So if you wiggle a coffee cup in front of the camera, you're feeling that in your back, and amazingly, blind people got pretty good just by feeling it in the small of their back.
比如，如果你在相机前摆动一个咖啡杯， 就会通过背部感受到它， 而且令人惊讶的是，盲人很擅长于 仅仅通过背部的一小块的感受 来确定相机前的东西。