Standardization Within Individuals: A Simple Method to Neutralize Individual Differences in Skin Conductance

The present paper suggests a method to neutralize individual differences in skin conductance responsivity. The method suggested is a standardization of the responses within individuals. This method was compared to the range correction transformation suggested previously. The comparison was based on data from two experiments which evaluated differences between electrodermal responses to relevant and neutral stimuli in information detection tasks. In the first experiment the range correction transformation used the maximal skin conductance response evoked by the subject to one of the regular stimuli presented in the information detection task. The second experiment included responses to unpleasant tones and the range correction transformation was defined as the skin conductance response evoked by the subject to a given stimulus, divided by the response to the unpleasant stimulus. A bootstrap analysis was carried out on five data sets gathered from the two experiments, to statistically compare the transformations. In all cases standard scores better discriminated relevant and neutral stimuli, than range corrected scores. The advantage of standardization was much more salient in the second experiment, where only standard scores produced a statistically significant difference between strong and weak experimental conditions. The analysis demonstrated that the advantage of the method of standard scores is related mainly to its reliance upon the mean, which is a more stable and reliable statistic than the maximal response.