科普園地 4 分鐘閱讀
Bruce, Angela, Wesley
“If you could keep only one of your five primary senses—touch, smell, hearing, sight, and taste—which would it be?” What a horrible question! Think of it as a “thought experiment.” Given that the verb “see” can replace “know” or “understand” as in “I see what you’re saying,” sight may be the most important of the five primary senses. On the other hand, judging from how many people everywhere listen to music on their smartphones these days, hearing cannot be far behind. In any case, pleasant and unpleasant emotions can be connected to all five senses.
Most would agree that the sounds of flowing water or a baby laughing are pleasant to hear. Many would also agree that the sounds of screeching vehicle brakes or a mosquito are not. In a study, researchers arranged for subjects to listen to a wide variety of sounds. From a long list, the participants rated fingernails scratching along a chalkboard as the most unpleasant sound. People who have been schooled in classrooms with chalkboards would likely agree. The sound actually makes many people shiver.
Scientists wanted to know why. They monitored their subjects’ reactions to fingernails scratching a blackboard in terms of stress levels. They found that the scratching sound changed the participants’ skin conductivity considerably. Previous research had revealed a close relationship between skin conductivity and the part of the brain that registers negative emotions. The new study confirmed that this scratching sound did cause a physical stress reaction. Maybe this explains why whiteboards and markers are quickly replacing blackboards and chalk.