Laboratory studies have shown that concealed-information recognition is associated with heart-rate deceleration, which is indicative of "orienting," which occurs when arousal is low and threat is distant. When arousal increases, orienting may switch to defensive responding. Previous laboratory setups did not allow for the examination of this possibility, since they failed to induce the stress level similar to that observed during real-life criminal interrogations. In the current study, baseline heart rate (92 bpm) was similar to that reported in real-life criminal interrogations, indicating that the polygraph examination was stress inducing. Despite this increased stress level, participants reacted with greater heart-rate deceleration in responding to the correct items compared to the control items, which is indicative of enhanced orienting. These data indicate that orienting accounts for the physiological changes stimulated by concealed information. Data from all comparison-question tests conducted by the Belgian Federal Police between December 1, 2007, and April 3, 2008, were considered eligible for the current study (n=87); however, the final sample consisted of 65 participants, including 3 women. They were suspects in severe crimes. The tests followed the steps that are common for comparison-question tests. Data were analyzed with psychophysiological analysis, an interactive software program the authors developed for the off-line analysis of psychophysiological data. 1 table, 1 figure, and 35 references