tryon created an experiment that tested the proficiency of successive generations of rats in completing a maze.

Tryon continued this process for seven generations, creating two distinct breeds of “bright” and “dull” rats.

In order to demonstrate that behavior had little effect on the genetically selectively bred rats, and lessen the chance of error when making his conclusions, Tryon cross-fostered the rats—that is, he had a “dull” mother raise “bright” children, and vice versa.

[3] Nonetheless, Tryon’s famous rat-maze experiment demonstrated that the difference between rat performances was genetic since their environments were controlled and identical.