The authors performed a meta-analysis based on 169 conditions, gathered from 80 laboratory studies, to estimate the validity of the Guilty Knowledge Test (GKT) with the electrodermal measure. The overall average effect size was 1.55, but there were considerable variations among studies. In particular, mock-crime studies produced the highest average effect size (2.09). Three additional moderators were identified: Motivational instructions, deceptive ("no") verbal responses, and the use of at least 5 questions were associated with enhanced validity. Finally, a set of 10 studies that best approximated applications of the GKT under optimal conditions produced an average effect size of 3.12. The authors discuss factors that might limit the generalizability of these results and recommend further research of the GKT in realistic setups.

The present study provides a first attempt to compare the validity of the respiration line length (RLL) and skin resistance response (SRR) amplitude in real-life criminal guilty knowledge tests (GKTs). GKT records of 40 innocent and 40 guilty Ss, for whom actual truth was established by confession, were assessed for their accuracy. When a predefined decision rule was used and inconclusive decisions were excluded, 97.4% of the innocent Ss and 53.3% of the guilty Ss were correctly classified with the SRR measure. For the RLL measure, the respective results were 97.2% and 53.1%. The combination of both measures improved detection of guilty Ss to 75.8% and decreased detection of innocent Ss to 94.1%. The combined measure seems to be a more useful means of identifying guilty suspects than each physiological measure alone. The results elaborate and extend those obtained in a previous field study conducted by Elaad (1990).

Call for Nominations for Developmental PsychologyThe Publications and Communications Board has opened nominations for the editorship of Developmental Psychology for the years 1993-1998. Ross D. Parke is the incumbent editor.Candidates must be members of APA and should be available to start receiving manuscripts in early 1992 to prepare for issues published in 1993. Please note that the P&C Board encourages more participation by members of underrepresented groups in the publication process and would particularly welcome such nominees. To nominate candidates, prepare a statement of one page or less in support of each candidate. Submit nominations to

Two mock-crime experiments were designed to examine the effects of question repetition and variation on the efficiency of the guilty knowledge test. In the first experiment, two factors (single vs. multiple questions, and high vs. low motivation) were manipulated and in the second experiment, which was an analog study conducted in a police laboratory using field equipment, only the first factor was examined. Similar detection efficiencies were obtained in both experiments when a single question was repeated 12 times, and when each of four different questions was repeated 3 times. The results also showed that accumulating information across repetitions and across physiological measures tended to increase detection efficiency and reduce false positive errors. The results of Experiment 1 suggest that motivation to avoid detection may be associated with better detection efficiency.

Two independent experiments were designed to investigate the effects of motivation to deceive and the type of verbal response on psychophysiological detection using the Guilty Knowledge Technique. The first was a field experiment in which 72 subjects were randomly assigned to 8 experimental conditions. These conditions were created by a 2 x 4 factorial design (two motivational states crossed with four verbal response modes--affirming, denying, repeating, or no verbal response to questions about personal information). The second experiment was a laboratory experiment in which 160 students were assigned to the same 8 conditions. Results of both experiments indicated that highly motivated subjects were detected better than less motivated subjects. The act of lying was associated with enhanced differential responsivity, but no effects were obtained for verbal response versus no response or for variable versus standard verbal response. Differential responsivity tended to decline when questions were repeated. The first experiment revealed a clear advantage of electrodermal measures over respiration and cardiovascular measures. The results were discussed in relation to previous findings, a new theoretical formulation, and practical implications.