Effects of chlorpromazine on exploration and habituation in the rat.

1. The effects of chlorpromazine, 2 and 4 mg/kg, on exploration were investigated under two independent influences-food deprivation and time of day.2. Rats had three 3-minute trials in a hole-board apparatus; hole-investigation (head-dips) and general motor activity were recorded.3. On trial 1 chlorpromazine reduced exploration to half the control level, but on trial 3 it had no effect on motor activity or head-dips.4. General activity habituated from trial 1 to 3 in all groups, but some of the drug groups did not show significant habituation of head-dips, due to the low level of responding on trial 1.