Signal reliability modulates auditory-tactile integration for event counting.

Sequences of auditory beeps and tactile taps were simultaneously presented and participants were instructed to focus on one of these modalities and to ignore the other. We tested whether (i) the two sensory channels bias one another and (ii) the interaction depends on the relative reliability of the channels. Audition biased tactile perception and touch biased auditory perception. Lowering the reliability of the auditory channel (i.e. the intensity of the beeps) decreased the effect of audition on touch and increased the effect of touch on audition. These results show that simultaneous auditory and tactile stimuli tend to be automatically integrated in a reliability-dependent manner.