The effect of common versus distinctive stimulus features on electrodermal orientation to significant stimuli.

The relationship between electrodermal responsivity and stimulus similarity was previously demonstrated in a series of studies. These studies were guided by a feature-matching model according to which similarity is an additive function of the common and distinctive features of the stimuli. In these experiments common and distinctive features were simultaneously manipulated, thus confounding the effects of the two sets of features. In the present experiment, we examined the separate effects of these two sets of features by an independent manipulation of common and distinctive components of the stimuli. A modified version of the guilty knowledge technique was employed, with compound pictorial and verbal stimuli (schematic faces and verbal descriptions of people) as the relevant items memorized by the subjects. Skin conductance responses were measured during the subsequent presentation of a stimulus sequence comprised of a test stimulus, which shared some common components with the relevant stimulus, and several neutral control stimuli. As hypothesized, a larger number of distinctive components resulted in decreased responsivity. Yet, contrary to our expectation, the number of common components of the relevant and test stimuli had no effect on responsivity. Several hypotheses are suggested to account for this unexpected result.