The Sa were seated in a comfortable chair facing a hidden speaker. The finger cup was sealed to the tip of the right finger with a caulking compound (Nu-Calk) and the hand was allowed to rest on the wide arm of the chair. The other recording equipment was attached and Ss were left alone in the BOund-controlled testing room. The Ss were randomly assigned to short-and long-stimulus groups (20 introductory psychology students in each group). During the habituation sequence the stimulus duration

more »

... 2 sec. for the short-stimulus group and 20 sec. for the longstimulus group. The stimuli were presented repeatedly until Ss reached a habituation criterion, defined by the GSR measure 88 three successive METHOD The apparatus and procedure, with the exception of those directly related to the vasoconstriction measure, are more fully described in. the report of the GSR results (Koepke & Pribram, 1986). Apparatus Variation In vWlOconstriction was monitored continuously with a digital plethysmograph. The tip of the index finger was sealed in a small plastic cup approximately 2 X 4 cm., which was connected by a plastic air tube to a Decker Pressure Sensor (No. 300) and a Decker Unit 902. The output of these units was reflected on a Brush recorder, Mark II run at the speed of 1 mm/sec. The stimulus was a pure tone of 1,000 cps with an intensity of 94-db. SPL. The duration of the tone was either 2 or 20 sec.