EDA was measured from the fingertips as participants viewed scenes from a closed-captioned movie while loud tones were intermittently delivered. Four measures of EDA were derived. Skin conductance level was a measure of the participants’ tonic resting level measured at the end of the session. Skin conductance response frequency is a count of the number of tones to which the participant responded. Skin conductance response amplitude is the mean magnitude for trials that participants had an observable response. EDA factor score is a global measure using a factor score derived from a model fit to the three skin conductance measures. Electrodermal hyporesponsiveness is characteristic of schizophrenia (Bernstein et al. 1982), and deviations in skin conductance activity are present in the first-degree relatives of schizophrenia patients (Iacono et al. 1999).
