Age factors in sex differences in open-field activity of rats

Abstract

Male and female Long-Evans rats were given open-field tests at 30 and/or 120 days of age. At 30 days of age, males and females did not differ in their open-field behavior. At 120 days of age, however, females locomoted more, reared more, and showed less wall-hugging than males, regardless of whether or not the animals had received tests in the open field at 30 days of age. The appearance of sex differences was due to an increase in the scores of the females between 30 and 120 days of age. © 1976 Psychonomic Society, Inc.