Psychological Stress Evaluator—Two Tests of a Vocal Measure

The Psychological Stress Evaluator (PSE), a commercial lie detector employing voice analysis, was tested on two laboratory tasks. On the guilty knowledge task of Lykken (1960), 20 subjects were interrogated on personal information after being offered a reward to fool the interrogator. PSE analysis failed to identify correct responses beyond chance levels. On the mental arithmetic task of Kahneman, Tursky, Shapiro, and Crider (1969) and Tursky, Schwartz, and Crider (1970), 16 subjects performed arithmetic problems which varied in difficulty but were performed under identical pacing. According to PSE scoring, stress increased with task difficulty. In addition, the PSE‐measured differences occurred with high consistency across subjects. Some aspects of PSE analysis may be valid for the measurement of stress, although the validity of the analysis for practical lie detection is questionable.