Assessing the role of attention in the audiovisual integration of speech

Currently, one of the most controversial topics in the study of multisensory integration in humans (and in its implementation in the development of new technologies for human communication systems) concerns the question of whether or not attention is needed during (or can modulate) the integration of sensory signals that are presented in different sensory modalities. Here, we review the evidence on this question, focusing specifically on the integration of auditory and visual information during the perception of speech. Contrary to the mainstream view that has been prevalent for the last 30 years or so, recent studies have now started to reveal that attentional resources are, in fact, recruited during audiovisual multisensory integration, at least under certain conditions. Finally, considering all of the available evidence, we discuss the extent to which audiovisual speech perception should be considered to represent a ‘special’ case of audiovisual, and more generally, of multisensory integration.