Passive avoidance in prenatally X‐irradiated rats

Abstract Twenty‐nine albino rats which had received 200 R of X irradiation on the 16th day of gestation were given together with 38 nonirradiated control animals, 4 trials in a passive avoidance conditioning situation. Irradiated animals showed significantly more passive avoidance behavior than did the controls. In a second experiment, animals from both groups were subsequently tested in a shuttle‐box, active avoidance situation. Here, also, the irradiated animals showed more avoidance behavior than the controls. It was hypothesized that the findings are related to increased fearfulness in prenatally irradiated rats.