Contact with other sex makes us hot under the collar When the device was held against their palm, outer arm, chest or face, the women's facial temperature increased by an average of 0.1C. The change was much more pronounced when "personal" areas of the body, such as the face and chest, were touched and was stronger when the researcher was male rather than female. Amanda Hahn, who led the project, said: "The [temperature] change was driven by face and chest contact which were significantly higher than arm or palm contact. It is really the personal location contact that is causing it. A second experiment, with only male researchers carrying out the measurements, found that the temperature rise was strongest along the centre of the face, with increases of 0.2C around the nose, 0.3C around the eyes and 0.46C around the mouth. Miss Hahn said further studies would reveal whether similar social interaction also causes a change in the face's colour. She said: "We do not know at the moment whether temperature changes and colour changes are inherently linked but we would predict that if blood flow is increasing to an area, making it hot, it would also get redder." Facial redness has been shown in previous studies to make people appear more attractive, but it could also have a negative impact because blushing is a signal of feeling uncomfortable. Even if there is no change in colour the changes in facial temperature could still be detectable by others through touch or even smell, or they could be a signal to the individual themself to change their own behaviour, Miss Hahn added. She said: "Whether the changes measured in this study are detectable by others is currently unknown. If such changes in facial temperature during social contact are detectable by observers or the individual, they could act as social cues. Temperature changes may be evident to observers directly through touch, or indirectly through sight or smell. For example, because temperature changes are due to changes in blood flow, they may be visible via concurrent skin colour changes.