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A research group headed by psychologist Prof. Dr. Bettina Pause from the Institute of Experimental Psychology, University of Düsseldorf, has proven that fear can be transmitted between two people via smell. It does not even have to be consciously perceived, proving that humans communicate chemically. Previous to this, such research was only known from the animal world.

The smell of somebody else's fear molecules activates the cerebral regions that are responsible for empathy and for recognising states of fear. These regions are the insular cortex, the cingulum and the fusiform cortex. Psychologists took samples of cold sweat from students just before they sat an important university exam. Subjects had to wear cotton pads under their arms for around 15 minutes before the exam. Sweat samples were also taken from the same subjects while they were working up a sweat on gym equipment.

These samples were processed and then presented to other subjects through an olfactometer, a device that delivers odour molecules at a constant temperature and flow rate. Subjects in the survey only perceived these odours very weakly. In fact, only half the subjects smelt the odour at all. The subject's brain activity was monitored by an MRI scanner during odour delivery. This highlighted those areas that are activated when subjects faced "fear". These areas handle emotional and social signals, are involved in the process of empathy and specialise in perceiving expressions of fear. By contrast, the presentation of sweat produced by doing sport failed to trigger any measurable responses.

Further information: www.psycho.uni-duesseldorf.de