閱讀筆記 S3016 The Sound of Food

Science 3016
The Sound of Food
Is a reflex something that happens naturally, or can be taught?
In the late 1800s, Ivan Pavlov was a scientist living and working in Russia. He had been studying how dogs digest food. He noticed something very interesting. Before he fed the dogs, they would begin to salivate, or produce saliva. When they saw Pavlov take out their food, they knew he would feed them soon. The saliva helped them digest the food.
Watching this made Pavlov curious. He wondered if something other than food could have the same effect. He decided to do some experiments to test his idea. Just before he fed the dogs each day, he rang a bell. After doing this many times, he tried ringing the bell without feeding the dogs. Sure enough, the dogs salivated at just the sound of the bell. Each time Pavlov rang the bell, he got the same results.
In Pavlov’s experiments, the bell was the stimulus.  It caused the effect—salivation—that he was trying to produce.  Before Pavlov trained the dogs, the sound of a bell didn’t have any effect on them. Pavlov trained the dogs to link the sound of the bell with food. The animals got so used to this idea that even when there was no food, they still reacted the same way.
The dogs’ response was a reflex. If you tap just below the center of your knee, your leg will kick. You don’t kick on purpose, it’s just a reflex. If you put your finger in a newborn baby’s hand, the baby will grasp it. Shine a light at someone’s eyes, and their pupils will shrink. Living things are born with all kinds of reflexes. Each time a stimulus is present, the body behaves the same way. Through his work with dogs, Pavlov was able to show that reflexes can be taught, too.