This study examined effects of arousal level on the physiological responses in a polygraph examination using the Concealed Information Test (CIT). Thirty-nine healthy college students were tested with or without evaluative observation. Electrodermal activity, blood pressure, heart rate, normalized pulse volume, and respiration were recorded. Observation elevated participants' arousal level, which was manifested in self-reports, high skin conductance level, and low normalized pulse volume (i.e., vasoconstriction). However, differential reactivity to critical and non-critical items on the physiological measures was less affected by observation. These results suggested that participants' arousal level has little effect on differential physiological reactivity on the CIT.
