A sensitive period for the maintenance of emotionality in Mongolian gerbils

Gerbils reared and continuously housed in cages providing access to shelter respond throughout life to sudden visual stimulation by fleeing, hiding, and foot thumping. In the present 5 experiments with a total of 788 gerbils, Ss reared and housed in cages lacking shelter exhibited this pattern of response to stimulation at 26 and 31 days of age but not at greater ages. During a limited period (Days 30–60 after birth) experience with shelter was sufficient to maintain reactivity to stimulation, but similar experience with shelter at 21, 90, or 126 days of age was not sufficient to do so. These findings indicate (a) that shelter experience is a necessary condition for the maintenance of enhanced reactivity to stimulation but not for its development and (b) that gerbils are not equally sensitive to shelter experience throughout life. (17 ref)