Working memory and the brain’s limits

By Dan Peterson

The impact of working memory on sport performance doesn’t get talked about too often, but its importance can’t be underestimated.  Working memory is different from both long and short term memory, it is the ability to hold and juggle things in your head, and the ability shift attention between them as you solve a problem or deal with a situation.

Working memory is what allows us to drive a car while we simultaneously monitor our speed, pay attention to the road ahead, talk to the person in the passenger seat, check our rearview mirror every few seconds, etc.  Similarly, it’s also what allows a basketball player to dribble the ball, pay attention to his defender and one or two teammates at a time, all while evaluating whether he can or should shoot the ball.  It’s a huge component of intelligence and high-level performance, no matter the task.

And new research findings from Earl Miller and Timothy Buschman out of MIT have clarified a lot about how working memory works at both a practical and neural level, and could have an immediate impact on several fields, sports among them.  Miller and Buschman tested the working memory of monkeys (which, sort of amazingly, have the same working memory capacity as humans) via a visual working memory task in which 2-5 objects were presented across both the right and left visual fields, followed by a blank screen, and then followed by the same image with a slight change to one of the objects. The aim was to measure when the change could or could not be detected.  What the researchers found was that the distrubution of the objects across the visual field mattered as much as the number of objects presented in total.  When one side of the visual field was overloaded, the brain simply wasn’t able to process the information; it was lost immediately, like it never even made it to working memory.

From the researchers:

“But surprisingly, we found that monkeys, and by extension humans, do not have a general capacity in the brain,” says Miller. “Rather, they have two independent, smaller capacities in the right and left halves of the visual space. It was as if two separate brains – the two cerebral hemispheres – were looking at different halves of visual space.”

To clarify, these findings indicate that our working memory capacity doesn’t act like a single resource pool that we can draw from.  Rather, it is like two separate, smaller pools, and that these pools are associated with information presented in our right and left visual fields.  You can pay attention to around four different things at once, but only if they are distributed evenly in your visual field.  Our brains can’t handle overload on one side or another, if one side gets overloaded, that information just gets lost, the other side can’t pick up the slack.  For a long time, there has been debate over whether working memory works like a pool, or like a series of slots.  The researchers think that their results prove that it is a little bit of both.

“Our study shows that both the slot and pool models are true,” says Miller. “The two hemispheres of the visual brain work like slots, but within each slot, it’s a pool. We also found that the bottleneck is not in the remembering, it is in the perceiving.” That is, when the capacity for each slot is exceeded, the information does not get encoded very well….

What is so interesting about these findings is that they can be used to great effect right away.  It is rare that neuroscientific research is so immediately and broadly applicable.

“The fact that we have different capacities in each hemisphere implies that we should present information in a way that does not overtax one hemisphere while under-taxing the other,” explains Buschman. “For example, heads-up displays (transparent projections of information that a driver or pilot would normally need to look down at the dashboard to see) show a lot of data. Our results suggest that you want to put that information evenly on both sides of the visual field to maximize the amount of information that gets into the brain.”

The application to sports can be immediate as well.  Let’s think about a football quarterback.  A quarterback with an average working memory capacity can accurately keep track of and make good decisions about four receivers at a time.  This research implies that receiver sets that space receivers more evenly across the quarterback’s visual field could optimize his working memory capacity, and possibly make it easier for him to find the open man or make good decisions.

On the other side of the ball, blitzing defenses might use the strategy of overloading one side of the quarterback’s visual field, with the knowledge that it will be nearly impossible for the quarterback to keep track of each defender, due to the limitations of working memory and perception.

This knowledge has huge potential to inform play design in football, basketball, or any other sport where manipulating player position could be used to create an advantage based on exploiting the weaknesses of our brain’s working memory capacity.  It is just one more example of how neuroscience is opening doors for the thinking coach and athlete to gain an advantage.

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