2012年4月28日 星期六

假如只有二十小時溫習……

二人學打字,資質相當,各自練習二十小時,你猜誰人比較純熟?

要貼士嗎?

貼士:阿甲每日練習二小時,連續十日;阿乙每年清明節練習五小時(以紀念教他打字的先人),連續四年。二十小時練習之後,你說甲純熟還是乙純熟?

對阿乙來說,去年苦練五小時的「成果」早已忘記得一乾二淨,每年清明節雙手放在鍵盤的感覺跟初學沒有兩樣。相反,阿甲每日練習,技術與日俱增,二十小時的效果比乙優勝。很明顯,甲的二十小時不同乙的二十小時。

想帶出的問題是,二十小時如何分配最有效?阿丙每日練習一小時,連續二十日,效果會否比阿甲更理想?阿丁隔日練習,每次二小時,共十天,效果又如何呢?這不單是學習打字遇到的問題,這是任何學生、教師、家長都應該思考的問題:某科目一個月之後考試,只能撥出二十小時溫習(因要兼顧其他功課),這二十小時應如何分佈呢?

我上網搜尋,希望從學術文獻找到一點啟示。首先找到的叫「total time hypothesis」,意即學習成效視乎溫習總時間(total time),換句話說,即是廢話。誰不知道花愈長時間溫習成績愈好?問題是如何運用有限時間最有效地溫習吧了。好奇心驅使,即管看看是哪些學者做了什麼實驗達到這個廢話結論。原來,概念在 1960 年代提出,實驗通常給受試者學習一系列無意義的符號,幾輪溫習之後,測試他們記得多少。溫習次數、每次溫習多久、溫習與溫習之間相隔多久都是可調較的,藉以觀察受試者在不同情況下的表現,結果發現成績高低的關鍵在於溫習總時間,即是說,溫習時間如何分配並不重要,最重要是累積時間。

Total time hypothesis 看似有實證支持,但魔鬼往往在細節之中。「學」一堆無意義的符號脫離現實不在話下,那些實驗是「超短期」的,每次溫習以秒計(三秒便溫習完畢?),溫習與溫習之間相隔以秒計(溫習完畢三秒之後再溫習?),溫習與測試的時差也是以秒計(考試之前三秒打開書本溫習一遍?),根本脫離現實。實驗通常是現實的簡化,有些實驗簡化至脫離了現實。

而且,total time hypothesis 根本有違常理,阿甲練習二十小時跟阿乙練習二十小時的效果差天共地,就是對 total time hypothesis 最大的反駁。

網上繼續尋找,終於找到一次較近期、較近乎視實的硏究。它的學習材料是一些鮮為人知的事實,例如雪地高爾夫(snow golf)由誰人發明(答案:Rudyard Kipling)、哪歐洲國家吃最多墨西哥食品(答案:挪威),全是一些真實的知識。受試者有兩次機會溫習,然後考試;變數有兩個:兩次溫習之間相隔的時間(0-105日不等)及第二次溫習與考試相隔的時間(7-350日不等);換句話說,第一次溫習之後,受試者可以即日重溫,也可以三個半月之後重溫;第二次溫習完畢,考試可以在一星期之後,也可以在大約一年之後。

結果發現,愈遲考試,兩次溫習最好隔得開一些。舉例,考試定在第二次溫習一星期之後,兩次溫習應該相隔多久?實驗說:「最好相隔一至兩天」。考試定在第二次溫習一年之後,兩次溫習應該相隔多久?常識說:「無乜所謂,反正一年後都是忘得一乾二淨」,但實驗說:「最好相隔三星期,這組受試者一年後成績最好」。沒有單一最佳相隔時段,要視乎考試定於何時。撇開考試,從長遠教育的角度,你希望學生七日之後記得書本的知識,還是一年之後依然不忘?如果着眼點在一年之後,功課和測驗的編排是否應該誘導學生溫習三星期前教過的東西?

我要向各位道歉,本文不能教你最佳的溫習模式,上述硏究雖然比較接近現實,但距離「求學只是求分數」的「香港現實」實在太遠。如果你想拿高分,便不應該把溫習上限定為二十小時(更不應只溫習兩次),應該把搭車、吃飯、玩樂、睡覺的時間也用來溫習。負責任的父母也不會讓你考試前一個月才作準備,他們會由懷着你的那天起,儲定幾百萬元,買定莫札特音樂,買定含豐富營養的奶粉給你作準備。

(2012 年 4 月 28 日 信報副刋)

學術參考:
Nicholas J. Cepeda, Edward Vul, Doug Rohrer, John T. Wixted, Harold Pashler (2008), “Spacing Effects in Learning: A Temporal Ridgeline of Optimal Retention,” Psychological Science, 19, 1095–1102. doi:10.1111/j.1467-9280.2008.02209.x

Nicholas J. Cepeda, Harold Pashler, Edward Vul, John T. Wixted, Doug Rohrer (2006), “Distributed practice in verbal recall tasks: A review and quantitative synthesis,” Psychological Bulletin, 132, 354–380. doi:10.1037/0033-2909.132.3.354

Elaine H. Cooper, Allan J. Pantle (1967), “The total-time hypothesis in verbal learning,” Psychological Bulletin, 68, 221–234. doi:10.1037/h0025052

4 則留言:

  1. How about learning by practice? For example, lean how to play a musical instrument? When I pick up an instrument, my teacher told me that if I had only 5 hours per week (between Monday to Friday), The most effective way is to practice 1 hour every day, instead of playing 5 hours continuously in one day. I believe it is true, as this is somewhat like developing a habit. What do you think? Can you find any study related to it?
    You blog is nice and interesting. I lean a lot. Thank you!
    Leo

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  2. 其實寫本文的時候,我想探究就是你提出的這種問題,例如練琴或操練某樣運動,每日練當然好,隔日練差一點,隔週差一點,每年練一次好像沒練一樣。臨界點在哪裡?隔多久練一次才好像沒練一樣?

    可是找不到滿意的答案,最近似就是 forgetting curve,顯示記憶如何隨時間 decay,不過它只說明單次記憶,多次記憶如何便無從稽考了。

    或許關乎 long term memory 的東西,我們還不太理解吧,又或者是我搜尋得不夠透徹,或用錯關鍵字吧。

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  3. I share with you my learning experience....When I was going to take the ABRSM exam. I practiced very hard, 4 hours per day at least. To a certain point of time, Mentally I was very tired. Tired of doing the same things. Then I stopped for few days or even a full week. Later I picked up the practice schedule again and felt refreshed. Also, the improvement is quite significant (as told by my teacher). So, as you said, how long should I stopped, so that I can get better and faster advancement on my skill?

    It seems there should be something more to be considered. However, I don't know what exactly it is...Or, my discussion is now out of topic?

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  4. Nothing is out of topic here.

    Yes, there are a lot of variables. How often you should practice? How long you should practice each time? What is the total time you should put in? Do these variables change with your skill level? There may be a simple answer, maybe not. I couldn't find anything definitive.

    I guess common sense is all we can rely on for the moment. We can't do something for 5 hours a day without getting tired or bored. Once we feel stuck, it's better to leave it and do something else. Doesn't take a lot of research to tell us that. We just have to listen to our heart and body.

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