IT has been observed in the past that somatic changes such as blister formation can be induced in hypnotized subjects by means of appropriate suggestion1,2. McDougall1 observed in several hypnotized subjects changes of surface temperature of 10° F (5.6° C) or more, produced after a few minutes of repeated suggestion of heat or coldness. It was thought, therefore, that skin temperature might rise following an illusory stimulus of heat in the heat illusion test2,3 with non-hypnotized subjects. Accordingly, the following experiment was carried out.