This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
2006 First Web Paper
Shakespeare once said "Oh, what a tangled web we weave / When first we practice to deceive", but it is doubtful that he understood how this relates to neurobiology. A lie can begin a chain of reactions that can wraps up an entire society, but what kind of tangled web exists in the mind of the liar? If we assert that the brain equals behavior, there must be something about lying that changes in the brain because it is not an automatic behavior. Where is there brain activity for lying, and why should the government take notice?
There are different types of lies that we are capable of expressing. One of the more subtle types are lies of omission For example, you meet your best friend and her sister for lunch, and you can't help but notice that her sister has a very strange habit that annoys you. When you talk about the lunch later but don't mention her sister's annoying habit, you're omitting an important piece of the puzzle, and that is considered a lie. A lie of commission is the daily placating statement of "Just what I needed!" when you receive a useless present, or the automatic "Fine" response to "How are you?" These everyday lies generally aren't malicious enough to merit a polygraph test, and leaves the question of whether or not these statements look the same in the brain as lies that threaten a marriage or National Security. (1)
Myths that surround lies mostly concern the definition of a "liar". It is assumed that when a person lies, there is a physiological change in their demeanor. Specifically, a liar may squirm, sweat, or fidget. Strangely there are assumptions of just the opposite – that a liar will hold very still and make direct eye contact. Everyday we lie, and we do it well, whether we lie to a jury of our peers or simply tell a friend that their hair looks nice when we think the contrary. If we started to sweat and fidget every time we faked a compliment, our relationships would quickly be sabotaged. (1)
This is the reason why the polygraph machine method of lie detection is so inaccurate and outdated. The polygraph's purpose is to measure the physiological characteristics that come with lying, as previously mentioned. According to the American Polygraph Association, they test the sweat glands and cardiovascular activity of the subject, but deny that voice stress testing is accurate. (2)
However there have been various neurological tests using a functional-MRI scanner that are simply better. Lying requires a change in behavior, and therefore the brain as well. Assumed signs of a liar can be easily trained away, especially in cases of important secrets regarding National Security. Very few people can identify a liar just based on sight, and the polygraph machine would identify extreme anxiety as lying. (1)
One of these experiments using functional-MRIs is conceived by Daniel Langleben of the University of Pennsylvania. The scan measures how much oxygen is being used in the brain and this information can be plotted, in essence, on an anatomical brain map to demonstrate what part of the brain is activated during a particular task. The experiment requires participants to holds a playing card in their pockets, specifically the five of clubs, while answering yes-no questions about which card they are holding. A screen shows pictures of playing cards and the subject selects "yes" if they have it and "no" if they do not. When the five of clubs is shown, they are required to answer "no", which is a lie. Langleben admits that this doesn't provide a map of where deception takes place, but it does suggest an increase of activity in places like the anterior cingulate cortex and the superior frontal gyrus. Additionally, the prefrontal cortex has an increase in activity, which is the reasoning part of the brain. (3)
With some revisions to his experiment, Langleben notices some activity in the parietal cortex, which is activated during physical stress changes like goosebumps and sweating. This connection to sweating may indicate a link to the polygraph, but it is purely coincidental. The inventors of the polygraph didn't intend that someday this connection would be made, but it gives us some hope for the machine. After all, there's a chance that the first-time criminals and liars that police departments are trying to catch will react to the polygraph. But the functional-MRIs take place in an environment so unnatural that it is only worthy of detecting secrets of national security, or proving the innocence of a death-row inmate. (1)
One other method of lie detection used in the wake of September 11th is called "brain fingerprinting". These tests are EEG-based, and measures the information stored in our brains. It functions by showing a list of words to a person, and then recognized words show a different neural pattern than new ones. This makes the assumption that we store guilty knowledge in our brain. It's not the same as detecting deception, but it may be even more useful to the government in its counterterrorism efforts – that is, if they can get cooperation. As mentioned above, these studies take place in such an unnatural setting that other thoughts could take over the brain. The anxiety associated with interrogation decreases polygraph efficiency, and we can't expect much better results with these tests. But in the spirit of the scientific method, there's no reason to stop trying. (4)
Locating where deception takes place should spark interest in the government's counterterrorism and justice efforts. If you're an innocent citizen waiting for execution or wrongly accused at the airport, it's unlikely that even in strange conditions you will lie. However, it leaves us with even more questions, specifically about truth. Obviously these tests are showing a more complex process for lying, but there are some questions that have no set truth, but rather an individual belief – do these beliefs require activation of less neurons than telling the truth or lying? We may never know answers to our questions that cross philosophy with physiology because the search for lies is so invasive among people who value privacy and free will.
1) Henig, Robin Marantz. "Looking for the Lie". 05 February 2006. New York Times. http://www.nytimes.com/2006/02/05/magazine/05lying.html.
Note: article now only available to New York Times subscribers.
2)2> http://www.polygraph.org/faq.htm">http://www.polygraph.org/faq.htm The American Polygraph Association FAQ, on the American Polygraph Association official website
3) Tran, Trinh. "Truth and deception— the brain tells all". 11 April 2002. The Penn Current. http://www.upenn.edu/pennnews/current/2002/041102/research.html.
4) Moenssens, Andre. "'Brain Fingerprinting' – Is It A Reliable Tool?". 02 July 2000. Forensic-Evidence.com. http://www.forensic-evidence.com/site/Behv_Evid/BeE00005_1.html.
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