Increasing the trial size of the Forced Choice Test by expanding the number of answer alternatives

Abstract The Forced Choice Test (FCT) is considered as a memory detection test that can be used in criminal investigations. However, one problem in its application is that it is difficult to secure a sufficient number of questions that can be formulated based on evidence. In this study, we proposed a modified version of the FCT as a memory detection test. Modified FCT uses fewer pieces of criminal information than typical FCT by expanding the number of answer alternatives for each question and creating multiple unique pairs of answer alternatives for a single question. We subjected participants to a mock crime followed by a typical FCT or our novel FCT, which relies on less information. We demonstrate that both FCT types have similar detection accuracies. Hence, the modified FCT may improve the applicability of FCT as a memory detection tool because fewer evidence is needed. We discussed the characteristics of the modified FCT from the viewpoint of the participants’ strategy and detection efficiency.