The aim of the study was to pro vide fur ther ev i dence of the ac cu racy of in di rect de cep tion de tec tion mea sures and to test the effects of in form ing those en gaged in de tect ing lies of the ac tual rea son for their ob ser va tions. The re sults are im por tant from the point of view of po ten tial ap pli ca tions. The ex per i ment was con ducted in two phases. First, a group of col lege stu dents was asked to de scribe hon estly or dis hon estly four of their ac quain tances. The state ments were vid eo taped. Sec ond, the video-clips were shown to a group of un der grad u ate stu dents ran domly as signed to one of four ex per i men tal groups in which the par tic i pants were asked to as sess: 1) the hon esty of the send ers by an swer ing di rect ques tions; 2) the hon esty of the send ers by an swer ing in di rect ques tions; 3) the send ers by an swer ing in di rect ques tions; 4) the send ers by an swer ing di rect ques tions. The re sults re vealed that par tic i pants were able to dis tin guish be tween truth and lies most ac cu rately when an in di rect ques tion was ap plied and that inform ing lie de tec tors of the real aim of their ac tiv ity did not im pair the ac cu racy of this method. The the o ret i cal con sid er ations and the im pli ca tions for fu ture re search are dis cussed.