As usual, Jakob Nielsen's December Alertbox newsletter contains some thought proving stuff.

It is all about short-term memory and web usability. The central thesis is that the brain is not optimised for the abstract thinking and memorising data that web sites often demand.

Most people can't keep much information in their short-term memory. This is especially true when they're bombarded with multiple abstract or unusual pieces of data in rapid succession. To make matters worse, aspects of cognitive ability decline with age.

Nielsen is running a series of workshops (all in the US) on this topic, titled "Usability and the Human Mind: How Your Customers Think." His first thought for the seminar was designing web sites for cavemen but he chicken-out and took the safe naming option instead.

It would seem that our short-term memory famously holds only about 7 chunks of information, and these fade from your brain in about 20 seconds. With this in mind it means that the web site design should ensure that:

  • Response times must be fast enough that users don't forget what they're in the middle of doing while waiting for the next page to load.
  • Change the colour of visited links so that users don't have to remember where they've already clicked.
  • Make it easy to compare products, highlighting the salient differences on both the initial category page and in special comparison views.
  • Offer help and user assistance features in the context where users need them so they don't have to travel to a separate help section and memorize steps before returning to the problem at hand.

To make matters more complicated there are big individual differences in user performance: the top 25% of users are 2.4 times better than the bottom 25%.

At the extreme, only about 4% of the population has enough brainpower to perform complex cognitive tasks such as making high-level inferences using specialized background knowledge.

You can see the problem, if your web designers (and yourself) are in the 4% group you are not going to be aware of the problems of the other 96%.

It looks like a great course. Let’s hope he brings it to Europe.

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