What would be interesting would be to see the pixel size of text on different users’ computers. I suspect that a lot of people leave the text on ‘medium’ or increase it to ‘large’ because web authors set a font-size that is substantially smaller than default.

For example - when I read use it, I reduce the text to ’small’, because when the text is at a natural size, IE’s default is larger than I find comfortable. But on other sites, such as a list apart, the designer has specified body text at 0.8em (a decision I strongly disagreed with at the time of the redesign, and still do), which means I have to increase the text size from my preferred size to make the tiny text legible.

This becomes a vicious circle. Designers like tiny text, we all know that. Which means that people have to bump up the text size on their computers. Designers find out that a lot of people are using medium/large text so reduce the text size even more so that at those settings it looks like how they want it. So users have to enlarge the text even further.

So without knowing the pixel height of the letters on people’s screens, we don’t know to what extent they are (i) choosing a preferred setting, based on natural font size, (ii) compensating for designers who think everyone wants to read microscopic text, or (iii) blissfully unaware that they are even able to change the displayed font size…