| Popis: |
Psychophysiologists often record electrodermal activity (EDA) exosomatically to derive measures of slow, tonic activity—skin conductance level (SCL)—and faster, more punctate changes—skin conductance responses (SCRs). An SCR is considered relevant when its amplitude exceeds a researcher-determined threshold (e.g., 0.05 μS), typically fixed across study participants and conditions. However, fixed SCR thresholds may detect more SCRs in samples with higher SCL because the number and amplitude of SCRs correlate positively with SCL. To address this issue, we developed a novel fixed plus adaptive (FA) thresholding method that adjusts SCR detection as a function of the prevailing SCL. We hypothesized greater statistical power to detect a difference in the rate of SCRs across high vs. low arousal stimuli using FA thresholding compared to fixed thresholding. Study 1 consisted of 254 young adults measured in a laboratory using wired EDA sensors during exposure to evocative images and sounds. Study 1 constituted our exploratory dataset, wherein we found an optimal FA threshold of 1.9% that maximized the ability to detect a difference in SCR rate between high vs. low arousal stimuli. Study 2 involved 20 children with autism repeatedly measured in a clinic using wireless EDA sensors during several behavioral tasks. Study 2 constituted our validation dataset, wherein FA thresholding at 1.9% increased statistical power to detect a difference in SCR rate between high vs. low arousal tasks, compared to fixed thresholding at 0.05 μS. Future research should test for reproducibility and generalizability of our results in other tasks, samples, and contexts. |
