The water vaporises, creating a barrier of steam between the hot and cold objects. Hence the two objects do not actually touch and evaporation from the cold object is much slower than might otherwise be expected. Since steam is a relatively poor conductor of heat the foot does not get burned. Other scientists believe that the Leidenfrost effect is unimportant in firewalking. Pain perception is not as simple as everyday experience suggests.
Some people experience great pain without any apparent cause.
Others experience little or no pain despite great injury. Cognitive and emotional factors seem to be important. A belief that one has control over the pain seems to reduce the level of pain experienced. Fear seems to increase it. Firewalking is usually done in a religious or spiritual context.