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SLOW BRAIN POTENTIAL MANIFESTATIONS OF THE ORIENTING REFLEX: EFFECTS OF INTENSITY, PROBABILITY, DEGREE AND DIRECTION OF CHANGE
Abstract
Slow wave components of the event-related brain potential (ERP) were investigated as possible indicators of the brief, transient period of involuntary attention known as the orienting reflex (OR). Convergent information was also derived from concomitant heart rate (HR) changes. Subjects were asked to count 10 series of 200 ms, 1000 Hz tone pips at 20, 40, or 60 dB SL. In some series the intensity was held constant and in other series the intensity varied unpredictably. Responses were studied as functions of stimulus intensity, probability, degree and direction of intensity change between different stimuli within a series. Since a within-subjects design was used and responses were averaged over trials, it was not possible to assess for habituation effects. However, the averaged HR responses consistently showed a brief initial deceleration that has traditionally been interpreted as an indicator of the OR. HR deceleration was greater for an intensity increase than a decrease, but was not significantly related to the degree of change. The ERP responses over the various conditions showed a consistent structure, including P300 and early and late O wave components. P300 amplitude was significantly responsive to the effects of stimulus intensity. P300 amplitude was also greater for an intensity increase than a decrease, but was not reliably related to the degree of intensity change. However, P300 did reflect stimulus processing, in that significantly larger P300 amplitudes were elicited by rare than by frequent stimuli. O wave amplitudes were consistent with Sokolov's (1963) stimulus comparator theory of OR elicitation. The O waves were elicited by decreases as well as increases in stimulus intensity in proportion to the degree of intensity change. These results are discussed in terms of their implications for the existence of a neuronal model consisting of expected stimulations. An interpretation of the O waves as reflecting the detection of stimulus change is proposed.
Subject Area
Psychobiology
Recommended Citation
PAIGE, STEPHEN R, "SLOW BRAIN POTENTIAL MANIFESTATIONS OF THE ORIENTING REFLEX: EFFECTS OF INTENSITY, PROBABILITY, DEGREE AND DIRECTION OF CHANGE" (1985). ETD collection for University of Nebraska-Lincoln. AAI8516879.
https://digitalcommons.unl.edu/dissertations/AAI8516879