總是考滿分可能學不到新東西! 研究指出學習的最佳「甜蜜點」應為85分

鐘承諭 | 2019年11月05日

為了學習新知,我們有時必須經歷一些挫敗,但多少失敗才是最有效的呢?美國亞利桑納大學一份研究給出了一個數字。根據這項發表於《Nature Communications》期刊的新研究指出,當有15%的時間碰到挫折會是最有效的,換句話說,就是當正確率達到85%時,學習效果最佳。

To learn new things, we must sometimes fail. But what's the right amount of failure? New research led by the University of Arizona proposes a mathematical answer to that question. According to the new study, to be published in the journalNature Communications, it's when failure occurs 15% of the time. Put another way, it's when the right answer is given 85% of the time.


We learn best when we are challenged to grasp something just outside the bounds of our existing knowledge. When a challenge is too simple, we don't learn anything new; likewise, we don't enhance our knowledge when a challenge is so difficult that we fail entirely or give up.



The so-called "85% Rule" after conducting a series of machine-learning experiments in which they taught computers simple tasks, such as classifying different patterns into one of two categories or classifying photographs of handwritten digits as odd versus even numbers, or low versus high numbers. The computers learned fastest in situations in which the difficulty was such that they responded with 85% accuracy.


當我們思考人類如何學習時,「85法則」應會較適用於根據經驗與案例逐步學習的感知學習(perceptual learning)方式,例如一位放射科醫生(radiologist)學習如何從圖片分辨腫瘤與非腫瘤。

When we think about how humans learn, the 85% Rule would mostly likely apply to perceptual learning, in which we gradually learn through experience and examples, Imagine, for instance, a radiologist learning to tell the difference between images of tumors and non-tumors.


「你會隨著時間越來越會分辨圖片中的腫瘤,而你需要經驗與案例來促進學習」,這項研究的主持人Robert Wilson表示,「我能想像給出簡單、困難與中等案例的情形,如果我給的是太簡單的案例,而你每次都能夠達到100%正確率,那就沒有什麼學習空間;如果我給你太難的案例,你會得到50%的正確率,但你還是沒學會任何新東西;但是如果我給你介於兩者之間的(案例),你就能夠從每個特定案例中得到更多資訊,達到最佳的學習點。」


"You get better at figuring out there's a tumor in an image over time, and you need experience and you need examples to get better," Wilson said. "I can imagine giving easy examples and giving difficult examples and giving intermediate examples. If I give really easy examples, you get 100% right all the time and there's nothing left to learn. If I give really hard examples, you'll be 50% correct and still not learning anything new, whereas if I give you something in between, you can be at this sweet spot where you are getting the most information from each particular example."



Since Wilson and his collaborators were looking only at simple tasks in which there was a clear correct and incorrect answer, Wilson won't go so far as to say that students should aim for a B average in school. However, he does think there might be some lessons for education that are worth further exploration. "If you are taking classes that are too easy and acing them all the time, then you probably aren't getting as much out of a class as someone who's struggling but managing to keep up".