| Résumé |
Recognizing a natural object requires one to pool information from various sensory modalities, and to ignore information from competing objects. Realistic objects are of interest in the study of auditory-visual integration, since a given object can generally be identified through any of several single sensory modalities. Here we studied the influence of semantic congruence (i.e. if the auditory and the visual stimulation come from the same object or not) and semantic interference (i.e. the influence of a distractor in one modality on the recognition in the other modality) on auditory-visual object recognition, in a go/no-go task. Participants were asked to react as fast as possible to a target object presented in the visual and/or the auditory modality, and to inhibit their response to a distractor object. The experiment was run under an immersive and realistic virtual environment including 3D images and free-field audio. Reaction times were significantly shorter for semantically congruent bimodal stimuli than predicted by independent processing of information about the objects presented unimodally (see Miller, 1982). Interestingly, this effect was twice as large as found in previous studies that used information-rich stimuli (e.g. Giard & Peronnet, 1999; Molholm et al., 2004; Laurienti et al., 2004). The processing of bimodal objects was also influenced by their semantic congruence: reaction times were significantly shorter for semantically congruent bimodal stimuli (i.e., visual and auditory stimuli from the same object target) than for semantically incongruent bimodal stimuli (i.e. target represented in only one sensory modality and distractor presented in the other modality). Importantly, an interference effect was observed (i.e. longer reaction times to semantically incongruent stimuli than to the corresponding unimodal stimulus) only when the distractor was auditory. When the distractor was visual, the semantic incongruence did not impair recognition. Our results show that immersive displays may produce large multimodal integration effects. They also reveal a possible asymmetry in the attentional filtering of irrelevant auditory or visual information. |
