1. Eye Tracking measures and response accuracy
as measures of detection of feigning
Danielle M. Ploetz, Martin L. Rohling, Melissa N. Womble, Kelley L. Drayer, & Michelle, Lankey
Department of Psychology, University of South Alabama, Mobile, AL
Analysis Method by Subject
Genuine
Correct
Incorrect
Feigning
Purpose
The goal of the study was to further analyze data collected using eye measurements while taking the Word Memory Test (WMT; Green, 2003) in both a genuine and feigning performance. Specifically, we further examined the data if the subject had correctly responded in the genuine condition.
Hypotheses
S’s in the feigning condition who responded correctly to items in the genuine condition will have higher fixation counts than when they responded correctly in the genuine condition.
S’s in the feigning condition who responded correctly in the genuine condition will have longer fixation durations than when they responded correctly in the genuine condition.
S’s in the feigning condition who responded correctly in the genuine condition will have longer dwell time than those in the genuine condition who responded correctly to the items.
Results
Refer to table above for a better understanding of the analysis method. The number of initial fixation counts and total fixation counts were less for the genuine correct when compared to the feigning condition with incorrect responses (p = & < .0001, respectively). First fixation duration was less (p =. 034) for the genuine condition with correct responses. Last fixation duration was longer in the feigning condition with incorrect responses (p = .0002). Dwell time was also significantly longer in the feigning condition with incorrect responses(p < .0001).
Discussion
Eye movements while engaged in the WMT were significantly longer in the feigning condition than the genuine condition. We selectively compared the trials in which the subject in the genuine condition obtained correct responses to those in which the subject, when in the feigning condition, obtained incorrect responses. The results indicate that eye movements are different when the subject is performing genuinely and are responding correctly as opposed to when the subject is intentionally providing incorrect responses. This study is limited since it is an analog study with a limited number of subjects. Future research should examine the utility of eye tracking in specific populations, such as TBI or Dementia assessments. It is currently unknown if the results are generalizable to different age groups.
Method
There were 27 psychology undergraduates who were included for analyses, 5 males and 22 females, M age 20.4 (SD = 3.5). Race of S’s: 66% Caucasian, 19% African American, 11% Asian, and 4% other. Some subjects were excluded due to unforeseen errors with program. S’s wore an EyeLink II head piece to record eye movements. The WMT was administered via computer per the User Manual. It was assumed that those who had correctly identified the word in the genuine condition had learned the word. Those that then incorrectly identified the target word were assumed to have intentionally misidentify, thus feigning memory impairment.
ANOVA RESULTS OF EYE TRACKING MEASURES
Genuine (Correct only)
Feigning (Incorrect within Genuine Correct only)
Overall
Variable M sd p d
1. Total Correct (%)
98.0
2.6
58.1
14.3
< .0001
-3.88
2. Fixation Duration First Fix (ms)
269.3
51.7
310.4
82.5
.0034
0.60
3. Initial Fixation Count per Trial
1.54
0.31
2.06
0.67
.0002
0.99
4. Fixation Duration Last Fix (ms)
270.4
41.5
329.6
84.1
0.89
5. Dwell Time (ms)
399.1
92.4
607.4
207.5
<.0001
1.30
6. Total Fixation Counts
4.84
6.44
1.64
1.81
Special thanks to Dr. Mark Yates for the use of his lab and assistance with the EyeLink program.
Citation: Ploetz, D. M., Rohling, M. L, Womble, M. N., Drayer, K, & Lankey, M. (2011, June). Poster presented at the 9th Annual AACN Conference Washington, DC. Addresses: and