Reading has arguably the longest and richest history of any domain for scientifically considering the impact of technology on the user. From the 1920s to the 1950s, Miles Tinker 1963] and other researchers ran hundreds of user tests that examined the effects of different fonts and text layout variables, such as the amount of vertical space between each line of text (called leading). Their research focused on user performance, and reading speed was the favoured measure. They charted the effect of the manipulated variables on reading speed, looking for the point at which their participants...