Saliency affects the width of the audiovisual integration window

Previous studies on multimodal integration have shown that a co-occurring stimulus within an unattended modality (e.g. sound) can improve behavioural performance of the attended one (e.g. vision; Bolognini, 2003; Stein, 1996). Here, we investigate the influence of visual contrast and stimulus onset asynchronies (SOAs) on this effect. Visual stimuli (gabor gratings) of different contrast levels were presented with or without sound stimuli, while subjects performed a visual detection task. The stimulus onset asynchrony of visual and auditory stimuli was also manipulated (9 SOAs, range: 200 ms visual leading to 200 ms auditory leading, steps: 50ms). For low-contrast stimuli, we found that d-prime was significantly enhanced only for synchronous audiovisual condition (SOA 0 ms) relative to the unimodal visual condition; for higher contrast stimul