Lying, Difficulty of

Are Nonverbal Cues and Cognitive Load Really Indicative of Deception?

Scholarly belief in the difficulty of lying is foundational to past and current theoretical models and research programs of deception detection. Because lying is believed to evoke greater cognitive load, scholars have long suggested using load-related behavioral cues as indicators of deception. For instance, increases in cognitive load often result in longer response latencies (i.e., delays before responding to questions), longer pauses while speaking, increases in speech errors, and increases in the number of filled pauses (including “umm” and “ah”). Because lying generates greater cognitive load than truth-telling, scholars presume that these behavioral indicators should accurately distinguish liars from truth-tellers, thus allowing for detection.

Empirical research, however, has failed to document that nonverbal behaviors indicative of cognitive load differentiate honest and deceptive communication. In fact, behavioral signatures relevant to cognitive difficulty for truth-tellers and liars appear to be quite similar; therefore, such signatures are not useful for lie detection.

Given that behavioral cues signaling cognitive load do not reliably differentiate truths and lies, some researchers now suggest that increasing load beyond what would be “normal” for liars and truth-tellers constitutes an efficacious way of detecting deception. The reasoning is twofold: if lying can be made too difficult, then people will either (1) just be honest or (2) give themselves away. Strategies used by these researchers for increasing the cognitive load of liars include asking unexpected questions and asking people to provide information in reverse chronological order.

A small subset of scholars, however, has begun to challenge the orthodoxy that lying is intrinsically harder than truth-telling. Bella DePaulo's work in the late 1990s was seminal in this regard. She had respondents record in a diary the everyday lies they told in conversations. Contrary to lies being planned, arousing, involving, and effortful, she found that the average lie was unplanned, casual, and (importantly) involved minimal cognitive effort. Subsequent to this work, Steven McCornack offered a scathing indictment of what he called the “cognitive load hypothesis” (i.e., the argument that lying always evokes high cognitive load), noting that lying within many contexts involves cognitive efficiency advantages over truth-telling.

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