According to thermal research at the University of Granada’s Department of Experimental Psychology, there is an increase in the temperature at the top of the nose, near the eye, when someone is lying.
In pioneering research, the department has linked some psychological states to temperature rises and falls in different parts of the body. Although a link has been known between emotional states and some temperature changes in the body, the research has found more specific relationships.
Scientists have discovered that when a mental effort is made (performing difficult tasks, being interrogated on a specific event or lying) face temperature changes.
According to the article in Science Daily ‘When we lie about our feelings, the temperature around our nose raises and a brain element called “insula” is activated. The insula is a component of the brain reward system, and it only activates when we experience real feelings (called “qualias”). The insula is involved in the detection and regulation of body temperature. Therefore, there is a strong negative correlation between insula activity and temperature increase: the more active the insule (the greater the feeling) the lower the temperature change, and vice versa, the researchers state.’
You can read the full article on the Science Daily website.