Loudness judgments, evoked potentials, and reaction time to acoustic stimuli early and late in the cardiac cycle in chronic schizophrenics.

Two experiments were performed to test Broen's (1968) theory that chronic schizophrenics show increased sensitivity of the inhibitory mechanisms assumed to follow cardiovascular baroreceptor stimulation. Subjects were chronic schizophrenics and normals matched for age and education. In Experiment I reaction times, vertex potentials, and loudness judgments to single tones presented during systole or diastole were analyzed. Contrary to expectation, schizophrenics more often judged tones presented during systole to be louder than tones presented during diastole; the opposite was true for normals. A similar pattern was found in Experiment II, where pairs of tones were presented instead of single tones. No influence of cardiac cycle on reacion time or evoked potentials emerged. Results do not support Broen's assumption.