Age-related differences in rats’ spontaneous alternation

Fifteen-day-old rats made random choices in a T-maze, while adult levels of alternation (approximately 70%) were noted among 30-day-olds. Also, younger pups were insensitive to a lengthening of the intertrial interval, unlike older animals whose rate of alternation decreased when a 1-h delay was interposed between arm entries. These findings are consistent with the hypothesis that hippocampal development is a factor in the ontogeny of postweaning locomotion. The unsystematic pattern of goal-arm selections among 15-day-olds suggests that ontongenetic variation in the utilization of stimuli may underlie developmental shifts in spontaneous alternation.