[Skin conduction as an indicator of cognitive and emotional processes]

Classical conditioning experiments can be used to study both cognition and emotions. In studies involving human subjects two different scores based on the human skin conductance response are generally used: the "first interval responses" (FIR) and the "second interval responses" (SIR). The SIR is thought to reflect cognitive but not emotional processes, while the FIR is assumed to reflect both. An experiment with two groups of subjects (n = 20 each) was run in order to demonstrate that the SIR indeed is able to reflect emotional processes. Each group was trained with five different conditioned stimuli, each of which was paired with a specific unconditioned stimulus. These unconditioned stimuli varied in aversiveness. Immediately after training, skin conductance responses to combinations of already trained conditioned stimuli were examined. The sequence of testing was varied across groups. Our results clearly showed that the SIR reflected aversiveness, while the FIR was confounded by orienting responses under these experimental conditions.