Purpose. In this experiment we examined whether an unanticipated spatial task couldincrease the differences between lying and truth telling groups of adolescents. In addition,we explored whether there are some elements of such a spatial task that elicit morediagnostic cues to deception than others.

Methods. In groups of three, adolescents (N = 150, aged 13–14) either experienced(‘truth tellers’) or imagined (‘liars’) an event. In subsequent individual interviews, theadolescents were asked to provide both a general verbal description of the event (theanticipated task), and a spatial description by making marks on a sketch (the unanticipatedtask). Next, adults (N = 200) rated the degree of consistency between either the generaldescriptions or the spatial descriptions from the adolescents in each triad.

Results. The differences between liars and truth tellers were larger for the spatialmarkings (the unanticipated task) than for the general verbal descriptions (the anticipatedtask). Importantly, as predicted, the difference between lying and truth-telling triads wasmost manifest for markings of salient (vs. non-salient) aspects of the event.

Conclusions. The results suggests that (a) using spatial tasks may be a useful tool fordetecting deception in adolescents, but that (b) the assessment of credibility should onlydraw on the salient aspects of the unanticipated spatial task.