Intensity and Task Effects on Evoked Physiological Responses to Noise Bursts

Authors

  • Walton T. Roth,

    Corresponding author
    1. Laboratory of Clinical Psychopharmacology and Psychophysiology, VA Medical Center, Palo Alto, California, and Department of Psychiatry and Behavioral Science, Stanford University School of Medicine
      Address requests for reprints to: Walton T. Roth, M.D., Psychiatry (116A3), V.A. Medical Center, 3801 Miranda Ave., Palo Alto, California 94304, U.S.A.
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  • Karen H. Dorato,

    1. Laboratory of Clinical Psychopharmacology and Psychophysiology, VA Medical Center, Palo Alto, California, and Department of Psychiatry and Behavioral Science, Stanford University School of Medicine
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  • Bert S. Kopell

    1. Laboratory of Clinical Psychopharmacology and Psychophysiology, VA Medical Center, Palo Alto, California, and Department of Psychiatry and Behavioral Science, Stanford University School of Medicine
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  • A version of this paper was presented as part of a Science Fair at the Twenty-Second Annual Meeting of the Society for Psychophysiological Research in Minneapolis, Minnesota, October 1982.

  • Preparation was supported by the Medical Research Service of the Veterans Administration, NIMH Special Research Center grant MH 30854, and NIMH grant MH 35330. We thank Maya L. Kopell, Margaret J. Rosenbloom, and Adolf Pfefferbaum for their assistance, and Lois E. Putnam for her advice about methods of heart rate analysis. We are grateful to Risto Näätänen, Alvin S. Bernstein, and Walter Ritter for comments on an earlier draft of this paper.

Address requests for reprints to: Walton T. Roth, M.D., Psychiatry (116A3), V.A. Medical Center, 3801 Miranda Ave., Palo Alto, California 94304, U.S.A.

ABSTRACT

To compare the sensitivity of a variety of psychophysiological variables to stimulus intensity and attention parameters, we simultaneously recorded EEG, eyeblink, skin conductance, and heart rate responses. Twelve subjects were presented with 50-ms, abrupt onset, white noise bursts of four intensities: 65, 80, 95 and 110 dB SPL. Nineteen stimuli of each intensity were given in random order with ISIs between 12 and 17 seconds. This paradigm was repeated under three randomly ordered task conditions: simple reaction time to the noise bursts, passive sitting, and visual tracking.

Response components were evaluated by Principal Components Analysis and peak measurement. Several factors and peaks increased with intensity, including those representing P300 and the Slow Wave. Task also had marked effects on certain components. SCR amplitude decreased rapidly over time, while the amplitudes of P300 and other event-related potentials did not.

The findings do not allow the late positive event-related potential components to be classified unambiguously as orienting, defense, or startle responses. Cognitive theories of these components have little predictive power for the observed intensity effects.

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