Visual Turn

Working memory: "the bottleneck is not in the remembering, it is in the perceiving"

That quote is probably the most important sentence I have read in a year.

Working memory refers to the number of things a person can actively hold in memory at once, such as numbers or colors. Most people can remember about four things at once, and some can remember more.

MIT neuroscientists have found that the limitations on working memory do not come from limitations on remembering. Instead they come from how many things can be accurately perceived at once. We bump up against limits in visual perception in the process of encoding things into working memory even before we try to recall those things.

It gets better. The study also found that we do not have a working memory, but actually have working memories — two of them — one in each of the right and left hemispheres of the brain. The researchers concluded that the typical limit of four items in working memory at once was actually a limit of two items in the working memory of each of the two hemispheres.

“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,” said Timothy Buschman, the researcher who conducted the study.

I’ve been aware of the limits of working memory, and how this impacts the design of learning content in instructional technology, from research by Ruth Colvin Clark and Richard E. Mayer. The two ideas from Buschman’s study, though, raise some interesting additional questions.

What does it mean to balance the cognitive load between the left and right hemispheres? How should the visual design of instructional content reflect this idea? What could be done in content presentation that might increase the capacity or accuracy for visual perception in each hemisphere? How does pedagogy change if we recognize that perception is more important than recall in the capacity of working memory?

We already know that content delivered simultaneously through multiple modalities — such as visual and auditory — can increase the capacity of working memory. Does working memory related to other modalities also function as a dual system? Could this mean we actually have four (or more) distinct working memories that operate as an integrated system?

Education focuses so heavily on recall and pays so little attention to perception. This suggests that we really ought to consider whether we have things backwards.

— Visual Turn