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We investigated whether or not liars, as compared to truth tellers, would have an attentional bias for concealed information. To identify attentional avoidant patterns in liars, we measured their eye movements with an eye tracker. The participants were 54 students who had made their own choice about which of 2 groups they would join: the guilty group (n = 27), who were presented with a theft-crime mission to perform, or the nonguilty group (n = 27), who were presented with a legal mission. During the deception detection process, the eye tracker was used to measure participants' attentional bias according to their eye movements while they were presented with pairs of crime-relevant, crime-irrelevant, and neutral stimuli. Results showed that both the guilty and nonguilty groups speedily detected crime-relevant stimuli, but the guilty group became avoidant toward these stimuli, whereas the nonguilty group did not display an avoidant pattern.
Keywords: guilt, lying, deception detection, eye movement, attentional bias, attentional avoidance, orienting response.
Liars, as compared to truth tellers, often reveal behavioral signs of lying, such as looking up and to the left, and making less eye contact (Matsumoto, Hwang, Skinner, & Frank, 2011). In crime investigations, suspects who know specific crime-related details direct their senses to concealed information with the orienting response (OR; Sokolov, 1963). OR is the response of the physiological and behavioral systems to novel or significant stimuli with signal value. That is, people who are guilty show a stronger OR to concealed information items than to other items, whereas all items elicit equivalent responses from truth tellers. Dilated pupillary size, fewer eye blinks, and different gaze fixations have been used as ORs to differentiate between those who are guilty and those who are innocent (Leal & Vrij, 2010; Webb et al., 2009).
Gaze fixations can identify whether or not a person is already familiar with certain items (Ryan, Hannula, & Cohen, 2007). Schwedes and Wentura (2012), who analyzed the duration of initial gaze fixation to distinguish between participants who were guilty or innocent of a mock theft, found that liars obviously recognized concealed information items and fixed their gaze longer on them than they did on other items. However, gaze fixation patterns with regard to concealed information are more complex than involuntary responses....