Human sensory dominance

Abstract

Human Ss matched an auditory and a visual stimulus for subjective magnitude. Then each stimulus was used as a cue in a reaction time task. On occasions when both stimuli were presented simultaneously, Ss' responding was seen to be dominated by the visual stimulus. Of further interest was the finding that on some occasions of simultaneous light-tone presentation Ss were unaware that the tone had been presented. This apparent prepotency of the visual over the auditory stimulus was seen to persist across a variety of experimental conditions, which included giving Ss verbal instructions to respond to the tone when both stimuli were presented simultaneously.Organisms are constantly exposed to a contiguous array of stimuli rather than to the isolated action of a single stimulus. Of this array, certain stimuli are more likely to be attended to than others. Such stimuli may be called prepotent for that particular organism. It has been shown, for example, that cats will attend only to the auditory component of a compound CS made up of a soft low tone and a bright flashing light. Thus, sound stimuli appear to be prepotent over light stimuli for the cat (Jane, Masterton, & Diamond, 1965).The four experiments described below represent a comparison ofthe auditory and visual modalities as to sensory prepotency for one of the most frequently used Ss in psychological research, the college freshman. EXPERIMENT IExperiment I involved observing the behavior that occurred when Ss were simultaneously presented with an auditory and a visual stimulus of equal subjective intensity, each of which had a characteristic response associated with it. MethodTen freshman psychology students at the University of Pittsburgh served as Ss. The group was composed of six males and four females. In a dimly illuminated room, each S was seated 4S em in front of a 30-cm-sq stimulus panel containing a S-cm speaker and a 6-W incandescent light source. Each S first matched an auditory and a visual stimulus for subjective intensity by adjusting the light with a Powerstat variable autotransformer until it was as bright as a . 4,OOO-Hz, 6S-dB SPL tone was loud. Then the matched stimuli were used as cues in a reaction time (RT) task.Each S placed his index fingers over two telegraph keys located directly in front of him. One key was designated as the "tone key," while the other was called the "light key." The right key was the tone key for five Ss, and the left key was the tone key for the remaining five Ss. There was one left-handed S in each condition. *This research was supported by U.S. Public Service Grant NS09027-03 from the National Institute of Neurological Diseases and Stroke. The author is indebted to Ross Perilman, who ran the Ss in Experiment II.S was instructed to press the tone key as soon as he heard the tone, or the light key as soon as he saw the light. A keypress terminated the stimulus. Light and tone onsets were manually controlled by E. A Standard timer measured RTs in milliseconds. After four practice trials, each S was given 30 simple RT...

A deafening flash! Visual interference of auditory signal detection

“…In particular, a bias towards processing stimuli in the visual modality might have benefitted visual sequence discrimination relative to auditory, while causing visual stimuli to distract more from auditory signal detection. However, our measure of the Colavita effect (Colavita, 1974;Koppen et al, 2009) helps to discount this possibility. Though we successfully replicated the Colavita effect, this did not predict performance in either task, thus there is no evidence that the present results can be accounted for by general differences in bias towards the visual modality.…”

“…In a later session we administered the test of sensory dominance (Colavita, 1974) to 24 of our original participants who were still available. We presented participants with 10 blocks of 100 randomised trials, where 20% of trials were bimodal and the remaining 80% were divided equally between unimodal visual and auditory trials.…”

“…The order of these two tasks was counterbalanced between subjects. We also included a measure of visual dominance over audition (Colavita, 1974;Koppen et al, 2009), with three randomly interleaved conditions: auditory only, visual only and audiovisual; the dependent measure was the accuracy for identifying the modality of the stimulus.…”

“…To assess this, we subsequently obtained a measure of visual dominance over audition following Colavita (1974) …”

“…We predicted that participants who benefitted from auditory-recoding of visual stimuli in the sequence discrimination task might be affected more by irrelevant flashes in the auditory signal detection task, because they would be experiencing concurrent visually-evoked auditory sensations. We also measured and controlled for individual biases in the dominance of the auditory modality relative to visual (Colavita, 1974;Koppen, Levitan, & Spence, 2009), in case this influenced our other objective measures.…”