Pete’s Blog

Sheffield Advanced Motorcycling - Pete Harley (National Observer

Editors note: Here is the third article, a little earlier than planned, written by Pete Harley (Observer). We are very grateful to Pete for taking the time to produce these well-researched articles. Share them with your friends to that the SAM Club rich with very talented bikers. Thank you.

Hello again (probably for the last time)

In the last article I gave  the link ( to the following illusion.

Sheffield Advance Motorcyclists - learning whilst having fun!

It is well worth exploring this website because there are lots of fascinating illusions there; some, like this one, involving movement but there are others which are static. I’m going to show a couple more here.

First one, there are two dots in the following video – one chasing the other but which one is doing the chasing?

Before I say anything more, let’s look at a few more.


By now, we have all, probably, seen the gorilla video

If you’ve not seen it before then try the test outlined in the video.  It shows quite a startling effect, if you’re not expecting to see something then you may not see it!

Have a look at the next video which illustrates a very similar feature:

This one was another example where an individual was concentrating on one particular thing and so didn’t notice a fundamental change.

The point about these illusions is that your brain has shown you what you expected to see, not what was there.  This can be rather critical: for example, if you are at a T-junction waiting to turn right then you have a lot to do.  You need to be aware of traffic approaching from both the left and the right and make judgements about their speed and whether or not they may, themselves, turn right or left into your road.  You probably have, in the back of your mind, the idea that bigger (a lorry) is more dangerous than smaller (a car) – in that situation are you really confident that you would notice the cyclist approaching at speed on your side of the road?  This might be compounded by the effect known as “looming” ( in which it has been shown that it is much more difficult to judge the speed of something coming straight towards you as opposed to travelling on a diagonal (across the background).

All of this may be particularly relevant just now as we are back on the road following the coronavirus lockdown. It is likely that we will go onto roads with which we think we are familiar and on which we “expect” to see various things – but they may have changed.  The main point of all this is to make you consider that what you “see” may not accurately represent what’s actually there!

Take care – stay safe,



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