Number of words – 534

Multitasking, whereby we deliberately do several tasks simultaneously, erroneously appears to be an efficient way of getting a lot done. It is much beloved by teenagers and busy workers, but in fact, all the evidence points to severe degradation of performance, increased errors, and a general lack of both quality and efficiency. Doing two tasks at once takes longer than the sum of the times it would take to do each alone. Even as simple and common a task as talking on a hands-free cell phone while driving leads to serious degradation of driving skills. One study even showed that cell phone usage during walking led to serious deficits: “Cell phone users walked more slowly, changed directions more frequently, and were less likely to acknowledge other people than individuals in the other conditions. In the second study, we found that cell phone users were less likely to notice an unusual activity along their walking route (a unicycling clown)” (Hyman, Boss, Wise, McKenzie, & Caggiano, 2010).

A large percentage of medical errors are due to interruptions. In aviation, where interruptions were also determined to be a major problem during the critical phases of flying—landing and takeoff—the US Federal Aviation Authority (FAA) requires what it calls a “Sterile Cockpit Configuration,” whereby pilots are not allowed to discuss any topic not directly related to the control of the airplane during these critical periods. In addition, the flight attendants are not permitted to talk to the pilots during these phases (which has at times led to the opposite error—failure to inform the pilots of emergency situations).

Establishing similar sterile periods would be of great benefit to many professions, including medicine and other safety-critical operations. My wife and I follow this convention in driving: when the driver is entering or leaving a high-speed highway, conversa- tion ceases until the transition has been completed. Interruptions and distractions lead to errors, both mistakes and slips.

Warning signals are usually not the answer. Consider the control room of a nuclear power plant, the cockpit of a commercial aircraft, or the operating room of a hospital. Each has a large number of different instruments, gauges, and controls, all with signals that tend to sound similar because they all use simple tone generators to beep their warnings. There is no coordination among the instruments, which means that in major emergencies, they all sound at once. Most can be ignored anyway because they tell the operator about something that is already known. Each competes with the others to be heard, interfering with efforts to address the problem. Unnecessary, annoying alarms occur in numerous situations. How do people cope? By disconnecting warning signals, taping over warning lights (or removing the bulbs), silencing bells, and basically getting rid of all the safety warnings. The problem comes after such alarms are disabled, either when people forget to restore the warning systems (there are those memory-lapse slips again), or if a different incident happens while the alarms are disconnected. At that point, nobody notices. Warnings and safety methods must be used with care and intelligence, taking into account the tradeoffs for the people who are affected.

Excerpted from ‘The Design of Everyday Things’ by Don Norman