Frequency of attack in shock-elicited aggression as a function of the performance of individual rats.

Fighting rates between paired rats were investigated as a function of the probability of attack by a single animal. Animals from stable high-fighting and low-fighting frequency pairs were intermatched to detect individual high-fighting and low-fighting rats. Pairs of high-fighting animals then received saline or different chlorpromazine dosages during successive sessions. Finally, single high-fighting members of each pair also received the different drug dosages. The chief findings were that: (a) rats showing high fighting rates when matched against each other revealed low fighting rates when matched against one, but not the other member of a low-fighting pair; and (b) high-fighting rats decreased their fighting rates as their own or their opponent's chlorpromazine dosage increased. These results indicated that a low rate of fighting on the part of one rat results in a low fighting rate on the part of its opponent.