心理学家曾作过一个试验:将一只跳蚤放进杯里,开始跳蚤一下就能从杯里跳出来。然后在杯上盖上透明的盖,跳蚤仍然会往上跳,但碰了几次盖不能从杯子里跳出后,慢慢就不跳那么高了。这时,再将盖拿走,却发现那只跳蚤已经永远不能跳出杯子了,因为它失去了信心,它已将目标定到了不及杯盖的高度。 Psychologists have done a test: a flea into the cup, flea began to jump out from the cup. Then the cup is covered with a transparent cover, the flea will still jump up, but after a few touches the lid can not jump out of the cup, it does not jump so high. At this moment, take the lid off, but find that the flea has never been able to jump out of the cup, because it has lost its confidence and it has set the target as low as the lid.