Credibility Assessment - an overview

A wide variety of practitioners use credibility assessment to inform critical decisions. The criminal justice community need to determine the veracity of suspects and witnesses. Special operations forces need to assess insider threats, indigenous personnel and detainees. Intelligence agencies need to screen individuals who may have access to sensitive information to determine whether they pose an insider threat or other risk. To date, professionals in these communities rely on a variety of methods - interview techniques, mental health assessment, and the polygraph. Over the past 20 years a large body of scientific data has shown that many of these methods lack scientific validation or operational rigor in specific applications, particularly when the subject is mentally unstable or has an ideological basis for dissimulation. In addition, most are based on a model of lying that assumes a deceptive person will exhibit signals of fear, alarm or anxiety when telling a lie.   As a result, screening has failed to detect many—perhaps most—individuals who have deliberately compromised national security. Most recently, screening failed to detect deception and mental instability in the cases of Edward Snowden and Aaron Alexis, the Navy Yard shooter. In addition, insider threats have not been detected in a reliable manner during the conflict in Afghanistan.
Polygraph techniques have been applied for over 60 years in essentially unchanged form, despite the poor reliability in detecting deception. For example, the National Academy of Sciences called the validation of the polygraph “scanty and scientifically weak.” Specifically, their report states, ”Polygraph research has not developed and tested theories of the underlying factors that produce observed responses.” In other words, there is poor understanding of the connection between a physiological response and underlying psychological states. Further, most attempts to validate the polygraph have involved mock crime scenarios in laboratory settings involving individuals who would be unlikely to otherwise commit crimes or intelligence breaches. Cross-cultural studies and field studies of real-world subjects are almost non-existent.
In this context, validity has a scientific meaning. “Validity is an overall evaluative judgment of the degree to which empirical evidence and theoretical rationales support the adequacy and appropriateness of interpretations and actions on the basis of test scores or other modes of assessment.” The National Academy of Sciences report on polygraph outlined several aspects of validity as it relates to credibility assessment tools, including test-retest reliability, inter-rater reliability, internal consistency, criterion validity (i.e., accuracy), and construct validity. Construct validity is the extent to which explanatory theories account for the performance of a test and may include issues related to the environmental context. Most validation studies of credibility assessment have used artificial elements to simulate actual jeopardy or lack a concept of operations or structure for application. Thus, construct validity has been a major weakness in the field.
 
Novel Credibility Assessment Methods

Although there have been minimal federal investments in the development of credibility assessment, nonetheless many novel approaches have been developed that hold promise to improve future practice. Some of these methods are based on a theory of operation similar to polygraph. They assume guilty knowledge on the part of the subject that will alter the physiological responses of the subject upon examination. These methods include non-contact polygraph, infrared imaging, voice stress, and fidget response, among many others. One can speculate that improved polygraph-like examination may be possible by the adoption of these techniques to minimize the intrusiveness of polygraph examination, extend the environments in which “guilty knowledge” methods may be applied, and—presumably—improve accuracy through the adoption of metrics that are orthogonal to polygraph measurement protocols. Unfortunately, none of these methods have proven to be effective in independent studies. For example, a study among arrestee populations showed that voice stress analysis was no better than chance at detecting deception about recent drug abuse when compared with urinalysis results.
More promising approaches rely on different underlying theories. A deceptive individual—regardless of their motivation—requires greater cognitive load to maintain a deception than to tell the truth. Thus, interview techniques or tasks that enhance the underlying cognitive load – whether by requiring the individual to make a drawing of a scene, recount events in reverse or sort between competing stimuli—make it more difficult for a person to maintain a story or deception. Further, research over the past decade indicates it is possible to detect cognitive load through analysis of language, measures of physiology and of brain activity. For many years, police agencies have relied on cognitive interviewing, a lengthy process which is based on cueing individuals with details from an event and other strategies to enhance accurate memory recall. In general, modified cognitive interviewing (MCI) shortens the process to a limited number of memory prompts (including visual, auditory, personal feelings and temporal reversal), uses a more informal interview approach, and emphasizes analysis of speech content and other indicators of cognitive load. MCI has been demonstrated to be more effective than the judgment of experience human investigators and potentially superior to polygraph examination. Forced-choice testing can complement MCI or other approaches through accurate and innovative screening of large numbers of individuals. In forced-choice testing, the subject is given a limited number of options, such as a lineup of pictures that includes a possible target known to the subject. Those with hidden knowledge are much more likely to exclude the target than others, thus permitting screening and providing investigative insight. These and related techniques may be amenable to wide adoption in many circumstances, including as part of a program of ongoing vetting of cleared individuals as anticipated by the Office of the Director of National Intelligence.
Some attention has also been given to micro expressions, which are very brief facial expressions, lasting just fractions of a second, that are presumed to reflect emotional reactions. Presumably, the micro expression will manifest even if the subject is concealing the emotion, whether that intent is deliberate or unconscious. Therefore, micro expressions may be a useful means to detect deception using automated tools, trained examiners, or even after-the-fact video analysis.
Finally, neuroscience may provide some options for specific applications or elucidation of mechanisms involved in other approaches. Functional MRI examines cognitive load by directly measuring brain activity in the prefrontal and parietal lobes. This builds on the psychological understanding of cognitive load during deception described above. The technique is now marketed commercially. (Note: Only No Lie MRI is currently promoting fMRI for this purpose. Cephos no longer offers this service.) Other approaches rely on specific brainwave patterns, such as the P300 recognition response, an approach with a long history and sometimes referred to as brain fingerprinting. This brainwave pattern arises when an individual recognizes an image or idea in sensory stimuli. Brain fingerprinting is based on the theory of concealed information. For example, if an individual is shown a picture of a crime scene, then the P300 response may be detected if the person has prior, presumably concealed knowledge of the crime.  One of the advantages of employing techniques that reveal activity in the human brain is that they potentially enhance the ability to determine which types of activities in the brain are associated with various types of deception. A significant disadvantage to fMRI and other types of brain measures is that the counter-measures are not difficult (for example breathholding, moving, thinking of something else) and the paradigm for which they seem most relevant is the guilty knowledge paradigm. Also, direct brain imaging raises concerns among civil libertarians about the potential for abuse of privacy among non-cooperative subjects. That said, they may show promise for the vetting of employees and other willing participants. In addition, these analytical methods may elucidate the cognitive processes involved in deception that may be revealed by other, less intrusive means.
For more information about credibility assessment or access to Coptech LLC's training and consulting services, please see coptechllc.com.