[Effect of self-relevance of a non-critical item on physiological responding on the Concealed Information Test]

The effect of self-relevance of a non-critical item in the Concealed Information Test (CIT) was investigated. Respiration, skin conductance response (SCR), heart rate, and normalized pulse volume were recorded while performing the CIT using a stimulus set composed of 4 items (with one self-relevant item). Thirty participants were instructed to recognize one item as critical and the remaining items as non-critical (positive group), and 33 participants were instructed to recognize all items as non-critical (negative group). In the positive group, a differential reactivity was observed between the critical and non-critical items, despite the self-relevance of the non-critical item. In the negative group, a differential reactivity between the self-relevant and non-self-relevant items was observed for SCR only. However, when individual data were analyzed, there was a differential reactivity between self-relevant and non-self-relevant items on physiological measures other than SCR for some participants in the negative group. These results suggest that the self-relevance of a non-critical item might cause false positive results in "negative" participants, particularly when only SCR is used to assess differential reactivity.