Why Does Very Hot Water Sometimes Feel Cold?

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Cold receptors primarily react to temperatures ranging from 68 to 86˚F, while warm receptors are activated between 86˚F and 104˚F. At extreme temperatures—below 60˚F and beyond 113˚F—the temperature signal is accompanied by a sensation of pain. Weirdly, researchers have discovered that at temperatures greater than 113˚F, some cold receptors can also fire.

The majority of scientists support the theory that paradoxical cold is a malfunction of the thermoreceptor system. Evidence suggests that pain receptors that respond to potentially harmful heat levels coexist on the same sensory fibers as cold thermoreceptors, says Lynette Jones, a senior research scientist at MIT. So when the nerve fiber sends a signal to the brain, it can sometimes be misinterpreted as a sensation of extreme cold. Paradoxical cold is the “strange operation of a system under unusual stimulation conditions,” she says… Read more

How to demonstrate sentience?

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In this short piece, Manu Herrán sumarizes two sets of proposals to address the problem of sentience, three mechanisms to show if an individual feels (the resemblance, the best possible explanation and Phenomenal Puzzles) and two ways to check if a theory of sentience is correct or not.

“It is common to ask: how can sentience (the ability to feel) be demonstrated? The question has several interpretations and nuances. On the one hand, whoever asks this question may be pointing out the difficulty of making predictions and obtaining evidence; In short, the difficulty of using the scientific method in the matter of sentience. But, as this article explains, there are many things we can do to address the issue of sentience in the most scientific way possible.

The question can also refer to a specific individual: how to know if an individual feels or not ?; Or it can refer to theories about sentience: what is the correct theory? How can we prove it?”

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