INTERSENSORY DIFFERENCES IN EFFECT OF WARNING SIGNALS ON REACTION TIME

A visual signal with two equiprobable alternative values, calling for a manual choice response, was presented to the subject after a fairly long (5 sec) waiting period from the 'start' signal. The effect of introducing a warning signal at a fixed interval between 0 and 500 msec prior to the visual signal to respond was examined. When the warning signal was presented in the auditory modality, it was found that simultaneous presentation of the auditory signal improved reaction times to the visual signal and that a further improvement developed as the interval was increased to 200 msec. When the warning signal was presented visually no improvement in reaction times to the visual signal to respond was found until the interval reached 150 msec. The results from the auditory warning condition may be accounted for by the difference in conduction latencies of simultaneously presented auditory and visual signals. The results from the visual warning condition suggest that no use can be made of a warning signal entering by the same modality as the signal to respond until an interval of 100-150 msec has elapsed. © 1969.