Using response time measures to assess "guilty knowledge"

How can a suspect's guilt or innocence be reliably tested? The validity of the polygraph, which measures changes in physiological arousal during a "guilty knowledge" test, is controversial (e.g., T. R. Bashore & P. E. Rapp, 1993; T. P. Cross & L. Saxe, 1992; D. T. Lykken, 1998; J. P. Rosenfeld, 1995; R. Steinbrook, 1992). One alternative to the polygraph examines event-related potentials recorded during a memory interference task (L. A. Farwell & E. Donchin, 1991). The present study extended this paradigm to determine whether response times (RTs) can accurately identify participants possessing specific guilty knowledge. Results from Experiment 1 showed that RT alone can reliably discriminate "guilty" from "innocent" participants. Experiments 2a and 2b indicated that an RT-based paradigm is more resistant to strategic manipulation than previously suggested (Farwell & Donchin, 1991). This RT-based paradigm may be a viable alternative to the polygraph for detecting guilty knowledge.