decision-making in lie detection

Posted comment on ´Expertise in Deception Detection Involves Actively Prompting Diagnostic Information Rather Than Passive Behavioural Observation` by T. Levine, D. Clare, J. Blair, S. McCornack, K. Morrison and H.Park published in Human Communication Research, 40 (4) 442 DOI: 10.1111/hcre.12032


According to Levine and his colleagues, the fundamental principle of lie detection is more than just spotting the signals of a lie told. Successful detection involves strategic questions by the interrogator in order that the truth or lie will be revealed. In the first part of their study, 33 students working in pairs with a planted accomplice took part in a quiz with a cash prize. During the quiz the researcher left the room giving the students the chance to cheat if they wished. Four did look at the answers. After the quiz the student participants were asked questions by expert interrogators about how they knew their answers were correct, the method of cheating if it was desired and the view of their partner to the cheating situation. The students were then threatened with an investigation if they had cheated if their purpose was to ruin the study, but cheating for money would be regarded more favourably. During the interrogation all four cheaters admitted their guilt and they were correctly identified by the interrogators. Even other students using tapes of the experiment identified the cheaters with over 90% accuracy demonstrating that with strategic questioning most people can interpret the answers. This was further supported by a repeat study with 89 students, 40 cheaters and 5 expert interrogators leading to 34 out of the 40 cheaters confessing with some interrogators having 100% accuracy. In this case the students who were shown the tapes achieved over 93% accuracy at identifying those who had cheated during the quiz.


There are two sides to lie detection that of the interrogator and the interrogated. In this case, the interrogators are experts in their field and the interrogated are students or researchers. The study involves the premise that for the students the financial reward for winning the quiz is higher than the esteem of the result and therefore they would take any chance offered of improving the odds of winning. The results showed that in the first study only 4 out of 33 (12%) actually did cheat when given the opportunity. An unknown number may have considered it, but for whatever reason did not carry out the act. Those that cheated admitted it under questioning, but it is assumed that they would not admit to this at the outset for fear of being disqualified. Therefore, any straightforward question like, ´Did you cheat?` would be unlikely to reveal the truth at the beginning. The other 29 preferred to rely on their own skill (eg memory and processing capabilities) to win the quiz.
To establish whether any student had cheated or not, questions were asked that could give an expert interrogator clues to their identity. The interrogator would use a variety of skills to establish the baseline and truth including visual and auditory capabilities, logic and reasoning and even probably intuition relying on quick, unconscious processing of the answers given. He would look at the wording of the answers, hesitation, body language (there are over 30 signals), the use of ´rehearsed` replies, implausible reasoning for example and use his capabilities of logic and reasoning and then decision-making to make a judgment of whether the student had or had not cheated during the quiz. For example in reply to question 1 how the student knew his answers were correct then it is likely that the student would give one or a number of reasons eg. previous knowledge, use of logic and reasoning, even guess work and intuition. The interrogator would not only be listening to the answer given, but also the student`s body language and attitude and he would analyse the input both consciously and subconsciously in order to come to a decision whether the truth or a lie had been told. Perhaps looking at gut instinct vs experience/training, subtle signs vs obvious deflections/lies, topic avoidance/few words vs verbosity or abnormal/unexpected character changes during the test vs normal character changes due to stress for example. Not only does the interrogator need cognitive capabilities, but so does the cheating student since he intends to deceive with his answers. Therefore, he is conscious of his replies, even body language. Other non-cheating students may also give false-positive signals for a variety of reasons and this too, must be registered.
Each question asked adds to the picture the interrogator has of the nature of the student and whether in this case he cheated or not and he relies on his knowledge and skill at determining the truth. After four questions, structured so as to ascertain the correct situation, the interrogator makes the decision. The questions are so clear that even other students could determine who the cheaters were. These students used their own knowledge, skills at reading body language, gut feelings to interpret what they saw and heard and this implies that the skills for ascertaining the truth are available to most people if provided with the relevant information. The strategies used by the expert interrogators to derive their decision may be different from the student observers, eg the former may rely on comparisons between observed and expected under different situations, whereas the latter on observed and empathic answers (all observers are innocent and therefore they are comparing what the students say and do to what they think they would say and do in the same situation), but the conclusion is the same. However, with lie detection and other decision-making situations, this experiment supports the view that the skill lies in the bringing together of the appropriate information in this case through strategic formatting of the questions. It is here where the experience and abilities of the expert interrogator lies using tried and tested strategies to bring about a successful result. Without the correct questions, it is unlikely that the student observers would obtain the same performance at identifying the cheaters.

Since we`re talking about the topic……
….can we assume that priming the students to answer the questions would influence the results with cheaters being able to conceal their identities more and non-cheaters giving more false-positive results?
….if students were given dopamine-enhancing drugs before the study would their answers be influenced by the enhanced emotion-influencing neurotransmitter and higher prefrontal cortex and basal striatal activities?
…if interrogators were given dopamine-enhancing drugs before the study would their ability to assess information and make decisions based on probability, risk and value be influenced by the change in prefrontal cortex activity?

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