A Nose For Evil

The results of new study suggest that psychopaths can't pass a smell test:

The researchers found that those individuals who scored highly on psychopathic traits were more likely to struggle to both identify smells and tell the difference between smells, even though they knew they were smelling something. These results show that brain areas controlling olfactory processes are less efficient in individuals with psychopathic tendencies. 

Poor smelling is thought to correlate with psychopathic traits because the orbito-frontal cortex both processes smells and regulates impulse-control and the observing of social rules. The potential implications for this particular study:

The finding could be useful for identifying psychopaths, who are famously manipulative in the face of questioning, says the paper, published in the journal Chemosensory Perception. “Olfactory measures represent a potentially interesting marker for psychopathic traits, because performance expectancies are unclear in odour tests and may therefore be less susceptible to attempts to fake ‘good’ or ‘bad’ responses.”