characterized lesions (Tranel and Damasio, 1994; Zahn, Grafman, and Tranel, 1999). The results of these studies underscore the complexity of the circuitry involved and also illustrate how the relationship between brain function and behavior can be understood in more detail when information on the former is directly available.

More immediately relevant to the use of fMRI for the detection of deception are the very few recent studies that use fMRI to identify associations between deception and specific brain activity. One recent study adapted the guilty knowledge test format for use with fMRI (Langleben et al., 2001). In 23 normal subjects, it was possible to detect localized activity changes in the brain that were uniquely associated with deception. Remarkably, these changes occurred in areas of the brain known to participate in situations involving response conflict (Miller and Cohen, 2001). In the study, the conflict involved overriding one (correct) response and providing a second (false or deceptive) response to a question.

Another study (Spence et al., 2001) used fMRI to study deception in an autobiographical memory task in which examinees were instructed to be truthful or to lie. The findings from this experiment indicated that during lying, compared with truthful responding, examinees exhibited significantly greater activation in the ventrolateral prefrontal cortex and the medial prefrontal cortex. Activation in several additional regions differentiated less strongly between the experimental conditions. In yet another recent study, Lee and colleagues (2002) instructed some subjects to feign a memory problem and deliberately do poorly on two memory tasks. One involved memorizing a three-digit number and reporting its correspondence with another number presented 2.25 seconds later; the other involved memory for the answers to such autobiographical questions such as “Where were you born?” The researchers reported differential patterns of activation that held across the two tasks when feigned memory impairment was compared with control conditions. The findings from this study revealed a distributed set of activations that included several regions of the prefrontal, parietal, and temporal cortices, the caudate nucleus, and the posterior cingulate gyrus.

The above studies suggest what might in principle be achieved by using a technique such as fMRI for the detection of deception. They also suggest the kinds of information needed in brain-based studies of detecting deception. These investigations seek to identify signatures of particular kinds of cognitive activity in brain processes. Yet even if fMRI studies could eventually identify signatures of acts of deception, it would be premature to conclude that fMRI techniques would be useful in practice for lie detection. Applied fMRI studies of the kinds done so far have similar limitations to those of typical laboratory polygraph research. They have limited external validity: the experimental lies were not high-stakes

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