The hot water test is actually one of the nicer tests.<p>120 F isn&#x27;t that hot, it only hurts after a while, and the mouse can take its tail out at any time. That&#x27;s how they were able to detect the effect; the mice that saw the other mice do the test took their tails out faster because they knew it&#x27;d eventually hurt based on the prior mouse&#x27;s reaction.