Does the consumption of alcohol limit our attention span? An article in the July 10, 2006 Los Angeles Times described a study conducted at the University of Washington where 23 people were given enough alcohol to reach a blood alcohol level of 0.04% (half the legal limit in many states). A second group of 23 people drank no alcohol. The researchers then showed members of both groups a 25 second video clip in which two teams passed a ball back and forth and asked them to count the number of times one team passed the ball. During the clip, a person in a gorilla suit walks through the crowd, thumps its chest, and walks off.

Researchers found that 11 of the 23 participants in the control group saw the gorilla, versus 10 in the alcohol group. Verify that you reject the hypothesis that the two groups have the same probability of seeing the gorilla using α = .05.