As decidedly underscored by a recent editorial in Nature Neuroscience (2010), many experiments
in cognitive neuroscience have been carried out with a sample that is not representative of the general human
population, as the subjects are usually university students in psychology. The underlying assumption of this
practice is that the workings of the brain do not vary much even when subjects come from different cultural
groups. Recent research by Henrich et al. (2010) shows that this assumption is unwarranted. On several
basic features of perception and cognition, Western university students turn out to be outliers relative to the
general human population, so that data based on them should be interpreted with caution. In particular, this
situation seems to provide an argument for questioning the conformity of functional Magnetic Resonance
Imaging (fMRI) lie-detection to Federal Rule of Evidence 702 and Daubert. Deception is a social
phenomenon and it is related to mental functions, such as theory of mind, for which cross-cultural variability
at the neural level has been detected. Furthermore, culture is a multi-dimensional variable whose effects are
diverse. Thus, the use of fMRI lie-detection in legal contexts may hinder the ascertainment of truth if the
experimental results are not shown to be conserved in different cultures. Cross-cultural variability in
neural activation patterns is just a facet of the broader issue of external and ecological validity for
neuroscientific experiments on the detection of deception; nonetheless, fMRI lie- detection is unlikely
to meet the Daubert standards if cross-cultural variation is not controlled by appropriate experiments
