Human and Computer Interaction
Short-Term Memory and Web Usability
by JAKOB NIELSEN on December 7, 2009
* Human Computer Interaction
Summary: The human brain is not optimized for the abstract thinking and data memorization that websites often demand. Many usability guidelines are dictated by cognitive limitations.
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. Lest designers forget how easily users forget, let's review why our brains seem to be so weak.
Human beings are remarkably good at hunting the woolly mammoth. Our ancestors did fine ...view middle of the document...
It definitely wouldn't activate concepts related to improving your site's business performance. In contrast, the title we ultimately chose includes the word "customers," which primes the memory in a more appropriate way, attracts more clicks, and puts users in a business-oriented mindset.
Designing for Brainpower Limitations
When it comes to abstract thinking, humans have extremely limited brainpower. For example, short-term memory famously holds only about 7 chunks of information, and these fade from your brain in about 20 seconds.
It's a common misconception that limited short-term memory implies that menus should be similarly limited to 7 items. It is fine to have longer menus (if needed), because users don't have to memorize the full list of menu items. The entire idea of a menu is to rely on recognition rather than recall (one of the basic 10 heuristics for user interface design). There are many other usability issues in menu design, and shorter menus are certainly faster to scan. But if you make a menu too short, the choices become overly abstract and obscure.
Short-term memory limitations dictate a whole range of other Web design guidelines:
* 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 color 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. If you require users to move back and forth between separate product pages to deduce differences, they'll get confused — particularly if the pages present the information in an inconsistent format.
* Instead of using coupon codes, encode offers in special links embedded in your email newsletters and automatically transfer the coupon to the user's shopping cart. This has two benefits:
* The computer carries the burden of remembering the obscure code and applying it at the correct time.
* It eliminates the "enter coupon code" field, which scares away shoppers who don't have coupons (and who refuse to pay full price when the checkout flow blatantly signals that other users are getting a better deal).
* 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. (See ourApplication Usability course for more on help and user assistance.)
Although the average human brain is better equipped for mammoth hunting than using websites, we're not all average. In fact, there are huge 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...