They say it’s good luck to catch a falling leaf. But it’s hard to do. Why?
Ideally an apple and a leaf. But something alike, such as a ball and a scrap of newspaper will do.
It takes about one tenth of a second for your visual system to process what hits the back of your eye.
So our vision is always in one sense out of date. But the visual system looks ahead and helps us see the present even though the actual information hasn’t reached us yet. We can see a falling apple and catch it successfully. This is impressive because even at a leisurely 6 m.p.h. an object will have traveled about 10 inches further on and we have to anticipate that.
First try throwing the apple up in front of you and catching it as it falls. Even I, who have poor hand-eye coordination, can usually succeed. And my perception is I can see the apple all the time.
Next do the same with the scrap of newspaper. I tried various forms such a near-square, a random fragment, and narrow strips of various proportions. I think you will enjoy playing with a range of different shapes because their aerodynamics are varied and pleasing. Often scraps of paper behave like leaves.
Catching leaves or bits of falling paper is not like catching an apple. It is much harder. In fact for many shapes it’s nearly impossible and the leaf may be literally invisible for most of its descent. We can’t anticipate its location because it is too unpredictable and so we can’t see it, or even guess where it is, until it stops moving.
It’s controversial but experiments suggest we can be tricked into ‘seeing’ something that never happened but which our visual system was anticipating. There is an interesting article here, although personally I was not convinced by the explanation of the ‘bulging’ optical illusion.
The next in the series, 9/101 will be ‘The Sandman”.