Introduction

Perception has traditionally been viewed as a modular function, with the different sensory modalities operating largely as separate and independent modules. To the degree that this thesis holds, it has contributed to progress in both empirical and theoretical research on the perceptual brain, yet to the degree that it has been overemphasized, it has masked the need for intensive research on cross-modal interactions. Perhaps for this reason multisensory integration has been one of the least studied areas of research in perception. As a result, prior to the very recent surge of interest in this topic, knowledge about multisensory integration and cross-modal interactions remained largely at the level of phenomenology. Even at this level, however, many important questions remain unanswered. Because vision has traditionally been viewed as the dominant modality (Howard & Templeton, 1966; Welch & Warren, 1986), most studies have focused on the effects of visual stimulation on perception in other modalities, and consequently the effects of other modalities on vision are not as well understood.