Jimmie Ray Slaughter was executed by the state of Oklahoma on March 15, 2005, for murdering a former girlfriend and their child. Slaughter continually professed his innocence, and even though he was put to death, many still question whether he was guilty.One of the controversies around his condemnation was the result of a “brain fingerprinting” test that indicated that Slaughter had no recollection of the crime. Brain fingerprinting measures in milliseconds the subjects’ reactions to words, items or pictures presented on a computer screen. The process is based on the theory that the brain elicits different responses based on whether the information presented is recognized or not.
The ambiguity of the Slaughter case, along with the questioned accuracy of lie detector tests, underscores not only the need for greater certainty in criminal prosecutions, but also the ability of forensic psychology to provide some of the answers. SNHU psychology Professor Peter Frost, with student Roland Denomme and former students Michael Adie ’09, Annabel Lahaie ’08, Angel Sibley ’09 and Emily Smith ’08, conducted a study that could potentially add another dimension to lie detection by investigating the subconscious thought processes involved in deception.According to Frost, the results of the study suggested that people react negatively to lying and reinforced the idea that lying takes longer for the brain to process. “We were looking to see if subjects had a negative subconscious attitude towards what they lie about,” said Frost.
In the experiment, a large group of students was asked to memorize correct and incorrect answers to various questions. They were then asked to give either the correct or the incorrect answers in a subsequent interview. Finally, the Implicit Association Test was administered to the students, with interesting results.
The IAT has typically been used to detect underlying prejudices by measuring the time in milliseconds it takes for someone to associate positive or negative words with images or words on a computer screen. Participants will usually take longer to associate positive words with something they dislike or harbor a subconscious negative attitude toward. What Frost did was combine the IAT with past research that showed that lying slows down the cognitive process to create a way to potentially use the IAT to detect deception.
Students were shown images or words pertaining to the questions they had previously studied and possibly lied about. They were then asked to press one of two response keys. Students would press one key to associate positive words with the images or words on the screen, and the other to associate the images or words with negative words.
Frost found that the subjects were slower at associating the details they had lied about with positive words than they were with negative words, which showed that subjects had a more difficult time viewing what they had lied about in a positive light. This confirmed Frost’s hypothesis that subjects do indeed harbor underlying negative attitudes toward lying, which in turn slows down thinking in
a measurable way.
Frost said he conducted this study in part because of the heightened interest in lie detection, particularly among law enforcement agencies.
“If the assumption that the results cannot be faked is confirmed by research, then perhaps the IAT could be used to corroborate a person’s legal case, assuming the judge finds the evidence admissible,” said Frost.Though Frost’s next step is to determine whether knowledge of the IAT or instructions to fake results could alter their findings, what he found has interesting and potentially important implications for criminal prosecution. In interviews, interrogations and confessions, subjects’ statements could be scrutinized under Frost’s expanded use of the IAT in order to determine their validity.
For example, if someone was suspected of a crime and had lied to police about his or her involvement, one might be able to tell that the suspect was lying based on his or her reaction times to images or words on a computer screen that were related to the crime, according to Frost.Frost is hopeful that even in the event that this test does not stand on its own as a determinant of someone’s honesty, at the very least it can complement the other tests already being used.
“It has been a challenge for researchers to create foolproof lie detection. My involvement in forensic research has been to fine-tune the procedures already in place and gain a better understanding of a liar’s thought processes. By doing so, we can better inform the courts and practices of law enforcement,” Frost said. “While I don’t believe we’ve found techniques that meet the rigor needed for conviction, perhaps a corroboration of our best techniques can help inform the courts about whether certain people should be considered for exoneration.”