Marielle's little place on the web

In everyday pyschology, it is well known that too much stress can
cause decline in performance. On the other hand, when people get too
little stimulation, their performance suffers as well. Somewhere in
the middle of this upside down U-shaped curve there is an optimum. This phenomenon was already described in 1908 and is now known as the Yerkes-Dodson law.

Toxicology has its own adaptive response. Biomedicine has preconditioning. A recent article by Calabrese points out that these dose-response phenomena, although known by a multitude of names, share common characteristics. All are biphasic, and the quantitative features are very similar. But they have never really been linked together….

There are probably many more cases like this one. The same phenomenon is discovered independently in different fields of study and because these different fields don’t talk to each other (and they can’t because they use such different terminology) the whole picture is never seen. Multidisciplinarians, or interdisciplinarians cannot solve this, I think we need more true multispecialists.

Your brains like to work, else you get bored, lose attention and start making mistakes. Not too much at a time, though. When cognitive load is too high, you get stressed and start making mistakes as well. Fortunately, we do a pretty good job at giving ourselves just the right amount of brain activity: a phenomenon called load balancing.

Air traffic controllers have been found to give themselves more challenging tasks when air traffic is slow, i.e. optimizing routes for particular kinds of planes while all they have to do is keep them withing certain limits. Senior drivers get into fewer car accidents than one would expect regarding their performance on cognitive tests. They turn off the radio when driving in an unfamiliar environment, and mostly drive in areas they are familiar with and during daytime.

At my temporary job in a coffeehouse, I noticed I am balancing my cognitive load the whole day through (even there!): taking multiple orders from multiple customers or waiting until one is served, using the cash register calculator or doing it by heart, making different espresso-based drinks and keeping wait times as low as possible, etc. Periods of cognitive stress are thus followed by cognitive rest, while it never gets dull.

What does this mean for user interface design? In fact it’s pretty straight-forward. Allow for both easy and cognitively challenging use and let your users do the rest. Sometimes this means allowing different strategies for the same task. Sometimes it means facilitating switching between demanding and less demanding tasks.