The effects of some phenothiazine derivatives on the discrimination of auditory clicks

Summary

This study describes the effects of chlorpromazine, promethazine, perphenazine and trifluoperazine at each of four dose levels on the discrimination of the frequency rate or at several different standard auditory pulse rates.

Thirty subjects recruited from local colleges participated in the study. Four groups of five subjects each were administered one of the four drugs at each of four dose levels. Discrimination was assessed by use of the three-category Method of Constant Stimuli after each dose of the drug and after the administration of placebo. A control group of ten subjects were subjected to the same discrimination procedures without the administration of drug or placebo.

The results suggest that one of the aliphatic derivatives, chlorpromazine, impaired discrimination (as assessed by both the difference limen and standard deviation of judgments) at both high and low standard frequencies. The other aliphatic derivative, promethazine, impaired discrimination only at the higher frequency. Increases in the difference limen under the higher doses of chlorpromazine was related to a systematic increase in the use of equal judgments at these dose levels.

The piperazine derivatives, perphenazine and trifluoperazine, were not observed to impair discrimination as measured by either the difference limen or the standard deviation of judgments. However, a “crescent” shaped dose curve for the difference limen was noted under perphenazine which was consistent with similar dose effects which have appeared when other, different, behavioral measures were used.