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Lunchtime Talk at the Center for Philosophy of Science at the University of Pittsburgh (03/24/26), starts at 03:25 mins.

ABSTRACT: In 1896, the Swedish physiologist Torsten Thunberg reported a curious discovery: when he touched a grid of alternating warm and cold brass pipes, the sensations of warmth and cold on his hand somehow ‘fused together’ into a ‘special sensation of heat’ — a sensation that many experimental subjects since then have described as painful. Since the 1990s, this so-called ‘thermal grill illusion’ (TGI) has become the conventional method of investigating ‘illusory pain’, and is said to hold important insights for our understanding of the bodily senses and clinical pain pathologies. However, what exactly these insights are meant to be remains largely unclear: indeed, after more than a century of scientific interest in Thunberg’s discovery, the sensory fusion he described is about as puzzling as ever. In this talk, I aim to articulate why the thermal grill illusion is a puzzle worth caring about, why it has been so difficult to solve, and what, if anything, we can learn from putting our hand on a grill. 

 Appearance on Fun Kids Science Weekly's podcast episode 'Ouch: cracking the mystery of pain' (July 2025), starts at 17:35 mins