Figure 1.

Measurements of PHS. The standard and modified thermal sensory limen (TSL and mTSL) protocol. Participants pressed a button every time they registered a new sensation and reported whether it was warm or cold. A PHS was registered if the participant reported a warm sensation during cooling (a, b, c, d, e, and g) and a PCS was registered if the participant reported a cold sensation during warming (a, b, c, f, and h). a-c: The original thermal sensory limen (TSL) with alternating warming and cooling temperatures during three different situations: a: TSL measure from a healthy individual with normal thermal sensitivity. b: All button presses in the warm range, c: TSL measure from an individual with reduced thermal sensitivity. d-h: The modified thermal sensory limen (mTSL). Participants were told to press the button as soon as they felt a change in temperature after the auditory cue. d: mTSL with alternating warming and cooling temperatures similar to the TSL except for an auditory cue indicating when the temperature returned to baseline. e: mTSL with pre-warming and detection of temperature changes in the cold range and possible PHS. f: mTSL with pre-warming and detection of temperature changes in the warm range and possible PCS. g: mTSL with pre-cooling and detection of temperature changes in the cold range and possible PHS. h: mTSL with pre-cooling and detection of temperature changes in the warm range and possible PCS. For simplicity, only pre-warming of 44°C and pre-cooling of 20°C is presented. Blue lines: temperatures <32°C, dots: button presses and reported quality, horizontal line: baseline, Orange lines: temperatures >32°C, and rhombus: auditory cue.