Monday, April 6, 2009

What's the Matter With Lying?

The recent study on lying conducted by Dr. Adrian Raine and Yaling Yang at the University of Southern California is the first of its kind to prove a consistent structural abnormality in the brains of pathological liars. Using magnetic resonance imaging, Yang was able to measure a significant difference in the proportions of prefrontal white and gray matter among adults recruited from a temporary employment office in Los Angeles. Those who classified as ‘liars’ had much more white matter and slightly less gray matter in their prefrontal cortex than the members of both normal and antisocial control groups. According to their report, Yang and Raine's results, “Provide the first evidence of a structural brain deficit in liars, implicate the prefrontal cortex as an important (but not sole) component in the neural circuitry underlying lying and provide an initial neurobiological correlate of a deceitful personality.”



From their pool of volunteers Yang and Raine interviewed and tested participants and separated them into three groups: 12 adults whom they classified, according to certain criteria, as regular ‘liars;’ 21 normal, relatively honest adults; and 16 adults with antisocial personality disorder but no history of pathological lying. The liars targeted in the study were those with histories of manipulative and conning behavior and malingering (lying about ones health for personal gain). Yang and Raine then examined the volunteers’ brains using magnetic resonance imaging and found a considerable discrepancy between the grey/white matter ratios of the liars and of the two control groups. Liars showed 14 percent less gray matter in their prefrontal cortex than the normal individuals, but had 26 percent more white matter than the antisocial subjects and 22 more than the normal subjects. The Liars also exhibited a prefrontal gray/white matter that was much lower than both control groups.

1 Prefrontal grey and white matter volumes in liars ({blacksquare}), normal controls ({square}) and antisocial controls (&{graysqu}).

Prefrontal grey/white matter ratio in liars ({blacksquare}), normal controls ({square}) and antisocial controls ({graysqu}).


White Matter comprises 40-50% of the volume of a normal adult brain. It is a network made up of millions of axons that facilitate connections between the nerve cells (grey matter) in different parts of the brain. According to Dr. Sean A. Spence, Professor of Psychiatry at the University of Sheffeld, “White matter projections are especially abundant in the frontal lobes, consistent with the prefrontal executive role in modulating emergent behaviour via subordinate brain structures. Hence, white matter is pivotal to the connectivity and cognitive function of the human brain.” An excess of white matter would naturally correspond with the ability to links certain thoughts together in fabricating and fine-tuning a lie. Moreover, the liars in this particular study exhibited a slight deficit in grey matter in the prefrontal cortex which is where moral judgments, among other things, are processed. Consequently, as Raine put it, “They’ve got the equipment to lie, and they don’t have the disinhibition that the rest of us have in telling the big whoppers,”


Though this study focuses on just one part of the neural circuitry involved in lying, it raises many crucial questions about the potential of white matter connectivity, about the definition of “pathological lying” and different kinds of deceptions, about structural abnormalities as causes or affects of behavior, and about the relationship between neurological development and ones proclivity to lie.


"Radio Lab: Into the Brain of a Liar." Radio Lab. Narr. Robert Krulwich. National Public Radio.
6 March 2008

Spence, Sean A. "Prefrontal white matter -- the tissue of lies." The British Journal of Psychiatry. 187 2005: 326-327.

Yang, Yaling and Adrian Raine. "Prefrontal white matter in pathological liars."The British Journal of Psychiatry. 187 2005: 326-327.

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