Everyone tends to float off into space once in a while and fail to see what is sitting there right in front of them. Recently researchers decided to put the theory of “inattentional blindness” to the test: the unicycling clown test. They documented real-world examples of people who were so distracted by their cell phone use that they failed to see the bizarre occurrence of a unicycling clown passing them on the street.

The study is published in an upcoming issue of Applied Cognitive Psychology.

Compared with individuals walking alone, in pairs, or listening to their ipod, cell phone users were the group most prone to oblivious behavior: only twenty-five percent of them noticed the unicycling clown. The walkers not using a cell phone noticed the clown over fifty-percent of the time.

Furthermore, the cell phone users had difficulties performing even the simple task of walking, an action that should require relatively few cognitive resources. They walked more slowly, changed direction more often, were prone to weaving, and acknowledged other individuals more rarely.

Dr. Ira E. Hyman, Jr. at Western Washington University, head researcher of the study, says: “If people experience so much difficulty performing the task of walking when on a cell phone just think of what this means when put into the context of driving safety. People should not drive while talking on a cell phone.” Furthermore, the research shows that the level of familiarity with the person’s real-world environment does not affect their attentional awareness.