DETECTION OF CONCEALED INFORMATION
Another specialised polygraph technique allows the investigator to determine if a crime suspect recognizes crime relevant information. The Concealed Information Test (CIT), or sometimes referred to as the Guilty Knowledge Test, uses a set of multiple-choice questions which refer to crime-specific details of the investigation in hand. For example in the case of a drive by homicide was:
1. Relevant Items: crime-related (e.g. “black Mercedes car).
2. Irrelevant Items: similar and plausible, but not crime-related alternatives (e.g. “Audi, BMW, Jaguar, Maserati, Aston Martin .”).
The assumptions being that those suspects who possess “guilty knowledge” will recognize the crime-relevant information and react more strongly to relevant items than to irrelevant items; and those with no “guilty knowledge” will have no differential reactions to either relevant or irrelevant items. The advantage, therefore, is that for innocents there is a very low risk of being misclassified as “guilty” Research has found that the accuracy is in the region of a 95% hit rate, and that most studies reported no false positive results, i.e. misidentifying the innocent as guilty. This test is considered to be a standardised and highly accurate psychophysiological method for deception detection, and is based upon the orienting reflex.
The Concealed Information Test is used for the evaluation of all types of suspects in both white crime and criminal cases.. This test is widely accepted as a valid procedure by the scientific community around the world, and may meet what constitutes scientific evidence in legal proceedings. Please note that the concealed information test relies upon the establishment the information is only known by the ‘guilty’ person, therefore it is crucial to ensure that ‘knowledge’ is kept hidden from the media or third parties.
The CIT can be used to good effect when a child abduction case is revealed as a homicide investigation. Notably, the investigators employ the CIT to narrow down multiple suspects.
We recommend that the Concealed Information Test be used when examining offenders with psychopathic traits as the orienting response is likely to enhance their unusually low lability.