Effects of chlorprothixene, haloperidol, and trifluoperazine on the delayed-matching-to-sample performance of pigeons.

The effects of chlorprothixene (4,6,8, and 10 mg/kg), haloperidol (0.13, 0.25, 0.38, and 0.5 mg/kg), and trifluoperazine (0.5, 1,2, and 3 mg/kg) were examined in pigeons responding under a delayed-matching-to-sample procedure in which delays of 0.5-, 1-, 2-, 4-, and 8-sec duration were arranged during each experimental session. Both chlorprothixene and trifluoperazine typically reduced accuracy (percent correct responses); the magnitude of this effect was generally largest at the longest delay values. Chlorprothixene was associated with an increased rate of responding to the sample stimulus in two of three subjects, whereas trifluoperazine almost always decreased response rate. Haloperidol at high doses decreased response rate, but failed to consistently impair accuracy at any dose or delay value.