Distractions and interruptions

Did you know that there is a whole branch of psychology devoted to the impact of interruptions and distractions on learning, memory, performance, productivity, and decision making?


First, there is less distinction than you might think between a distraction (something that happens in the background and impairs attention or function, but does not require that one actually switch tasks) and an interruption (something that makes one stop the current task, address something else, and then return to the current task). The inevitable impairment of focus, concentration, accuracy, and efficiency, is mostly a matter of context and degree.

Interruptions have traditionally been described as existing on a scale of intrusiveness, from those that require completely disengaging from the current task cognitively and physically (putting the guitar down and going to the phone to talk to the caller) to those that involve varying degrees of attentional and activity shift, but feel as if the primary task is still ‘active in the background’ (answering an instant message while preparing ingredients for dinner ). 

Distractions have also traditionally been described as existing on a scale of intrusiveness, from those that feel as if they interfere (a conversation in the next room while talking on the phone) to those that feel as if they are essentially invisible (background music or traffic sounds).

Current information suggests that these are false constructs, which lead us to misunderstand and underestimate the impact of both interruptions and distractions.

A more accurate (but still evolving) model is that we have a limited and very finite amount of ‘processing’ resource that is expected to cope with a volume of internal and external stimuli that would be overwhelming if we were unable to filter and selectively focus/attend. When we direct our attention to one activity, everything else is slowed to a crawl that is hard to distinguish from inactivity. A useful analogy is the way we generally use our computers: we work on one document or program at a time, though others may be ‘open’ and available - IF we chose to change to a different window or document or program. Whenever we work on one cognitive task, all others are essentially on hold.

Some things worth thinking about:

  • When we switch from one task to another, there is a ‘switching cost’ with a delay measured in seconds to minutes before one resumes full function in the second task, and a measurable decrease in what is retained and usable in memory from either task. The delay and memory impairment (or interference with learning) varies depending on circumstances, but the more cognitively demanding either task is, the higher the cost, the longer the delay, and the greater the chance for error.
  • In studies of simple computer games, it takes about 15 seconds after an interruption (to answer a question on the screen such as: ‘Is this dot red or blue?) to get back to baseline speed and longer to get back to baseline accuracy.
  • Distractions (activity in the background requesting our attention) require work to filter out. This work steals ‘processor cycles’ from our primary cognitive task, slows us down, impairs memory and learning, and increases the risk of error. It also results in attentional fatigue and it becomes harder to maintain focus as the strength and duration of the distraction increases.
  • Switching to a new task after completing the first task involves much less mental effort (switching cost) and is faster and associated with less fatigue and less change of error. (There appears to be a significant amount of cognitive effort required to maintain a task ‘open’ in the background, and this cognitive resource is freed up when the task is completed.)
  • Doing two things at once means that we are attempting multiple task switches with a steady increase in switching costs. This results in decreased speed in all the tasks, decreased accuracy, increased fatigue. It can be seen even with fairly simple motor tasks, but becomes very significant as the task demands increase.
  • There is some information to suggest that the reason some background activity seems to help us focus is that it is so familiar and neutral that it does not require any significant effort to ignore it. This explains why we hardly notice familiar noises in our own car, but are uncomfortably aware of them in a borrowed car, or why some music seems to soothe us and other music makes it hard to concentrate. 
  • If we are humans, we do not multitask, we serially single task.
  • ‘Thrashing’ is a term used for circumstances where people attempt to multitask aggressively and end up very active but getting nothing done. It is akin to a voluntary form of attention deficit disorder.

As I read about this over the last few weeks, I kept thinking about how this applies to me trying to work as a physician, forced to simultaneously attend to the patient, the EHR, and the barrage of interruptions and distractions inherent in primary care. Arrrgh.


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