Cliffhangers in the ED. St.Emlyn’s

bandwidth in the ED St.Emlyn's

I was fortunate enough to be on receiving end of a comprehensive introduction to human factors, courtesy of Dr Gareth Grier (@uncgiggaz), who I am lucky enough to work with as one of my bosses. Amongst the many concepts we talked about, a common denominator was bandwidth, something that many of us are already familiar with and others may be new to.

What is Bandwidth?

We conceptualise bandwidth essentially as the amount of resource we have available to be able to attend to tasks. We cannot concentrate on an indefinite number of tasks, we have a finite capacity to concentrate and attend to events. Bandwidth, as with a lot of medical human factors, appears to have been borrowed from aviation safety. It is a term to use to communicate when one is overloaded with work. But what is it? This concept is likely to be a catchy way of describing what psychologists have studied and theorised about for years and would probably recognise as a form of working memory.  Working memory is a theoretical construct that was first proposed in the 1960’s by Baddeley and Hitch.  It was theorised as a means to elaborate upon the concept of short term memory.  The components of the working memory model are shown below:

bandwidth in the ED St.Emlyn's 2

The central executive is effectively the boss.  It co-ordinates and controls the activities of the other components.  It is the mechanism that decides what we pay attention to and when.  The phonological loop is the inner voice and allows to repeat and rehearse numbers and words we wish to recite.  The visuospatial scratchpad is akin to an inner eye, and allows us to visualise information.  The episodic buffer is essentially a temporary storage which combines all the inputs from the phonological loop and visuospatial scratchpad.  An alternative, and simpler way of viewing this is as shown here:

Working Memory Concept bandwidth in the ED St.Emlyn's

I personally like to think of bandwidth as an analogy for working memory.  It is the way that we deal with new information in the ED.  In 1956 George Miller famously promoted the idea that the average human is able to hold 7 +/- 2 bits of information in what is now known as working memory.  Clearly there are exceptions to this rule, and some individuals will perform better or worse than others in this regard.  These bits of information can be enhanced through ‘chunking’ groups of information together.  However you describe our ability to attend to information, whether as bandwidth or working memory, a major factor that impacts on our ability to work effectively is cognitive load.  Cognitive load is the amount of mental effort that is being expended at any given time.  Cognitive load is a significant factor with regards to how we work in the ED.  Distractions and interruptions add to cognitive load and decrease the amount of resource we have available to attend to other problems.  We should strive to avoid distracting and being distracted whilst attending to tasks, but the reality is that this happens all the time.  Imagine when one is signing an ECG with a phone ringing in the background, a patient being rowdy, a nurse waiting to get some analgesia prescribed and a junior colleague wanting to discuss a patient.  This is not an uncommon scenario and this is illustrative of the cognitive load we are subjected to.  How can this be mitigated?  Be clear with colleagues that whilst you are completing a task you should not be interrupted, and indeed this attitude should be accepted and encouraged within the department.  Increasing cognitive load results in error.

The Zeigarnik Effect

Bluma Ziegarnik was a Soviet psychologist/psychiatrist. If you have ever watched a television series, you will be well familiar with the Zeigarnik effect, or better known in this context as a cliffhanger. The eponymous effect is incredibly important to be aware of, especially in busy environments such as the Emergency Department. The Zeingarnik effect was first theorised after the observation that a waiter would be better able to recall the order of an unpaid bill than that of a paid one. This idea was supported through a series of experiments. The effect effectively means that one will continue to ruminate and have better memories of interrupted or incomplete tasks, than completed ones. The videogame ‘Minecraft’ is perhaps the ultimate example of the Zeigarnik effect, which can partly explain its inexplicable success; it is an endless uncompleted task. If this is considered in terms of bandwidth, one can see how quickly a series of unfinished/interrupted tasks can chip away at ones ability to attend to new events or problems. In other words, if one doesn’t complete a task, it will reduce the ability of the individual to attend to further tasks. The good news is that the Ovsiankina effect, named after a colleague of Zeigarnik, suggests that individuals are motivated to return to complete interrupted tasks. It is the manipulation of these two effects that makes some advertising strategies so successful.

The Zeigarnik effect is also useful for those who are studying. It is commonplace for people to endorse studying for short amounts of time and then have a break, before returning to study. This is a practical application of the Zeigarnik effect. Performance and recall is better if one takes regular breaks and disrupts their study than if one slogs through an entire topic in one sitting.

Unfortunately the Zeigarnik effect is also likely the reason that we struggle with regret. ‘If only I had done x,y or z….’ is this effect working once more. We ruminate and lose sleep over our sense of inaction – cheers for that Bluma.

I think this effect is a useful thing to be aware of, especially during a busy shift.  Avoid taking on endless tasks without acting to resolve at least some of them.  In doing so you will avoid saturating your bandwidth, you will avoid making errors with subsequent tasks as they present themselves and you will avoid stressing yourself out!


It’s not all doom and gloom! With expertise, there becomes less reliance on working memory and more reliance on heuristics.  A heuristic is otherwise known as a rule of thumb.  As we gain more knowledge and more experience we develop new heuristics that allow us to make quick decisions.  In certain situations our gut instincts, or heuristics, can save us time and require less cognitive load, therefore gifting an individual more bandwidth.  These heuristics are particularly useful in time critical scenarios, such as though we may face in the resuscitation room.  This is a topic that Gerd Gigerenzer has written about extensively.  I would argue that his book ‘Gut Feelings: Short Cuts to Better Decision Making’ should be on the reading list for every Emergency Physician, young or old.

So What Does This All Mean?

  • We have limited bandwidth
  • Bandwidth is our ability to attend to tasks at hand
  • We are able to deal with 7 +/- 2 bits of information
  • The Zeigarnik effect reduces our bandwidth
  • Increasing cognitive load decreases bandwidth and increases errors
  • Distractions are common source of increased cognitive load
  • Expertise results in heuristics that allow us to bypass our working memory





Further reading


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  1. Pingback: LITFL Review 219 | LITFL: Life in the Fast Lane Medical Blog

  2. Derek Louey

    Many of our quality interventions focus on increasing signal when our efforts should be to reduce noise.


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