Multimodal signal detection: Independent decisions vs. integration

The pooling of information from simultaneous, spatially congruent auditory and visual stimuli is examined in a signal detection task. The paradigm used permits discrimination among a number of models of the decision mechanisms involved in processing multiple component stimuli. Parameter-free predictions are presented for the weighted integration model and for three versions of the independent decisions model. The data support an independent decisions model of the bimodal detection process in which attention is shared equally between modalities.