Hemispheric asymmetries for the temporal resolution of brief auditory stimuli

Abstract

This study investigates a left-hemisphere (LH) advantage for the discrimination of fine temporal events within the auditory modality in 24 normal adults. Brief noise bursts were delivered monaurally to the left or right ears, half of which contained a gap lasting between 2 and 8 msec. Subjects were required to indicate whether or not the noise burst contained a gap. Research within this area has yielded conflicting results. It is possible that variations in gap position or the properties of the noise burst may have contributed to this conflict. The effect of gap position was investigated by systematically varying the position of the gap during half of the trials. White noise bursts were used to avoid the use of spectral cues. Reaction time, response bias, and response error measures revealed a right-ear (and hence LH) advantage for gap detection. Stable gap positions were recognized more accurately than variable gap positions. Gap position had no effect on the observed LHadvantage. These results suggest that the auditory properties of noise burst, rather than gap position, play an important role in the discrepancies observed in this area.Research into cerebral asymmetry has suggested that the left hemisphere (LH) and the right hemisphere (RH) of the brain have different capacities for the resolution of sensory information separated by fine moments of time. Some ofthe earliest research within this field was carried out by Efron (1963aEfron ( , 1963b). Efron's experimental paradigm required neurologically normal subjects to judge whether two bilateral stimuli delivered to the left and to the right hands were simultaneous or successive. Subjects tended to judge the stimuli to be simultaneous when the stimulus to the left hand was delivered shortly before the stimulus to the right hand. Efron accounted for these results with a model of hemispheric asymmetry in which the LH was absolutely specialized for temporal processing. Performance asymmetries between the hands were believed to be the result of delays associated with the trans-callosal passage of information from the left hand. These findings have been supported by research conducted by Mills and Rollman (1980) within the auditory modality. Using a bilateral presentation procedure, they found that stimuli delivered to the left ear were perceptually delayed relative to stimuli delivered to the right ear during temporal-order judgments.Asymmetries for temporal processing have also been observed in studies which have employed unilateral presentation procedures (wherein stimuli are presented to the same side within each trial). In research conducted within the visual modality, Nicholls (1994a) has found a right-visual-field advantage for the detection of twoRobert Efron. Soren Suus, and an anonymous reviewer are thanked for their helpful comments on an earlier draft of this paper. Correspondence should be addressed to M. E. R. Nicholls, Department of Psychology, University of Melbourne, Parkville, VIC 3052, Australia (email: nicholls@psych.unimelb.edu.au). flash fus...

Crossmodal coupling of oculomotor control and spatial attention in vision and audition

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Estudo da vantagem da orelha direita em teste de detecção de gap

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Effect of lateralized gaps in noise on the cutaneous blink reflex in humans

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