A cognitive neurobiological account of deception: Evidence from functional neuroimaging van Spence et. al. (2004) - artikel

Innocent deception, like white lies or telling harmless lies, is considered to be normal. Telling lies is supposed to be socially undesirable, but living in total truthfulness is almost impossible. Indeed, total truthfulness and with that an inability to deceive is associated with neurological disorders like autism.

There are two psychological mechanisms involved in the ability to lie. The theory of mind, the ability to infer what others think, is one of them. The ability to lie is dependent upon the liar’s recognition that his thoughts are not known to others, and that different individuals’ understanding of the world may differ. The other mechanism involved is deontic reasoning: the appreciation of social rules and the consequences of their transgression. Therefore, liars almost always receive some advantages by their deceptive behavior.

When humans lie, they probably use some of the highest brain centres they have, since it is adaptive behavior in difficult circumstances. This is a proposition that has implications for notions of moral responsibility. Control functions, also called executive functions, include planning, problem solving, initiation and inhibition of behavior and the manipulation of useful data in conscious working memory. The executive functions mainly take place in the regions of the prefrontal cortex. The difficulty of deceiving lies in what’s at stake. In high stake situations, when information must be recalled, emotions and behaviors most be controlled and information must be managed, deception is hard. Managing information is part of the executive tasks. If a liar gets distracted, he might mistakenly tell the truth.

The motor behaviors of liars may also give away the fact they’re deceiving: while telling complex lies, fewer hand and arm movements are made. The motivational impairment effect means the slowing of behavior exhibited by liars.

The cognitive process of lying

When someone’s lying, a new item of information must be constructed, while withholding the truth (a factual item). Therefore, we might propose that responding with a lie demands some form of additional cognitive processing. This would take place in the executive, prefrontal systems (more than telling the truth). This hypothesis was tested using neuroimaging.

Ford stated that lesions in the orbitofrontal cortex led to tactless behavior. It is therefore hypothesized that the presence of an intact orbitofrontal cortex facilitates telling lies by being able to inhibit telling the truth.

Spence proposed that inhibition of telling the truth is associated with greater activity of ventral prefrontal regions. Lying would be associated with greater dorsolateral prefrontal cortical activity. This was tested using the brain imaging technique fMRI. The data supported the hypothesis that there was more activation when telling a lie, and that telling a lie took longer than telling the truth. However, the increased activation was found in the bilateral ventrolateral prefrontal and anterior cingulate cortices. Therefore the predictions about which regions would be more activated were only partly confirmed.

Lee used behavioral experiments in which he studied healthy participants feigning memory impairment. He suggested that malingerers would mind their response performance during the examination, so they wouldn’t perform too badly which would raise suspicion. Using an MR scanner, malingering was associated with increased activation in bilateral dorsolateral prefrontal, inferior parietal, middle temporal and posterior cingulate cortices, together with bilateral caudate nuclei.

Ganis made a distinction between rehearsed and spontaneous lies. He found greater right frontal activation in rehearsed lying. Spontaneous lying was associated with greater anterior cingulate cortex and visual cortex activity.

The current studies are limited by a certain level of artificiality, and ‘low stake’ lying situations. Therefore, in further research, experimenters should look for other paradigms for testing neurological components of deception. A promising cognitive subtraction that would reveal the brain regions involved with lying (rather than by memory) is the following:
(lie-truth) – (defy-comply) = brain activations specific to lying.

There have been no studies published who used fMRI and found increased activation in any brain region during truthful responding.