Bimodal Information Processing in Sonar Performance

Two experiments were conducted to determine whether sonar targets could be more quickly and easily detected and recognized when auditory and visual information was provided simultaneously rather than separately. In the first experiment, 20 men were presented target stimuli embedded in noise in either the visual or auditory modality or in both at once. Response thresholds to visual and auditory stimuli were lowest when functionally redundant targets were presented simultaneously in both modalities, indicating facilitation in performance over either unimodal condition. In the second experiment, 28 men made choice reaction time (RT) responses based on their ability to recognize different sonar targets presented in varying unimodal and bimodal conditions. RT in the bimodal condition, when the same target was presented in each modality, was as fast as the faster single modality (auditory) and more accurate than either unimodal condition. The combined results provide evidence that the use of two modalities is as good or better than one for detecting, recognizing, and quickly reacting to sonar-like targets, when the information in each modality is functionally the same.