Howdy, everyone — Jerry Thomas here. Today I want to talk about a topic that is mighty important to those of us who care about who gets behind the badge: practical strategies for implementing credibility assessment testing in the law enforcement pre-employment process. Getting this right is not just good policy — it is a public safety obligation.
Understanding Credibility Assessment in Law Enforcement Hiring
Credibility assessment testing — using validated instruments to evaluate a candidate's honesty during the hiring process — has been part of law enforcement recruiting for decades. The polygraph has long been the standard tool, but today agencies have more options than ever, most notably EyeDetect, the ocular-motor deception detection technology developed by Converus.
Handler, Honts, Krapohl, Nelson & Griffin (2009) established in their landmark paper — published in the Journal of Police and Criminal Psychology — that law enforcement pre-employment polygraph examinations are best understood as "a decision-support tool intended to add incremental validity to the personnel selection process."[1] Critically, they also warned that using polygraph results alone to disqualify a candidate is a misguided field practice — the instrument works best as one component of a comprehensive evaluation.
That insight — that credibility assessment adds incremental validity rather than serving as the final word — is the foundation every agency administrator should build their program on. With that in mind, here are six practical strategies for implementing a sound credibility assessment program.
1 Choose the Right Tool — or the Right Combination
The first decision is selecting which instrument — or which combination of instruments — best fits your agency's needs, budget, and staffing capacity.
The polygraph is the most established and well-validated tool. Horowitz, Kircher, Honts & Raskin (1997) demonstrated empirically that comparison questions produce different physiological patterns for innocent versus guilty subjects, providing the scientific foundation for the CQT polygraph's pre-employment application.[2] The most comprehensive meta-analysis to date — Honts, Thurber & Handler (2021) — analyzing 138 datasets found a meta-analytic effect size of r = .694 with median accuracy of approximately 86%, confirming the CQT performs well above chance and above human judgment alone.[3]
EyeDetect, developed by Converus with the involvement of Drs. David Raskin and John Kircher — the same scientists credited with computerizing the polygraph — measures involuntary eye behavior including pupil dilation, blink rate, and cognitive load patterns. Field testing has shown EyeDetect accuracy at 85–88% for pre-employment screening, with results generated in under 10 minutes and up to 15–30 tests administered daily by a single proctor.[4] That scalability makes it especially well-suited as a first-stage screening tool.
The strongest approach combines both as successive hurdles — EyeDetect first for fast, cost-effective initial screening, followed by a full polygraph examination for candidates who pass. For more on the science behind successive hurdles, see my earlier post: Successive Hurdles in Law Enforcement Pre-Employment Screening →
Back when yours truly was knee high to a grasshopper, every student had to take a tuberculosis screening test each year — the Mantoux tuberculin skin test (TST). A small amount of tuberculin purified protein derivative was injected into the forearm. Within two or three days a school nurse checked for a reaction. Fast, inexpensive, administered by a nurse.
If there was a reaction, then came the more costly and intrusive follow-up test. That was an efficient, responsible, and cost-reducing strategy. If those in charge had kicked the can down the road, the price of doing nothing could have been astronomical.
Pre-employment credibility assessment works the same way. EyeDetect first — fast, affordable, scalable. Polygraph second — for those who pass. You invest the greater resource only where it is warranted. The math is simple and the logic is sound.
2 Establish Clear Policies and Guidelines
Once you have selected your instruments and process, establishing written policies and guidelines is essential — not optional. Handler et al. (2009) specifically identified poorly constructed policies as one of the primary sources of problems in law enforcement polygraph programs, noting that misguided policies surrounding the use of the polygraph are a leading cause of both inaccurate outcomes and legal exposure.[1]
Your policy should address: when in the hiring process each instrument is administered; who is authorized to administer and score each test; what specific topics will be covered; and how results will be used in the overall evaluation — including that no single test result will serve as the sole basis for disqualification. Transparent, consistent procedures protect your agency legally and ensure every candidate is treated fairly.
3 Invest in Proper Training for Administrators
A credibility assessment program is only as good as the people running it. Polygraph examiners must be trained at an APA-accredited school and maintain their credentials through continuing education. EyeDetect proctors require training and certification through Converus.
