Mechanism of pressure sensation generated by hot steam

When a hand is held above boiling water, a sensation of pressure is sometimes experienced in addition to the expected thermal sensation. The underlying cause of this phenomenon is currently unclear. Potential candidates for the causal mechanism of this experience include steam, temperature, humidity and tactile receptor activity. In this paper we investigated the underlying mechanism of this novel non-contact tactile experience. To this end, we tested separate aspects of this experience independently. Our results suggest that stimulation of Merkel cells via sweat duct expansion is the principal cause this perceptual phenomenon.