something that confuses you so that you see, understand, remember, etc. things in the wrong way 引起错觉（或记忆紊乱）的事物
One of the problems of old age is that your memory can start to play tricks on you.
老年人的问题之一是记忆可能紊乱起来。
Was there somebody standing there or was it a trick of the light?
是真的有人站在那儿还是光线引起的错觉？