This dissertation examines the processing demands associated with motor responding and verbal statements during deceptive (or deceptive-like) behavior. In the first set of studies presented in Chapter 2, participants' motor movements in a false response paradigm revealed signatures of competition with the truth. In a second set of studies presented in Chapter 3, deceptive participants used language that reflected cognitive and social demands inherent to various types of deception. In evaluating both motor and verbal cues, this dissertation provides a comprehensive, multi-modal approach to better understanding the cognitive processes underlying deception.

In conducting the motor responding studies, participants' arm movements were analyzed as they navigated a motion tracking device (computer-mouse, Nintendo Wiimote) to visually co-present response options, where the “true” option acts as a competitor to a false target. In an initial study, competition during deceptive responding was shown to be much greater than during truthful responding. In two follow-up studies, the introduction of various task-based cognitive demands was shown to systematically modulate response performance. Specifically, these studies suggest that an intention to false respond early in question presentation will amplify competition effects, and that false responding to information in autobiographical memory is much more difficult than responding to information in general semantic memory.

In the studies analyzing verbal statements, the focus is turned to large-scale linguistic analyses using automated natural language processing tools. In the first study, changes in language use were identified between deceptive and truthful narratives using six psychologically relevant categories. A major finding was that the language of deception is adapted to facilitate ease of cognitive processing.

In a second study, the indicative phrasing and semantic content of deceptive texts was extracted using a contrastive corpus analysis, whereby indicative features are defined by their frequent use in one corpus while being infrequent in a comparative corpus. Two contexts of deception were evaluated. In the first context of computer-mediated conversations , deceivers used a range of unique thematic elements, as in avoiding personal involvement in their narrative accounts. In the second context of attitudes towards abortion, unique thematic elements once again emerged; for example, participants tended to position their arguments in terms of formal law.