Combining evidence presented simultaneously to the eye and the ear: A comparison of some predictive models

Data from a sustained monitoring experiment involving auditory, visual and combined audio-visual signal recognition were used to assess the predictive validity of five models of bisensory information processing. Satisfactory predictions of the dual-mode performance levels were made only by two models, neither of which assumes that the auditory and visual systems operate independently, and correlations which attest to this nonindependence are presented. One of these models explicitly assumes that the two systems are associated so that their judgments tend to coincide; the other assumes that the visual system “alerts” the auditory system to the presence of a signal. Both models accurately predict the levels of d’ and β in the dual-mode condition, and the “alerting” one also accounts for the observed reduction in response latencies.