Feedback provides informative clues about what is happening, clues about what we should do. Without it, many simple operations fail, even one as simple as getting into elevator. Proper feedback can make the difference between a pleasurable, successful system and one that frustrates and confuses. (P138)
Sound of the machines is essential in human --- machine communication; it is a way that machines provide feedback and reassurance; it is a natural side effect of the working of physical devices. Though sound, people may know if the machine is operating properly. Moreover, people can tell whether the machine has an operating problem according their abnormal sounds.
This recalls my experience of two types of air conditioner: In the old days, the air conditioner is a unity that combined with its generator (must be installed on windows). This type of air conditioner can make such huge noises that I would have bad dreams during my sleep. Several years later, the split type room air conditioners, this type of air conditioner is separated with its generator. That means the air conditioner itself can be hang on anywhere of the room and its generator is installed outside the house. The new air conditioner became instantly bestseller once launch on the market. It is much more quieter than the old one. The only sound from the air conditioner is the wind that blew out. The commercials of the new air conditioner were actually humor too. They analogize the sound of the old generation air conditioner as a howling train passing by that give people the scene of nightmares, and the sound of the new generation air conditioner as the lullaby for babies. The commercials maybe exaggerated but it truly reflected that how the sound of machines affects people’s life. But then another problem arises. In the past people can know the air conditioner is on by its sound, but for the new type of air conditioner, it is so quiet that people couldn’t notice it is operating and that often forget to turn it off before leaving the room. Actually both generations of air conditioner has a light indicating that the machine is on but in most cases the air conditioner is hung so high and the light is too small for people to see. So the sound became an important indicator that tell people the machine is operating or not.
Every piece of equipment has its own code for beeps, its own code for lights. A small red light visible on an appliance could mean that electric power is being applied, even though the appliance is off. Or it could mean that the unit is turned on, that it is working properly. Then again, red could signal that it is having trouble, and green could mean it is working properly. Some lights blink and flash; some change color. Different devices can use the same signals to indicate quite different things. Feedback is meaningless if it does not precisely convey a message. (P140)
This paragraph reminded me my experience with my new camera. Everyone will have the same experience that once you bought a new camera, you just can’t wait to explore its wonders. But before this amazing experience begins, you will have to fully charge the battery. When I plugged in the charges, something made me confused. The light on the charger appeared green! So I thought: “Hmmm…maybe this battery was somehow charged. So I put the battery back into the camera. But I couldn’t turn it on! So I thought: “What’s wrong??? The battery is charged. Something wrong with the camera??” And at that moment, I felt like someone punched my stomach: “Damn! I don’t want to go all the way back to HongKong to exchange it!!” What happened next? Luckily I was too perseverant. I kept trying and trying. Finally I’ve found out what the problem was! It turn out that the green light indicates “battery is charging”. Is that confusing?? As we all known, the green light usually indicates “battery charged”. Normally, when the battery is charging, the light appears red or orange. If it is a green light, usually it flashes. I think this is a good example to illustrate that manufacturers should consider that customers are used to a set of indicators. It is somewhat a universal sense that green light indicates “charging finished”. Therefore the manufacturers should follow these rules to reduce customer’s confusion or frustration.
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