27 April

Change Blindness and Inattentional Blindness   Friday, April 27, 2012

Posted by : Ryan Clark
Please watch the short video above before reading any further.

What you (hopefully) just experienced is the phenomenon of inattentional blindness. Our sense organs produce such a large and continuous volume of information that it is simply impossible for us to pay attention to all of it at once. As a result, obvious things such as “gorillas in our midst” can easily be overlooked. See the video below for another interesting demonstration.

If we can have such massive gaps in our visual awareness, why is it that we feel as though we are aware of the entire scene? It may be due to the fact that we have “transient detectors” that draw our attention to sudden changes. You can easily detect the change taking place in the following image, for example:

We likely evolved these transient detectors to help us detect the sound of a twig snapping as a panther stalks us, or to detect the visible sway of grass blades produced by a concealed lion. (Apparently we did not evolve transient detectors tuned to help us detect gorilla interlopers during basketball drills!) However, even these transient detectors can be tricked or “washed out”. Can you see what’s changing in the next image?

The difficulty you may have had in finding the change is due to the phenomenon of change blindness. It is not necessarily a lack of attention that causes the difficulty, but the fact that your brain does not have a complete representation of everything that you’re seeing, and therefore cannot make an accurate comparison of the two states. Even when the change is not covered up by a “flicker”, you may still not notice it, as shown in this image:

Further, even if there are no decoy changes to overload your transient detectors, you may still not notice the change! See the following video.

Even massive changes such as this one can go undetected, if they occur slowly enough.

In a future post we will discuss what we feel these phenomena imply about how the mind works, and how that will affect our future efforts.

See the following websites for more on change blindness and inattentional blindness:

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