Have you ever thought about why people are ticklish? According to scientists, ticklishness is a defense mechanism humans developed against bugs, spiders, and other critters that may be touching our skin. Feeling ticklish is our built-in response to predators or threats, and combines the sensations of touch and pain.

    The part of the brain that is associated with tickling is the cerebellum. It monitors our movements, but ignores movements not perceived as a threat. For example, we do not notice our vocal chords moving when we speak, but we may jump if someone touches us on the shoulder. This selective perception is probably the reason why we cannot tickle ourselves.

    We only feel ticklish if we detect a sense of invasion or attack. If we try to tickle ourselves, our brains anticipate this "attack" and prevent us from feeling panicked. Strangely enough, even if a person knows that they are about to be tickled, the fear of being touched may cause the same "ticklish" reaction. Some people laugh even before being tickled.
   
    A scientific study was recently done in England to determine whether or not people can tickle themselves. Volunteers were attached to a brain-scanning device and were tickled on their palms with a piece of soft foam . The participants' brain scans were monitored while they were being tickled, and when they tickled themselves. It was found that during self-tickling, the cerebellum alerted another area of the brain about what to expect, so the ticklish feeling was diminished.
 
    Researchers did find a way, however, for people to tickle themselves. When volunteers activated a robot by remote control to tickle them after a short delay, the volunteers felt as if someone else were tickling them. It seems that the cerebellum sends a signal to disregard the forthcoming movement, then moves on to other things. Your brain "forgets" that you are tickling yourself—even with a delay as short as a fifth of a second. So it is possible to tickle yourself—but only by remote control. What will science discover next? 

    你有沒有想過人為什麼會怕癢？根據科學家的觀點
，怕癢是一種防禦機製，是人類把它培養來對付那些可能接觸我們皮膚的蟲子、蜘蛛或其他生物。怕癢是我們對侵擾者或威脅產生的內在反應，它使觸覺和痛覺結合起來了。

    naobuyupayangyouguandebuweishixiaonao。xiaonaojiankongwomendeyijuyidong，danduiqirenweibujuweixiexingdehuodong，wangwanghuihushi。julilaishuo，womenshuohuashibuhuichajiaoshengdaidezhendong
，danshiruyourenchumowomendejianpangshi，womenkenenghuixiayitiao。zhezhongxuanzexingdezhijiaohuoxujiushiwomenwufaziyihayangdeyuanyin。

    我們隻會在察覺受到侵犯或攻擊時才會覺得癢。如果試著替自己哈癢，腦部會自動預感到這種“攻擊”從而使我們感覺不到驚嚇。奇怪的是，即使有人知道他要被哈癢了
，擔心被人觸摸，也會引起同樣“怕癢”的反應。有些人甚至還沒被哈到癢就先笑了。

    英ying格ge蘭lan近jin期qi做zuo了le一yi項xiang關guan於yu人ren是shi否fou可ke以yi替ti自zi己ji哈ha癢yang的de科ke學xue研yan究jiu。自zi願yuan受shou測ce者zhe接jie上shang腦nao部bu掃sao描miao儀yi，並bing用yong一yi塊kuai軟ruan泡pao沫mo綿mian給gei手shou掌zhang哈ha癢yang。參can與yu者zhe在zai被bei哈ha癢yang和he自zi行xing哈ha癢yang時shi，腦nao部bu掃sao描miao狀zhuang況kuang都dou受shou到dao監jian視shi。結jie果guo發fa現xian
，在zai自zi行xing哈ha癢yang的de過guo程cheng中zhong，小xiao腦nao會hui向xiang腦nao部bu的de另ling一yi部bu位wei發fa出chu警jing告gao，使shi其qi預yu先xian防fang範fan，所suo以yi癢yang的de感gan覺jiao就jiu消xiao失shi了le。

    然ran而er，研yan究jiu人ren員yuan也ye發fa現xian了le可ke以yi替ti自zi己ji哈ha癢yang的de方fang法fa。自zi願yuan者zhe用yong遙yao控kong器qi操cao縱zong機ji器qi人ren，延yan遲chi片pian刻ke之zhi後hou再zai讓rang機ji器qi人ren為wei自zi己ji哈ha癢yang
，自zi願yuan者zhe就jiu會hui覺jiao得de好hao像xiang是shi別bie人ren在zai給gei他ta們men哈ha癢yang。看kan來lai小xiao腦nao在zai發fa出chu信xin號hao忽hu視shi即ji將jiang到dao來lai的de動dong作zuo，然ran後hou將jiang注zhu意yi力li轉zhuan移yi到dao其qi他ta事shi物wu上shang。盡jin管guan隻zhi有you零ling點dian二er秒miao的de時shi間jian差cha，腦nao部bu就jiu會hui“忘記”你在替自己哈癢。所以自己給自己哈癢仍有可能
，隻不過需要依靠遙控器。誰知道接下來科學還會有什麼新發現呢？