There is an interesting communication by a group of psychiatrists from Massachusetts in Nature for May 11 regarding the ability of different people to detect a lie with which they are confronted. People suffering from aphasia, that is, the inability to understand words, were found to be significantly better at detecting lies about emotion than others with no language impairment. The suggestion was that loss of language skills may involve a superior ability to perceive the truth.
Ten patients were studied who could understand individual words but were severely deficient in comprehending spoken sentences on account of damage to their left cerebral hemisphere. Comparisons were made with 10 patients who had suffered damage to their right cerebral hemisphere, 10 healthy controls and 48 undergraduates from the Massachusetts Institute of Technology. The subjects viewed a film in which 10 people were shown, first trying to conceal powerful negative emotions and then honestly revealing positive emotions. The aphasics were significantly more accurate than the others at detecting lying emotions. Groups were then given clues involving facial expression, changes in voice pitch, and face and voice changes together. Clues involving facial expression had a greater effect on patients with left hemisphere damage.
It appears from these observations that aphasic individuals are unusually sensitive to behaviour calculated to deceive. This may represent compensatory development in recognising non-verbal stimuli, rendering aphasics superior to controls in the detection of facial expressions calculated to promote lies.