Intrasession adaptation and intersession extinction of the components of the orienting response.

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Abstract
Intrasession (adaptation) and intersession (extinction) changes in the skin resistance (SR), heart rate (HR), respiratory rate (RR), and muscle action potentials (MP) components of the orienting response (OR) to auditory stimuli of moderate intensity were compared. Adaptation and extinction curves were very similar in SR and similar in MP. There was essentially no evidence of adaptation or extinction in HR and RR or indeed systematic responsiveness. These findings support the logical inference Adaptation and extinction are equivalent processes mediated by the same neural mechanisms. Significant bilateral differences in prestimulus levels of SR did not affect responses; in each system Ss maintained their rank-order position in the group across sessions; the responses studied provided little evidence of startle components; and the generally larger reactions in SR and MP on the 1st tone each day were not related to arousal levels as measured by prestimulus levels of functioning.