Sensing phantom phone vibrations(手机虚幻震动) is a strangely common experience. Around 80% of us have imagined a phone vibrating in our pockets when it’s actually completely still. Almost 30% of us have also heard non-existent ringing. Are these signs of madness caused by digital culture? Not at all. In fact, phantom vibrations and ringing indicate a fundamental principle in psychology.
Psychologists use a concept called Signal Detection Theory to guide their thinking about the problem of perceptual(感知的) judgments. Working through the example of phone vibrations, we can see how this theory explains why they are a common and unavoidable part of healthy mental function.
When your phone is in your pocket, the world is in one of two possible states: the phone is either ringing or not. You also have two possible states of mind: the judgment that the phone is ringing, or the judgment that it isn’t. Obviously you’d like to match these states in the correct way. True vibrations should go with "it’s ringing", and no vibrations should go with "it’s not ringing".Signal detection theory calls these faithful matches a "hit " and a "correct rejection".
But there are two other possible combinations: you could mismatch true vibrations with "it’s not ringing"( a"miss"); or mismatch the absence of vibrations with "it’s ringing"( a"false alarm"). This second kind of mismatch is what’s going on when you imagine a phantom phone vibration.
What does that mean in terms of your phone? We can assume that people like to notice when their phone is ringing, and that most people hate missing a call. This means their perceptual systems have adjusted their bias(偏向) to a level that makes misses unlikely. The unavoidable cost is a raised likelihood(可能性) of false alarms-of phantom phone vibrations.
The trade-off between false alarms and misses also explains why we all have to put up with fire alarms going off when there isn’t a fire. It isn’t that the alarms are badly designed, but rather that they are very sensible to smoke and heat and biased to avoid missing a real fire at all costs. The outcome is a rise in the number of false alarms. These are inconvenient, but nowhere near as inconvenient as burning to death in your bed or office. The alarms are designed to err on the side of caution.
The writer tries to explain phantom phone vibrations         .

A．by analyzing some facts

B．by giving some examples

C．from the angle of biology

D．from the angle of psychology

According to the writer, the sense of phantom phone vibration is         .

A．natural and normal	B．harmful but avoidable
C．unusual and unavoidable	D．common but unhealthy

When we judge correctly that "it’s not ringing", this is called a "       ".

A．hit	B．miss
C．false alarm	D．correct rejection

What does the underlined part in the last paragraph mean?

A．Better late than never.

B．Better safe than sorry.

C．Fight over the smallest things.

D．He who makes no mistakes makes nothing.