The effects of a physical (pressing the toes to the floor) and a mental (counting backward by sevens) countermeasure on the concealed knowledge test (CKT) were examined in a mock crime experiment with 40 subjects. Some knowledgeable subjects were informed about the nature of the CKT and were trained in the use of a countermeasure, whereas others remained uninformed. All subjects were offered a monetary reward if they could produce a truthful outcome. Subjects were tested using standard field techniques and instrumentation. The physical and, to a lesser extent, the mental countermeasures reduced the accuracy of the CKT. These results clearly demonstrate that the CKT has no special immunity to the effects of countermeasures.

A series of 4 experiments were conducted to (a) determine the willingness of children to lie in a realistic setting, (b) compare judgments of credibility from both lay evaluations and Criterion-Based Content Analysis (CBCA), and (c) examine the effects of expert testimony regarding Statement Validity Assessment on mock jurors who were asked to make evaluations of the children\u27s statements. In Experiment 1, 81% of children who witnessed a research assistant steal a textbook made accusations against the thief (truthful), 69% of children who did not witness the theft accused the research assistant of the theft following prompting by significant others, and 56% of the children who witnessed a significant other steal the textbook incorrectly accused the research assistant following a request from their significant other. Using the statements obtained from the children in Experiment 1, Experiments 2 and 3 found that classification accuracy of lay evaluators was significantly poorer than expert application of CBCA, which resulted in 89% classification accuracy. Finally, brief exposure to CBCA expert testimony appeared to have no benefits on mock jurors\u27 assessments of credibility of the children\u27s statements in Experiment 4. Implications for North American legal systems are discussed

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