It's true, I am a Baby Boomer and that means I have less than a year before I am eligible for Social Security. That puts me at the cusp of being old-aged rather than middle-aged.
This reality made it inevitable that seeing the title of Jakob Nielsen's latest Alertbox resulted in clicking the link to read the article Middle-Aged Users' Declining Web Performance (Jakob Nielsen's Alertbox)
First of all, Nielsen classifies middle age as between 25 and 60. Take that Gens X and Y! On the downside, I fall into his "senior citizen" group. But, so does he!
A study by Nielsen found that "Between the ages of 25 and 60, the time users need to complete website tasks increases by 0.8% per year."
Why? The biggest factor, Nielsen says, "is that older users need more time to understand pages, scan the text, and extract the information."
Okay, our eye site is declining, but is Nielsen saying we get stupid as we age? No. The age at which participants started using the Web impacted the outcome in his study; longer experience slows declining performance. And he predicts as today's young people age, their decline in Web performance will settle in around 5% per year.
Nielsen does conclude from his study that we need not worry about special usability guidelines for 40- or 50-year olds; the statistical performance difference is not significant.
Young children, teenagers, and senior citizens still require special consideration, however, and you can link to Nielsen's conclusions about how to design for these groups from within this article. Guess I better go read that senior citizen piece.