Effectiveness of pupil diameter in a probable‐lie comparison question test for deception

Abstract

Purpose. There were three objectives of this study: (1) To assess the possibility of using pupil diameter as an index of deception in the context of a comparison question polygraph test.(2) To determine if pupil diameter would make a significant contribution to an optimal multivariate classification equation in combination with the traditional predictor variables used in field polygraph practice. (3) We explored the possibility of replacing one or more of the traditional predictor variables with pupil diameter.Methods. We used a laboratory mock crime experiment with 24 participants, half of whom stole $20 (US) from a secretary's purse. Participants were tested with a comparison question test modelled after standard field practice. Physiological measures were taken with laboratory quality instrumentation. Features were extracted from the physiological measures. Those features were subjected to a number of different statistical analyses.Results. Innocent participants showed larger increases in pupil diameter in response to probable-lie questions than to relevant questions. Guilty participants did not show differential responding to the question types. The additional of pupil diameter to a multivariate classification model approached, but did not reach significance. Subsequent analyses suggest that pupil diameter might be used to replace the traditional relative blood pressure measure.Conclusions. Pupil diameter was found to be a significant predictor variable for deception. Pupil diameter may be a possible replacement for the traditional relative blood pressure measure. Additional research to explore that possibility would seem to be warranted.Despite decades of research, there is a long-standing and heated debate on the validity of the comparison question test (CQT) for psychophysiological deception detection

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

“…Consistent with the cognitive workload hypothesis, deception researchers have also found increases in pupil size associated with deception (Berrien & Huntington, 1943; Dionisio, Granholm, Hillix, & Perrine , 2001; Heilveil, 1976; Lubow & Fein, 1996). Indeed, pupil responses to statements on polygraph tests can be used to discriminate between truthful and deceptive participants (Bradley & Janisse, 1981), and may be at least as diagnostic as electrodermal responses (Webb, Honts, Bernhardt, Kircher, & Cook, 2009). Thus, we predicted that participants would show greater increases in pupil diameter in response to statements answered deceptively than to statements answered truthfully.…”

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

“…Despite these caveats, further investigation is warranted. One interesting alternative for avoiding dependence on overt responses is to use more complex stimuli (e.g., sentences or picture arrays) and examine ocular scan-patterns during the CKT (e.g., Webb et al, 2009a,b; Kircher et al, 2010; Cook et al, 2012). …”

“…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).…”

A review of the polygraph: history, methodology and current status

“…Proponents of the CQT continue to research the applications and possible improvement to the tool (see Ginton, 2013;Horvath & Palmatier, 2008;Webb, Honts, Kircher, Bernhardt, & Cook, 2009). However, considering the reported flaws of its underlying assumptions, it is uncertain whether its accuracy or academic standing will significantly improve in the near future, unless the technique is modified to function in concordance with a more grounded theoretical basis.…”