The influence of the cross-modal emotional pre-preparation effect on audiovisual integration

Previous studies have shown that the cross-modal pre-preparation effect is an important factor for audiovisual integration. However, the facilitating influence of the pre-preparation effect on the integration of emotional cues remains unclear. Therefore, this study examined the emotional pre-preparation effect during the multistage process of audiovisual integration. Event-related potentials (ERPs) were recorded while participants performed a synchronous or asynchronous integration task with fearful or neutral stimuli. The results indicated that, compared with the sum of the unisensory presentation of visual (V) and auditory (A) stimuli (A+V), only fearful audiovisual stimuli induced a decreased N1 and an enhanced P2; this was not found for the neutral stimuli. Moreover, the fearful stimuli triggered a larger P2 than the neutral stimuli in the audiovisual condition, but not in the sum of the combined (A+V) waveforms. Our findings imply that, in the early perceptual processing stage and perceptual fine processing stage, fear improves the processing efficiency of the emotional audiovisual integration. In the last cognitively assessing stage, the fearful audiovisual induced a larger late positive component (LPC) than the neutral audiovisual. Moreover, the asynchronous-audiovisual induced a greater LPC than the synchronous-audiovisual during the 400–550 ms period. The different integration effects between the fearful and neutral stimuli may reflect the existence of distinct mechanisms of the pre-preparation in terms of the emotional dimension. In light of these results, we present a cross-modal emotional pre-preparation effect involving a three-phase emotional audiovisual integration.