Even a three-second interruption can double error rate in important tasks

Saturday, January 19, 2013 by: David Gutierrez, staff writer
Tags: mental focus, tasks, interruptions

(NaturalNews) Interruptions of even a few seconds can dramatically increase the error rate of a person working on a complex task, according to a study conducted by researchers from Michigan State University and the Naval Research Laboratory and published in the Journal of Experimental Psychology: General. The study was funded by the Office of Naval Research.

The study sought to measure the effect of the brief interruptions that are now a common feature of everyday life, from the ringing of a cell phone or text message to a notification on a computer screen. The findings suggest that these interruptions can have serious consequences for people such as surgeons or airplane mechanics, who work on complex tasks that other people's lives depend on.

"What this means is that our health and safety is, on some level, contingent on whether the people looking after it have been interrupted," lead researcher Erik Altmann said.

In one of the first studies to measure the effect of interruptions on difficult tasks, the researchers instructed 300 people to perform a procedure that relied upon performing a specific sequence of events - thus simulating a train of thought and making participants vulnerable to forgetting where in the sequence they were. One such task consisted of hitting a key to identify whether a letter was closer to the beginning or end of the alphabet. Even uninterrupted, all participants made a small number of errors.

The researchers then interrupted some participants with instructions to type two letters, a task that lasted an average of 2.8 seconds, then return to the sequence. Even this brief interruption caused the participants' error rate to double. A 4.4 second interruption actually tripled the error rate.

"Contextual jitter"

Notably, the participants did not exhibit any time lag between completing the interruption and resuming work. This suggests that even though the participants had forgotten where in the sequence they were, they remained unaware of this fact. The researchers labeled this phenomenon "contextual jitter."

"When someone is momentarily interrupted or distracted and then returns to their task, they may do so without obvious hesitation, but with an increased chance of resuming at a different point in their train of thought than they might have otherwise," they wrote.

Because the length of the interruptions was not any greater than the amount of time it took participants to complete each step of the task, the researchers did not believe that it was a disruption of their timing that produced the jump in errors.

"So why did the error rate go up?" Altmann said. "The answer is that the participants had to shift their attention from one task to another. Even momentary interruptions can seem jarring when they occur during a process that takes considerable thought."

A way to avoid this problem, the researchers suggested, is to try and make the environments where people are performing complex, important tasks as interruption-free as possible.

"So before you enter this critical phase: All cell phones off at the very least," Altmann said.

Sources for this article include:

http://www.sciencedaily.com/releases/2013/01/130107100059.htm
http://www.theatlantic.com