With events at Fort Hood likely to cast a shadow over the coming days, I thought I would direct your attention to something more light-hearted. Today marks the 40th anniversary of Sesame Street. In a world of darkness and cynicism, it is important to remember and celebrate these nuggets of innocence and joy. But before you think that I have gone completely sappy, have a look at this alternative version of Sesame Street’s Count singing about what he loves to do best. If you are young enough then you probably hear the Count “counting.” If you are a bit older, then you probably heard something completely different! Shame on you.
This is an auditory equivalent of the visual Kaniza illusion where we fill in missing information based on past experiences. For example, in the figure on the right, you should easily see a white triangle that is not really there. The brain interprets this configuration as a white triangle floating above three dark circles. It is the most likely explanation that would produce this pattern and so the brain creates the perception of this triangle. However, the amazing thing about these illusory effects is that the brain generates neural activity in the networks that would be active if the missing information was really there. In other words, these illusions are based on real neural activity. In which case, if someone says they have heard or seen something that isn’t really there, then as far as the brain is concerned it is! Now that’s spooky.