Behavioural antagonism between chlorpromazine and noise in man

The effects of 25 mg and 75 mg of chlorpromazine and of 95 dBA of white noise were studied separately and together in 12 male human subjects. Performance, analysed by signal detection theory, showed that both noise and chlorpromazine applied separately caused impairment in similar ways. Suspended judgements were reduced and negative decisions correspondingly increased at low levels of evidence. When applied together, chlorpromazine and noise cancelled out each other's adverse effects. It is concluded that chlorpromazine is a specific behavioural antagonist of the stressful effects of noise.