To see how it works, imagine a frog in a jar: by itself the amphibian might not be able to jump out, but if the jar is in a rumbling truck the frog might get the boost it needs to make it.

• 要想知道这种效应如何运作，不妨想像一只位于瓶里的青蛙；单凭一己之力，该两栖动物是跳不出瓶子来的，但如果把瓶子置于一辆摇晃的卡车上，瓶里的青蛙就有可能获得一阵助力，而跳出瓶来。