Back to the future: asking about mental images to discriminate between true and false intentions.

In this study we asked participants to mentally travel back to the future. The participants were asked to remember and report on a mental image of the near future. We predicted that participants who, during an interview, told the truth about their intentions would differ in their descriptions of their mental images compared to participants who lied about their future intentions. We found partial support for this overarching assumption. More specifically, we found that more truth tellers than liars reported to have had a mental image activated during the planning of their intentions. We also showed that liars (vs. truth tellers) found the question on the mental image more difficult to answer. However, they did not differ in other aspects (number of words and amount of details reported, and subjective perception of the mental image activated). The suspects were interviewed twice, with an interval of one week, and in line with our prediction we found that liars' (vs. truth tellers') reports were less consistent over time. This study departures from episodic future thought and aims to contribute to the development of a scientifically based interview protocol for discriminating between true and false intentions.