In this study, we used a variation of the costs and benefits paradigm to investigate the role of endogenous and exogenous spatial attention on crossmodal interactions.
Participants had to discriminate between visual stimuli, which were presented alone or in synchrony with auditory stimuli. The duration of both the visual and auditory stimuli was manipulated giving rise to congruent or incongruent trials. Two different tasks were used: 1) Temporal discrimination: Participants discriminated the duration of the visual stimulus while ignoring the duration of the auditory stimulus, 2) Non-temporal discrimination: Participants performed a visual perceptual discrimination task where stimulus duration was irrelevant.
The results showed that the duration of the sound biased the perceived duration of the visual stimulus revealing a novel audiovisual illusion: A long sound made a short visual stimulus be perceived longer and a short sound made a long visual stimuli be perceived shorter. We also present the results of the effect of endogenous and exogenous spatial attention adding new evidence to the hypothesis that multisensory integration depends on spatial attention.