Honts & Amato (2007) demonstrated that automation and proper training significantly increase the accuracy of screening polygraph results.[5] The takeaway for administrators: invest in your people, require continuing education, and do not allow credentials to go stale. The technology is only as reliable as the training behind it.
"Polygraph examination targets are most effective when actuarially derived — selecting the issues most strongly associated with increased success in law enforcement training and job performance, not simply what seems intuitive."
— Handler, Honts, Krapohl, Nelson & Griffin (2009)
4 Educate Candidates and Obtain Informed Consent
Every candidate who undergoes credibility assessment testing should receive a clear, plain-language explanation of what the test involves, what will be asked, how long it takes, and how results will be used. Informed consent is both a legal requirement and an ethical obligation.
This transparency also serves a practical purpose. Converus research on EyeDetect has documented that candidates who understand the technology and believe it is accurate are more likely to disclose truthfully — and in many cases, the deterrence effect alone causes applicants with problematic backgrounds to self-select out before testing even begins.[4] That is a benefit that never shows up in accuracy statistics but is very real in practice.
5 Integrate Results Into a Comprehensive Evaluation
No credibility assessment tool — no matter how accurate — should be the sole determinant of a hiring decision. Handler et al. are explicit on this point: using polygraph results alone to disqualify a candidate is a misguided field practice.[1] The instrument's value lies in the incremental validity it adds to an overall evaluation process that also includes background checks, structured interviews, psychological assessments, and reference verification.
Think of credibility assessment as one layer of a comprehensive screening process — a powerful and validated layer, but still one layer among several. When all layers are applied consistently and professionally, you are doing everything within your power to make the best possible hiring decision for your agency and your community.
6 Document Everything and Review Regularly
Maintain thorough documentation of every examination — who administered it, what format was used, what results were produced, and how those results were factored into the hiring decision. This documentation protects your agency in any subsequent legal challenge and provides the data you need to evaluate and improve your program over time.
Set a schedule to review your program annually. Are you using the most current validated formats? Are your examiners current on continuing education? Have best practices in the field evolved? The APA and Converus both publish updated research and guidance regularly — staying current is part of professional responsibility.
References
- Handler, M., Honts, C.R., Krapohl, D.J., Nelson, R., & Griffin, S. (2009). Integration of pre-employment polygraph screening into the police selection process. Journal of Police and Criminal Psychology, 24(2), 69–86. Boise State Open Access → | Springer →
- Horowitz, S.W., Kircher, J.C., Honts, C.R., & Raskin, D.C. (1997). The role of comparison questions in physiological detection of deception. Psychophysiology, 34(1), 108–115.
- Honts, C.R., Thurber, S., & Handler, M. (2021). A comprehensive meta-analysis of the comparison question polygraph test. Applied Cognitive Psychology, 35(2), 411–427. Open Access PDF → | doi:10.1002/acp.3779
- Converus. (2024). Law enforcement pre-employment testing with EyeDetect. converus.com/lepet | Converus. (2024). 12th peer-reviewed publication validates ocular-motor deception detection. converus.com →
- Honts, C.R., & Amato, S. (2007). Automation of a screening polygraph test increases accuracy. Psychology, Crime & Law, 13(2), 187–199.
- Raskin, D.C., Kircher, J.C., Honts, C.R., & Horowitz, S.W. (1988). A study of the validity of polygraph examinations in criminal investigation. Final report to the National Institute of Justice. University of Utah Department of Psychology.
Final Thoughts
Building a credibility assessment program that actually works requires the right tools, solid policies, trained administrators, transparent candidate communication, and honest integration of results into a broader evaluation process. None of those elements is optional — they work together, and weaknesses in any one of them undermine the rest.
If those in charge of law enforcement hiring kick this particular can down the road, the costs — in public trust, officer misconduct, legal liability, and community harm — can be astronomical. The research is there. The tools are proven. The strategies are straightforward. Y'all take care now, and keep upholdin' the law.
If your agency in Texas, Oklahoma, or Kansas is looking to implement or improve a credibility assessment pre-employment program using polygraph or EyeDetect, I am glad to discuss how it works in practice — at no obligation.