University College London researchers have pinpointed the spot in the brain responsible for "change blindness," the phenomenon of missing big visual changes right in front of you, like a traffic light switching from red to green or a gorilla on a basketball court. The UCL psychologists used Transcranial Magnetic Stimulation (TMS) to temporarily switch off the parietal cortex of their subjects' brains. (Previous posts on TMS here and here.) With that region inoperable, the subjects couldn't notice a different face in front of them. From the UCL press release:
Professor (Nilli) Lavie said: "Because the parietal lobe is not part of the visual cortex it was at first surprising to find that activity in the parietal lobe is critical for visual awareness. We have always known that the parietal cortex was responsible for concentrating. But it was a surprise to find out it is also important for detecting visual changes in a scene. The finding that this region of the brain has both these functions, concentration and visual awareness, explains why we can be so easily deceived by, say, a magicians' trick. When we're concentrating so hard on something that our processing capacity is at its limits, the parietal cortex is not available to pay attention to new things and even dramatic changes can go unnoticed. If you're concentrating on what the magician's left hand is doing, you won't notice what the right hand is doing."
