Eye Movements and Pupil Size Reveal Deception in Computer Administered Questionnaires

Abstract

An oculomotor test is described that uses pupil diameter and eye movements during reading to detect deception. Forty participants read and responded to statements on a computerized questionnaire about their possible involvement in one of two mock crimes. Twenty guilty participants committed one of two mock crimes, and 20 innocent participants committed no crime. Guilty participants demonstrated speeded and accurate reading when they encountered statements about their crime and increases in pupil size. A discriminant function of oculomotor measures successfully discriminated between guilty and innocent participants and between the two groups of guilty participants. Results suggest that oculomotor tests may be of value for pre-employment and security screening applications.

Lyin' eyes: Ocular-motor measures of reading reveal deception.

“…Consistent with previous research, guilty participants in both experiments showed greater increases in pupil diameter for statements answered deceptively than for statements answered truthfully (e.g., Berrien & Huntingdon, 1943; Bradley & Janisse, 1981; Dionisio et al, 2001; Heilveil, 1976; Kircher, Podlesny, Bernhardt, Bell, & Packard, 2000; Lubow & Fein, 1996; Webb et al, 2009). The reading behaviors of guilty participants were more surprising, however.…”

“…As in previous research, deception in this experiment was associated with greater increases in pupil size (e.g., Bradley & Janisse, 1981; Webb et al, 2009). Participants who stole $20 showed stronger pupil responses to statements about the $20, whereas participants who stole credit card information showed stronger pupil responses to statements about the credit card.…”

“…However, no effect of repetitions was observed on pupil responses in Experiment 1 (for a similar finding, see Webb et al, 2009) The present results may indicate that the pupil changes in these deception tests were mediated by the parasympathetic nervous system and mostly reflect changes in cognitive load (Bradley et al, 2008). Alternatively, the three repetitions of the statements may have provided insufficient opportunity to observe effects of trials on evoked pupil responses.…”

“…Instead, guilty participants responded faster, made fewer fixations, and spent less time reading and reading statements about the crime they committed than statements about another crime or neutral statements. Although these effects were not expected, they have since been replicated in two other independent groups of guilty participants in a mock crime experiment (Webb, Hacker, et al, 2009). …”

Combining Blink, Pupil, and Response Time Measures in a Concealed Knowledge Test

“…Because of such results, pupil-size has been explored as a measure of deception (Berrien and Huntington, 1942; Heilveil, 1976; Janisse and Bradley, 1980; Lubow and Fein, 1996; Dionisio et al, 2001; Webb et al, 2009a,b). Fluctuations in pupil-size can be highly reliable even when small in magnitude, with researchers reporting robust effects as small as 0.1 mm (Hakerem and Sutton, 1966) and 0.015 mm (Beatty, 1988).…”