Have you ever felt your life go into slow motion as you realize something bad is happening

？ You might have just knocked over a wine glass or noticed a car hurtling towards you, for example. Now scientists have measured exactly how much these attention-grabbing(引人注意的)events slow down our perception of the world around us.

Another example of the world appearing to slow down is when you are hanging on the phone waiting for someone to pick up at the other end. If your attention wanders while you're waiting, then suddenly switches back,you will probably hear what seems like a longer than usual silence before hearing the dialling tone again. For you, time will have momentarily slowed.

To see how our perception of time changes when something new happens, Vincent Walsh and his colleagues put headphones on volunteers and played eight beeps to their right ears. The gap between each beep was exactly i second, except for the gap between the fourth and fifth beeps, which the scientists could make shorter or longer. They altered the length of this gap until the volunteers estimated it was the same length as the other gaps. The researchers found that, on average, people judge a second slightly short, at 955 milliseconds.

In the second part of the experiment, the first four beeps were played to the subjects' right ear, but the other four were then played to their left. Again, the volunteers were asked to estimate when the gap between the fourth and fifth beeps was the same as the others. This time they judged a second to be even shorter at 825 milliseconds long.

Perceiving a second to be much shorter than it is makes you feel as though the world has gone into slow motion, since less happens in that slice of time. Walsh thinks the effect could have evolved to give us a fraction more time to react to potentially threatening events.

Last year, Kielan Yarrow, a British psychologist found a similar effect with vision. When you glance at a clock, the first second will seem longer than it really is.

Yarrow's results showed that time appeared to slow down by a similar amount as Walsh found. Previous studies have shown that cooling the body slows down our perception of time while warming it up has the opposite effect.

After you noticed a car hurtling towards you, you might feel that ______.

A．the world around you had slowed down

B．something bad was going to happen

C．life had suddenly become meaningless

D．people's life was so fragile