Eye tracking as a mean to detect feigned cognitive impairment in the Word Memory Test

Abstract

Eye movements showed initial promise for the detection of deception and may be harder to consciously manipulate than conventional accuracy measures. Therefore, we integrated an eye-tracker with the Word Memory Test (WMT) and tested its usefulness for the detection of feigned cognitive impairment. As part of the study, simulators (n = 44) and honest controls (n = 41) performed WMT's immediate-recognition (IR) subtest while their eye movements were recorded. In comparison to the control group, simulators spent less time gazing at relevant stimuli, spent more time gazing at irrelevant stimuli, and had a lower saccade rate. Group classification using a scale that combined the eye movement measures and the WMT's accuracy measure showed tentative promise (i.e., it enhanced classification compared to the use of the accuracy measure as the sole predictor of group membership). Overall, integration of an eye-tracker with the WMT was found to be feasible and the eye movement measures showed initial promise for the detection of feigned cognitive impairment. Moreover, eye movement measures proved useful in enhancing our understanding of strategies utilized by the simulators and the cognitive processes that affect their behavior. While the findings are clearly preliminary, we hope that they will encourage further research of these promising psychophysiological measures.

Keywords:

• Eye movements
• feigned cognitive impairment
• forensic neuropsychology
• memory and learning
• performance validity test (PVT)
• Word Memory Test (WMT)

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Acknowledgments

The research reported in this paper was completed as part of the second author’s (T.L.) M.A. dissertation, Ariel University, Israel. We would like to thank Dr. Paul Green for his collaboration in the project and helpful remarks. We would also like to thank Asia Mershon, Batia Fink, Chaim Seltzer, Dvir Avivi, Tal Goldman and Lior Sror who aided the project as research assistants and/or as part of their undergraduate psychology studies.

Notes

1 A saccade is a ballistic motion of the eyes that allows them to rapidly move ‎between fixations, periods in which the eyes ‎remain fairly still, and data at that location is processed (Duchowski, 2017; p. 40–43).

2 Details regarding the WMT are not provided to ensure its integrity.

3 For example, the other healthy participants in the current study scored 98.11 ± 3.34 (see Table 1), while healthy participants scored 98.0 ± 2.8 in a study that was included in the WMT's manual (Green, 2005; p. 37).

4 Note that side crossings was not intended to serve as a validity indicator (see, Eye-tracking apparatus and eye movement measures). It was, therefore, not included in the logistic regressions and the ROC curve analyses.

5 The use of multiple strategies was listed by four participants. Therefore, the percentages in the paragraph add to more than 100%.

6 For example, frequency of saccades (i.e., saccade rate; no. saccades per sec) was used instead of number of saccades. Please note that the pupil size was not relevant in this regard, since it could not be measures as either number/duration or frequency (i.e., average pupil size was used in the current study).