Even brief interruptions while working can double errors

Researchers led by Michigan State University who studied 300 people performing a sequence-based procedure on a computer found that interruptions of about three seconds doubled the error rate.

"Brief interruptions are ubiquitous in today's society, from text messages to a work colleague poking his head in the door and interrupting an important conversation," said Erik Altmann, lead researcher on the study.

"But the ensuing errors can be disastrous for professionals such as airplane mechanics and emergency room doctors," Altmann said in a statement.

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

Study participants were asked to perform a series of tasks in order, such as identifying with a keystroke whether a letter was closer to the start or the end of the alphabet.

Even without interruptions a small number of errors in sequence were made.

Sometimes participants were interrupted and told to type two letters - which took 2.8 seconds - before returning to the task. When this happened, they were twice as likely to mess up the sequence.

Altmann said he was surprised that such short interruptions had a large effect. The interruptions lasted no longer than each step of the main task, he noted, so the time factor likely wasn't the cause of the errors.

"So why did the error rate go up? 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," Altmann said.

The study was published in the Journal of Experimental Psychology: General.