Forty restrained rats, given tailshocks to elicit biting on a target, were given a second shock contingent on the biting at different delay times. Comparisons made in different phases among four (0, 3, 6, and 9 sec) and two (0 and 9 sec) conditions showed longer delays of punishment to produce less suppression of the biting, though not significantly so in the former comparison. The results indicated that shock stimuli in elicited aggression have dual functional properties where longer delayed and free shocks serve to elicit, while more immediately contingent shocks serve to suppress biting.