When simultaneously presented with a brief auditory and a brief visual stimulus of equal subjective magnitude, human subjects show a strong tendency to respond to the visual stimulus. The present experiments attempted to reduce or abolish this prepotency effect by manipulating the subject's visual fixation point, based upon the idea that eye orientation plays an important part in attending to either a brief auditory or a brief visual stimulus. The results suggested that visual prepotency in human subjects persists even when· peripheral rather than foveal vision is used.A recent series of experiments (Colavita, 1974) has demonstrated a strong visual prepotency in human subjects when they are placed in a conflict situation where they must respond to either a brief light stimulus or a brief tone stimulus. In these experiments, subjects matched an auditory and a visual stimulus for subjective magnitude. Then, each stimulus was used as a cue in a reaction time (RT) task_ On occasions when both stimuli were presented simultaneously, the subject's responding was seen to be dominated by the visual stimulus even when verbal instructions were given to respond to the tone in such instances. An interesting secondary finding was the fact that on some of the trials involving simultaneous lighttone presentations subjects were unaware that the tone had been presented.An attempt was made to explain the above results by referring to Broadbent's (1958) channel-switching model of information processing and attention. This model predicts that two simultaneously presented stimuli cannot be processed as effectively as the same two stimuli presented in succession. However, additional explanation is required for the fact that the visual channel is apparently sampled first by human subjects_We have proposed that for simultaneously presented auditory and visual stimuli of short duration, the resulting reflexive orienting response would more likely favor the visual rather than the auditory input. This proposal was based upon some evidence (Ades, 1944) that in the case of brief auditory and visual stimuli, the orienting response may ultimately involve the neural connections of the superior colliculus with the motor centers of the ventral tegmentum, medulla, and spinal cord. Thus, the visual channel might be sampled first by virtue of its more direct connections with the superior colliculus.Implicit in the above proposal is the idea that eye orientation plays an integral part in attending to either a brief auditory stimulus or a brief visual stimulus_ Thus, the visual prepotency noted in our RT task may be due to the fact that subjects are already fixating their gaze on the light source in anticipation of its being activated_ The two experiments reported below attempt to manipulate visual prepotency by altering subjects' visual ftxation point. EXPERIMENT IExperiment I was designed to measure sensory prepotency in a choice RT situation when the subject was instructed to use as a visual ftxation point a spot midway between the sound source an...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.