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You have to try this – Change Blindness

February 9, 2012

Before starting on the ‘You have to try this’ post of the day, I wanted to check – have any of you gone back and tested what I told you about the sine wave speech demonstration? Can you still understand it?

Our brains are amazing machines. If you think about it for a minute, there are so many sights, smells, sounds, tastes, etc. which surround us all the time, and which our brains have to filter through and process appropriately.

As I type this, I am surrounded by sights – still objects such as the table, my water bottle, a bag of nuts and raisins I am snacking on, my computer, chairs, papers, a notebook and pen, walls, a door, windows, etc., and moving objects – Ben is sitting near me and moving papers around, typing, and looking back and forth between the computer and his papers. There are background noises from the washing machine, from passing cars, from Ben typing and occasionally talking or singing to himself or tapping out a tune (it makes the days more interesting ;-)), and I can hear myself typing, myself breathing (and yawning), and myself chewing. This is only the very start of the stimuli my brain is currently exposed to, but even this sounds like a lot. So how is my brain dealing with it? Am I fully processing every bit of this information equally?

Watch the videos below and let’s find out. (Note: Each of the two videos takes about 90 seconds, and it is best to watch them in order).

Now, try this one. And if you skipped the first video because you thought you had already seen it in Psychology class, try this one anyway:

Did you see everything that was going on in both videos before the surprise was pointed out? Probably not, unless you have seen these videos before. And even though I have seen both of these in the past, I still missed something from the second video because I had forgotten about it.

These are examples of change blindness where you are asked to focus on one thing, and something else happens. These studies suggest that our limited cognitive resources are focused on what is important, or what we think is important, possibly at the expense of other things happening around us. I would argue, however, without giving away what happens in the video, that if we were the people passing the ball in the video, and the surprise was the real thing, then we would notice. We are still programmed to notice danger, but we may notice it less quickly if we are very focused on something else.

There are other change blindness demonstrations which show that even if we are looking directly at something, and in fact, looking for a change, we don’t always see it.

This picture of an airplane (or perhaps jet) is flashing, so if you are sensitive to this, you may not want to look. Click here to view. Can you see what is changing each time the picture flashes? Hint: something is appearing and disappearing. The answer is below, so don’t cheat.

Have you seen it yet? The large engine right under the wing is appearing and disappearing, and if you watch again, it will be hard to miss.

This type of change blindness demonstration suggests that our brains actually fill in the gaps in an image, and presumably the world around us, using our pre-existing knowledge. We know what a jet looks like, and so we don’t necessarily notice when something about it is slightly different. This aspect of change blindness, although perhaps not as exciting to demonstrate (i.e., there is no major surprise which takes place – just a changing picture), is particularly interesting to me because this demonstration suggests that we rely on our semantic memory – our knowledge of the meanings of words and objects and what they look, sound, taste, smell like – to make sense of the world around us, and to save ourselves from having to notice and fully process and store every detail.

So, going back to the question which I asked at the start of this post, I guess the answer seems to be that we don’t process, or at least store, every single detail of the world around us. Instead, we are able to use what we already know, and also focus our attention on certain aspects of a scene, in order to conserve cognitive resources while still creating the most complete picture of our environment.

In my current environment, I know that I am chewing on my snack and breathing, and that Ben is likely to randomly start singing, and I am aware that these things are occurring around me, but I don’t have to notice and remember every single detail, or every word that Ben sings…as much as I love the singing, of course. 😉

And now, for the usual poll – remember, no one can see who has answered or what your specific answer was. We can just see the number of people who have voted one way or another.


For more information, and a  couple of other great examples of change blindness, check out these videos:

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