100 Things Every Designer Needs to Know About People, 2nd Edition

43 Expectations of Frequency Affect Attention

Farid Seif, a businessman from Houston, Texas, boarded a flight in Houston with a loaded handgun in his laptop case. He made it through security without a problem. Seif was not a terrorist. The gun was legal in Texas; he simply forgot to take it out of his laptop case before his trip.

Security at the Houston airport did not detect the gun. It should have been easily seen by security personnel looking at the X-ray scanner, but no one noticed it.

The U.S. Department of Homeland Security routinely tests the ability to pass security screening with guns, bomb parts, and other forbidden items by sending them through with undercover agents. The U.S. government won’t release the figures officially, but the ...