Vilayanur S. Ramachandran of the University of California at San Diego and his colleagues tested four patients who had experienced damage to the left angular gyrus region of their brains. All of the volunteers were fluent in English and otherwise intelligent, mentally lucid and able to engage in normal conversations. But when the researchers presented them with common proverbs and metaphors such as "the grass is always greener on the other side" and "reaching for the stars," the subjects interpreted the sayings literally almost all of the time. After being pressed by the interviewers to provide deeper meaning, "the patients often came up with elaborate, even ingenious interpretations, that were completely off the mark," Ramachandran remarks. For example, patient SJ expounded on "all that glitters is not gold" by noting that you should be careful when buying jewelry because the sellers could rob you of your money.
The angular gyrus is more developed in humans than in other primates and is located in the brain at the junction of areas specialized for processing touch, hearing and vision. "While it would be premature to conclude that the angular gyrus is the 'metaphor center' of the human brain," Ramachandran says, "we suggest that the evolution of the dominant angular gyrus contributed enormously to the evolution of many quintessentially human abilities, including metaphorical--and other abstract--thinking." He will present the results on Friday at the annual meeting of the American Psychological Society in Los Angeles.