Now test your concentration. View the video clip, below.
According to one source, and I can't verifiy it's reliability, about half of people who view this video do not see the gorilla due to the phenomenon of "inattentional blindness." My husband SAM said "put a nekkid woman in there and I bet people wouldn't miss it." Ah. He'd sweep up the research grant money with that proposal.
Inattentional blindness may help explain the higher rate of car accidents by cell phone users. It may also explain why lifeguards have trouble seeing bodies at the bottom of the pool. Finally, and I have no reference for this, it may explain why my daughters never see their dirty socks strewn in the middle of the playroom floor.
To learn more about inattentional blindness, read a summary written by Daniel Simons here.
*Simons, D. J., & Chabris, C. F. (1999). Gorillas in our midst: Sustained inattentional blindness for dynamic events. Perception, 28, 1059-1074.