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The threshold of pain or pain threshold is the point along a curve of increasing perception of a stimulus at which pain begins to be felt. It is an entirely subjective phenomenon. A distinction must be maintained between the stimulus (an external thing that can be directly measured, such as with a thermometer) and the person or animal's resulting pain perception (an internal, subjective thing that can sometimes be measured indirectly, such as with a visual analog scale). Although an IASP document defines "pain threshold" as "the minimum intensity of a stimulus that is perceived as painful", it then goes on to say (contradictorily in letter although not in spirit) that:〔
Although the phrasing may not convey it perfectly, and although this article itself is somewhat incoherent, the distinction clearly meant is the aforementioned one between the stimulus and the perception of it. The intensity at which a stimulus (e.g., heat, pressure) begins to evoke pain is thus called by a separate term, ''threshold intensity''.〔 So, if a hotplate on a person's skin begins to hurt at 42°C (107°F), then that is the ''pain threshold temperature'' for that bit of skin at that time. Forty-two degrees Celsius is not the pain threshold (which is internal/subjective), it is the temperature at which the pain threshold was crossed (which is external/objective). Of course, that leaves one to wonder exactly what "pain" means as an objective measure when there is no corresponding subjective experience of pain. The intensity at which a stimulus begins to evoke pain varies from individual to individual and for a given individual over time. ==Heat== The temperature at which heat becomes painful for a recipient is the ''heat pain threshold'' for that person at that time. One study showed that morning oriented people have higher pain threshold for heat as compared to evening oriented individuals 〔(Jankowski, K.S. (2014). Morning types are less sensitive to pain than evening types all day long. ''European Journal of Pain, 17,'' 1068–1073. )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「threshold of pain」の詳細全文を読む スポンサード リンク
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