Obtained reaction time (RT) distributions from 2 practiced Ss (aged 21 and 35 yrs) in a go/no-go detection task with attention divided across the visual and auditory modalities. Redundant signals were sometimes presented asynchronously on the 2 modalities, with the time between signals varying from 0 to 167 msec. An extension of the inequality derived by J. O. Miller (see PA, Vol 68:248) was used to test between separate-decisions models, in which the response is initiated solely by whichever signal is detected first, and coactivation models, in which both signals contribute to the activation of a single response. As in previous studies with bimodal detection tasks, the results contradict separate-decisions models and favor coactivation models.