We’re now two days away from the Brain Awareness Expo at the WOW Hall in Eugene, OR! Last night we finalized the activities our museum will be presenting at the Expo and I got really, really excited. One of the interactive demos we’ll bring with us involves change blindness, a fascinating phenomenon of visual cognition in which significant changes can go unnoticed by observers. This phenomenon has often been used to dupe many prank victims in some pretty revealing hidden camera clips, like this one:
These hilarious videos are also valuable for their demonstration of typical selective attention as it is taken for granted by people everyday. We only see what we think is important, and we typically ignore everything else. This is an organization of priorities in the brain with obvious benefits: changes occur in our environment all the time, and we wouldn’t want to be distracted by random things when we are trying to focus on something important, i.e. I am carefully stalking a small tasty animal in an African savanna and if I get distracted by unrelated and tiny movements in the trees around us, I might lose my chance to eat (frowny). However, in our contemporary 21st century world, this kind of selective attention can have different consequences. In a lot of writings on selective attention and change blindness, researchers note the potential impact on the reliability of eye witness statements in criminal cases (see some resources at the end of this post). Of course, issues of eye witness accounts after the fact involve other neuro factors, including the power of suggestion (“Was this the man you saw that night?!”) as well as memory and recall, but selective attention and change blindness do force us to wonder if the way the world is perceived in the moment is even reliable.
Videos like the one above have gained a lot of popularity over the last few years (as has a lot of neuroscience research, YAY!!!) and may actually have a corrupting effect on further research conducted in the same format. I, for one, am going to be very wary of people who ask me for directions on the street and in which conversation we are rudely interrupted by people carrying something right between us (especially if that something is actually a gigantic picture of the “tourist’s” face…). However, there are some even simpler tests that demonstrate change blindness, and these are pretty much incorruptible since they work even when the subject knows what’s going on. The principle is simple: two images alternately flash at regular intervals. The two images are nearly identical except one change has been made between them. Sometimes the change is something big – like the color of a building is different – and sometimes it’s small, like a rock has been removed from the background. Whatever the change is, it is observable and it is consistent. Easy enough, the challenge is to spot the change and identify it as quickly as possible. Easy…. nope. Trust me, there are few things as infuriatingly frustrating as these damned tests. If you’d like to start your morning off right with a proper rage, do some of these first thing. Sometimes people are able to spot changes pretty quickly, but a lot of the time it takes an embarrassingly long amount of time to get it. Then, after you’ve found the change, it’s the only thing you can notice about the switching pictures. At that point, you’ve taught your cognitive brain to focus on that one change, making you effectively blind to any other changes that might occur in the scene (GAH!!!). There are lots of change blindness demos online put out by researching institutions, some I’ve linked below. (Warning: not only can these demos be insanely frustrating, they can also cause headaches or possibly induce seizures since they flash at different speeds, as necessitated by the test function. Please be careful).
U of Idaho, Go Cognitive (these are fun, because you can time yourself for each different set)
For more information and some scholarly research, IU has included some really fabulous links to pdfs on their Cognitive Science Software page.
Nova ScienceNow also has a funny video and some background on change blindness (as well as lots of other really awesome things).