Document Type


Date of Award



Learning ability, Genetic aspects, Mice, Anatomy, Testing

Degree Name

Doctor of Philosophy (PhD)



First Advisor

John L. Fuller

Second Advisor

August P. Mueller

Third Advisor

C. James Scheirer


Mice selected for high, medium, and low brain weight were raised in an enriched environment and tested on open field, active avoidance, water maze, operant discrimination, and passive avoidance tasks. Mice from one foundation stock yielded mice with high and low brain weight. The control groups for this selection were composed of one group of medium brain weight mice subjected to stabilizing selection and a heterogeneous group of mice which was not subjected to any selection. The mice in the two control groups were derived from the same foundation stock as the high and low brain weight mice. In addition, mice from the same foundation stock were independently selected for a low and an unselected control line. Another independent selection program, using a different foundation stock, yielded a high line and its unselected control. Although on each learning test statistically reliable differences in learning rate were found within each selection, there was no consistent relationship (a) within selections and across tests or (b) within tests and across selections, between increased brain weight and increased learning performance. Therefore, learning ability did not increase with increased brain weight.