Many people don't notice safety equipment until it's needed LOS ANGELES, Dec. 21 (UPI) -- A U.S. study showed people often do not recall things they have seen -- or at least walked by -- hundreds of times, researchers say. Lead author Alan Castel, an associate professor of psychology at the University of California, Los Angeles, said the study involved 54 people who worked in the same building. They were asked if they knew the location of the fire extinguisher nearest their office. Many of the participants had worked in their offices for years and had passed the bright red fire extinguishers several times a day, but only 13 out of the 54, or 24 percent, knew the location of the fire extinguishers. However, when asked to find a fire extinguisher, everyone was able to do so within a few seconds and most were surprised they had never noticed them. A few months after being asked the location of the nearest fire extinguisher, the study participants were asked again if they knew where the closest one was. All of them knew, Castel said. "Fire extinguishers are bright red and very conspicuous, but we're almost blind to them until they become relevant," Castel said in a statement. Making errors during training is useful. As with the fire extinguisher exercise, errors -- or simple oversights -- can teach us that we don't know something well and need to pay more attention in order to remember it. The study was published in the journal Attention, Perception, & Psychophysics.