These discussions reveal the depth and difficulty of the problem. Here are some reasons why the issue is so difficult. At the physiological level, the afferent nerve channels that carry information about thermal properties are very similar to those that code for pain and itch, and they also differ significantly from those involved in the coding of pressure, shape, and vibration (for some empirical background, see Lumpkin and Caterina (2007); for important recent caveats, see Saal and Bensmaia (2014)). In other words, thermal channels are physiologically and functionally more similar to the nociceptive channels involved in pain than they are to the channels involved in discriminative touch (Schepers and Ringkamp 2010). And yet thermal awareness is often considered part of touch, indeed, it has often been thought of as one of the central aspects of touch. Pains, on the other hand, are almost never considered part of touch.