Use of operant response duration to distinguish the effects of haloperidol from nonreward.

Prior experimentation, making exclusive use of operant response rate, has offered conflicting evidence regarding the role of reinforcement and motor effects in neuroleptic-induced changes in operant responding. In the present work, response rate and response duration were recorded for 12 rats responding under a fixed-ratio 10 schedule of food reinforcement. On six consecutive days separate groups of animals were given haloperidol or saline-with-extinction. Although both drug treatment and extinction produced elevated durations compared to pre-treatment baseline, the haloperidol group exhibited response durations that were significantly higher than those of the no-drug-extinction group. In view of these results, and since prior work has shown that response duration provides information which is nonredundant with response rate, it is suggested that response duration may be a valuable tool in future work attempting to partial out the motivational and motor effects of neuroleptics on operant responding.