Audiovisual speech integration development at varying levels of perceptual processing

Abstract

There are multiple mechanisms of audiovisual (AV) speech integration with independent maturational time courses. This study investigated development of both basic perceptual and speech-specific mechanisms of AV speech integration by examining AV speech integration development across three levels of perceptual processing. Twenty-two adults and 24 6- to 8-year-old children completed three auditory-only and AV yes/no tasks varying only in the level of perceptual processing required to complete them: detection, discrimination, and recognition. Both groups demonstrated benefits from matched AV speech and interference from mismatched AV speech relative to auditory-only conditions. Adults, but not children, demonstrated greater integration effects at higher levels of perceptual processing (i.e., recognition). Adults seem to rely on both general perceptual mechanisms of speech integration that apply to all levels of perceptual processing and speech-specific mechanisms of integration that apply when making phonetic decisions and/or accessing the lexicon; 6- to 8-year-old children seem to rely only on general perceptual mechanisms of AV speech integration. The general perceptual mechanism allows children to attain the same degree of AV benefit to detection and discrimination as adults, but the lack of a speech-specific mechanism in children might explain why they attain less AV recognition benefit than adults.