Sensory Interaction: Vision is Modulated by Hearing

Abstract
An irrelevant noise was turned on at various points during a visual reaction-time task. Latencies were reliably smaller than on quiet trials, provided the noise was turned on when a subject was looking at a relevant visual stimulus. This effect occurred regardless of whether the distribution of interstimulus intervals was constant or varied during a session, as well as independently of a subject's base rate of response and level of practice in the task. But it disappeared if reaction times in completely noisy sessions were compared to performances in quiet sessions. This effect was found to vary systematically with the orientation of and the hemiretina stimulated by a test form, but not with the particular ear stimulated by a noise. A model is suggested for these and related results in which the arousal elicited by a loud sound in the central nervous system either activates associative memories of form, inhibits early components of striate cortical unit response to the intensive properties of a visual stimulus, or both.