Do you think you’re an extravert or anintrovert? To answer, you might immediately ponder how much you like going toparties and talking to strangers, or perhaps you’ve already got an answer givento you by one of those online quizzes that prompt such self-reflection. The troublewith these approaches of course is that they rely on honest insight and a heftydose of subjectivity². Maybe you quite like parties, for instance, but nowherenear as much your best friend –does that make you an extravert or not?

你认为你是外向还是内向的人？要回答这个问题，你或许会马上想到自己是否热衷于去派对和与陌生人聊天，或者你已经从那些自我评估的在线心理测试中得到了答案。这些方法的问题在于它们依赖于诚实的自省和大量的主观动因。也许你也很喜欢聚会，但是程度远不及你的闺蜜，那么你到底是不是外向型人格呢？

A completely different approach that getsround these problems involves using a lemon – more specifically, concentratedlemon juice. This is a test with a long history in personality psychology³ andit’s really easy to try out at home. You’ll need a cotton bud (or what’s calleda cotton swab or Q-tip in the US) with a short piece of thread tied exactly inthe middle of it. Now place one end of the cotton bud on your tongue for 20seconds. Next, put five drops of concentrated lemon juice onto your tongue,swallow, and then put the other end of the cotton bud onto your tongue for 20seconds. Finally, take the end of the cotton bud out of your mouth and hold thecotton bud dangling⁴ by the thread. The idea is to see whether it hangshorizontally, or whether the end that you used after the lemon juice hangslower because it is heavier.

使用柠檬，更具体的说是使用柠檬汁，来进行测试是一种完全不同的测试方法，或许可以绕过这些问题。这是一个具有悠久历史的人格心理学测试，在家里很容易尝试。你需要一个棉签（棉花棒），中间系一根短线。现在把棉签的一段放在舌头上保持20秒，下一步，滴5滴浓缩柠檬汁在你的舌头上，做吞咽动作，然后把棉签的另一端放在你的舌头上保持20秒。最后，把棉签从嘴里拿出来，用线拎起来并看棉签是否能够保持水平，或者在吞咽柠檬汁之后放入的一端由于重量加重而更低一些。

If your reaction to the lemon juice madeone end heavier this suggests that the juice caused you to salivate more thannormal, which is a sign that – at a physiological⁶ level – you are an introvert¹.If the cotton bud is horizontal, this suggests you didn’t react much to thelemon juice and that you are probably an extravert.

如果测试结果显示其中一端更重，那么这意味着柠檬汁使你分泌了更多的唾液，从生理学上，这样的现象可以解读为你是内向型人格，如果棉签保持水平，那么这说明你对柠檬汁反应不强烈，你可能是个外向的人。

How come? This is a version of a testdescribed way back in the 1960s by one of the pioneers of personalitypsychology, Hans Eysenck, and his wife and fellow personality researcher SybilEysenck. In the original experiment, they used sensitive weighing equipment tomeasure how much saliva⁵ was absorbed into a cotton bud before and after people wereexposed to the juice. (The simplified DIY version described here comes from thecontemporary personality expert Brian Little in his 2014 book Me, Myself andUs.)

原因呢？这个测试早在上世纪60年代由人格心理学先驱，汉斯·艾森克（Hans Eysenck），和他的妻子，同为人格学研究员的西比尔·艾森克（Sybil Eysenck）共同发明。在最初的实验中，他们使用了精密的称重装置来测量人们接触到果汁前后，吸收到棉签里的唾液量。（这里描述的简化DIY版本来自当代人格专家布瑞恩·力拓（Brian Little）2014一书《我，我自己和我们》（Me, Myself and Us）。

The Eysencks wanted to test Hans Eysenck’sown “cortical arousal” theory of extraversion and introversion⁷. He proposedthat this aspect of personality has a physiological basis and that introvertshave higher baseline cortical arousal, which makes them react more strongly tostimulation; essentially⁸, they feel things more intensely, perhaps causing themto shy away from certain situations. The Eysencks claimed that the lemon testsupported the theory because people who score higher on questionnaire measuresof introversion tend to salivate more in response to lemon juice.

艾森克夫妇当时在测试汉斯艾森克独创的有关外向性与内向性的“大脑皮层兴奋”理论。他提出人格学的这个方面可以从生理学上找到原因，内向的人有更高的大脑皮质兴奋的水准，使他们对感官刺激反应更为强烈；从本质上讲，内向型人感情强烈，会主动远离某些情况。艾森克夫妇声称柠檬测试支持了他们的理论，因为在内向型性格测试问卷中，那些得高分的人往往会在柠檬测试中分泌更多的唾液。