Interactive effects of unpleasant light and unpleasant sound

Abstract

IN tests of colour preference, rhesus monkeys have been found to have a strong aversion to light at the red end of the spectrum^1,2. No comparable reaction to colours has been described in healthy human beings although in patients who are suffering from cerebellar or spinal disorders colours may assume a new potency. Thus it has been claimed that in cerebellar patients who exhibit the so-called ‘sensori-motor induction syndrome’, red light not only exacerbates the motor disorder but disrupts thought processes and leads to acute subjective distress, whereas blue-green light alleviates the symptoms^3,4. Furthermore, Halpern and Feinmesser⁵ found that in such patients red light, besides causing discomfort in itself, increases the sensitivity to noxious auditory stimulation: in their experiments the ‘threshold of acoustic discomfort’ was consistently lowered when the patients wore red filters in front of their eyes. So we have investigated in monkeys whether the aversion to red light is increased when the preference tests are conducted in the presence of unpleasant background noise.