Short-Term Memory and Web Usability

Individual Differences

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 background knowledge. Most likely, you're in this elite group. And, worse yet, so are many other members of your Internet team. (And the rest are definitely in the top 25%, which is also much better than average users.)

That your own short-term memory may hold two more items than most users' might not seem like a lot. But if your website blocks off short-term memory slots by requiring users to remember extraneous information, a little extra STM capacity can make all the difference in usability. You still have enough spare slots to think about the product line, but if your customers exhaust their brain capacity, they'll find your site very frustrating indeed.

Even though it's a bad course title, it's a good overall mnemonic to design for cavemen and their literal-minded and limited-capacity brains. After all, your paying customers are only one step out of the cave.

Learn More:

Short-Term Memory and Web Usability (Jakob Nielsen's Alertbox)