Charting the behavioural state of a person using a backpropagation neural network

This paper describes the application of a backpropagation artificial neural network (ANN) for charting the behavioural state of previously unseen persons. In a simulated theft scenario participants stole or did not steal some money and were interviewed about the location of the money. A video of each interview was presented to an automatic system, which collected vectors containing nonverbal behaviour data. Each vector represented a participant’s nonverbal behaviour related to “deception” or “truth” for a short period of time. These vectors were used for training and testing a backpropagation ANN which was subsequently used for charting the behavioural state of previously unseen participants. Although behaviour related to “deception” or “truth” is charted the same strategy can be used to chart different psychological states over time and can be tuned to particular situations, environments and applications. We thank those who kindly volunteered to participate in the study.