Interaction of the Auditory and Visual Sensory Modalities

The general observation that dual sensory input enhances signal detectability is of considerable interest from the information-processing standpoint. Previous experiments on the effects of intersensory interaction have been concerned primarily with an observer's performance on a vigilance task. These studies have not produced results that are sufficiently precise to define the extent and manner of sensory interaction. This study is concerned with obtaining precise measurements of interaction occurring between auditory and visual sensory-information-processing networks. Separate auditory and visual threshold functions are determined and analyzed in terms of signal-detection theory. A bisensory threshold function is also determined, using equated stimuli levels derived from the individual sensory functions. The results of the bisensory test are compared to a theoretically derived curve based on the hypothesis of probabilistic adding and are found to have good correspondence.