A psychophysiological inquiry into the nature of the Sokolovian orienting response comparator model: skin conductance and EEG data.
The mechanisms which trigger the orienting response (OR) are still the subject of lively debate. Sokolov (1990) proposes the development of a multidimensional model of the physical parameters of stimulation. Recent OR research has shown that the skin conductance OR (SCOR) is related to task demands and controlled processing, although this is not so clear for central physiological indexes of orienting. Seventy-three subjects performed visual discriminations of stimuli within a warning-stimulus paradigm. The physical complexity of stimuli and their task relevance were manipulated within subjects, while the nonspecific effects of workload were controlled with a group factor. SCORs were measured concurrently with 1-s epochs of EEG alpha and theta power from Fz, Cz, Pz, and Oz. Neither index was reliably affected by the physical complexity of stimulation alone. However, both higher task relevance and higher workload significantly increased the magnitude of EEGORs and SCORs. Task averages of central and autonomic activity showed an overall pattern of covariation, but a second-by-second breakdown of EEG spectra suggests that the SCOR may be an aggregate of the activation of diverse brain mechanisms responsible for physiological orienting. The results are consistent with a model of orienting as a continuous dimension of resource allocation to anticipated and current task demands, rather than with the abrupt dichotomy between voluntary and involuntary orienting. Implications for the classical OR Sokolovian model are discussed.
Department of Psychology, University of Southampton, UK.
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Barceló
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Hall
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Gale
D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D004569:Electroencephalography; D004585:Electrooculography; D005712:Galvanic Skin Response / Q000502:physiology*; D006801:Humans; D009949:Orientation / Q000502:physiology*; D013647:Task Performance and Analysis