When we think about learning, we often picture students in a classroom or lecture hall, books open on their desks, listening intently to a teacher or professor in the front of the room. But in psychology, learning means something else. To psychologists, learning is a long-term change in behavior that's based on experience. Two of the main types of learning are called classical conditioning and operant, or instrumental, conditioning. Let's talk about classical conditioning first. In the 1890's, a Russian physiologist named Ivan Pavlov did some really famous experiments on dogs. He showed dogs some food and rang a bell at the same time. After a while, the dogs would associate the bell with the food. They would learn that when they heard the bell, they would get fed. Eventually, just ringing the bell made the dogs salivate. They learned to expect food at the sound of a bell. You see, under normal conditions, the sight and smell of food causes a dog to salivate. We call the food an unconditioned stimulus, and we call salivation the unconditioned response. Nobody trains a dog to salivate over some steak. However, when we pair an unconditioned stimulus like food with something that was previously neutral, like the sound of a bell, that neutral stimulus becomes a conditioned stimulus. And so classical conditioning was discovered. We see how this works with animals, but how does it work with humans? In exactly the same way. Let's say that one day you go to the doctor to get a shot. She says, "Don't worry, this won't hurt a bit," and then gives you the most painful shot you've ever had. A few weeks later you go to the dentist for a check-up. He starts to put a mirror in your mouth to examine your teeth, and he says, "Don't worry, this won't hurt a bit." Even though you know the mirror won't hurt, you jump out of the chair and run, screaming from the room. When you went to get a shot, the words, "This won't hurt a bit," became a conditioned stimulus when they were paired with pain of the shot, the unconditioned stimulus, which was followed by your conditioned response of getting the heck out of there. Classical conditioning in action. Operant conditioning explains how consequences lead to changes in voluntary behavior. So how does operant conditioning work? There are two main components in operant conditioning: reinforcement and punishment. Reinforcers make it more likely that you'll do something again, while punishers make it less likely. Reinforcement and punishment can be positive or negative, but this doesn't mean good and bad. Positive means the addition of a stimulus, like getting dessert after you finish your veggies, and negative means the removal of a stimulus, like getting a night of no homework because you did well on an exam. Let's look at an example of operant conditioning. After eating dinner with your family, you clear the table and wash the dishes. When you're done, your mom gives you a big hug and says, "Thank you for helping me." In this situation, your mom's response is positive reinforcement if it makes you more likely to repeat the operant response, which is to clear the table and wash the dishes. Operant conditioning is everywhere in our daily lives. There aren't many things we do that haven't been influenced at some point by operant conditioning. We even see operant conditioning in some extraordinary situations. One group of scientists showed the power of operant conditioning by teaching pigeons to be art connoisseurs. Using food as a positive reinforcer, scientists have taught pigeons to select paintings by Monet over those by Picasso. When showed works of other artists, scientists observed stimulus generalization as the pigeons chose the Impressionists over the Cubists. Maybe next they'll condition the pigeons to paint their own masterpieces.
說到學習,我們通常會想到 學生坐在教室或講堂裡, 桌上是打開的書本,認真 聽著前面的老師或教授講課。 但在心理學中,學習有不同的意義。 對心理學家而言,學習是根據經驗 所造成行為上的長期改變。 兩種主要的學習類型是古典制約 以及操作制約,或稱工具性制約。 咱們先來談古典制約。 1890 年代, 俄國生理學家伊凡巴夫洛夫 對狗進行了一項知名的實驗。 他把食物給狗的同時也會搖鈴。 一段時間後,狗就會 把鈴聲和食物連結起來, 進而學到:聽到鈴聲時就有東西吃。 最後,單是搖鈴就會讓狗流口水。 牠們聽到鈴聲時就預期會有食物。 在正常狀況下, 看見和聞到食物會讓狗流口水。 我們把食物稱為非制約刺激, 把流口水稱為非制約反應。 狗不用訓練就會對著牛排流口水。 然而,當我們把非制約刺激 ——即實驗中的食物—— 和原本中性的東西 ——即實驗中的鈴聲—— 配對起來, 該中性刺激就會變成制約刺激。 於是,他發現了古典制約。 我們能了解動物的古典制約, 但在人類身上會是什麼樣子? 完全一樣。 比如,有天你去找醫生幫你打針, 她說:「別擔心,一點也不會痛。」 接著幫你打了你這輩子最痛的一針。 幾週後,你去牙科檢查牙齒。 他把鏡子伸進你的嘴裡 以查看你的牙齒, 他說:「別擔心,一點也不會痛。」 即使你知道鏡子不會讓你痛, 你還是從椅子上跳起來, 尖叫著衝出診間。 你先前去打針時, 「一點也不會痛」這句話 和打針痛感的非制約刺激配對結合, 變成了制約刺激。 接續的是你的制約反應 「快離開那裡」。 這就是古典制約在運作。 操作制約能說明行為的後果 如何導致自願性的行為改變。 那操作制約又是怎麼回事? 操作制約有兩個主要元素: 增強和懲罰。 增強物會讓你再做 同一件事的可能性增加, 懲罰物則相反。 增強和懲罰都有正面和負面兩種, 但不等同於好與壞。 正面表示增加刺激, 比如吃完蔬菜就可以得到甜點, 負面表示拿掉刺激, 比如考試成績良好就有一天 不用寫回家功課。 咱們來看看操作制約的例子。 和家人共進晚餐之後, 你整理了餐桌也洗了碗盤。 做完之後,母親給你一個大擁抱, 說:「謝謝你幫我。」 在這個情況中, 母親的反應就是正面的增強, 因為她的反應讓你更有可能 重覆你的操作反應, 即整理餐桌和洗碗盤。 在我們的日常生活中, 操作制約處處可見。 我們做的事大多都受過 操作制約的影響。 我們甚至會在一些不尋常的 情況中看到操作制約。 有一群科學家藉由 訓練鴿子成為藝術鑑賞家, 來展示操作制約有多強大。 科學家用食物當正面增強物, 教鴿子挑出莫內的畫, 忽略畢卡索的畫。 拿出其他藝術家的畫時, 科學家觀察到刺激類化的現象, 鴿子會挑出印象派的畫, 而不是立體派。 也許接下來他們會制約鴿子, 讓牠們畫出自己的名作。 (鈴聲)