On 17/02/13 10:48, Philippe Verdy wrote:
I was not citing empirical results but things that are regulated by legislation. And your existing empirical results are just nfomal tests ignoring important parts of the population of drivers, notably: - those driving by night : the effet of some visual defects like asygmatism, which is only partially corrected and which can only be compensated by sufficient contrast (lowercase letters do not contrast enough, because their strokes are too near of each other) - the effect of presbytia on vision of aging population : here again the size of letters does matter (look at those phones sold to ages people: most of them are completely unable to use modern smartphones for example, they are unreadable even with the best visual correction), even if they wear "progressive glasses", they have a reduced angle of good focusing, and if letters are too small, they need to stop looking at the road to fix the displays on roads for longer time. Every people above the age of 40 starts suffering this visual defficiency where adaptation to vision depth is more difficult and longer. larger letters that can be read easily even before there's a full focus helps reducing the adaptation time. - also by night, the effect of tireness also slows down the visual adaptation and reduuces the angle of good focusing. In all these cases, you need less density of strokes, and capital letters are better constrasting. Of course there are other factors like the effective constrast of colors used on those displays, the negative impact of too narrow fonts, insufficient intercharacter advance gaps, and insufficient boldness. Note that a perfect 10/10 vision (or better) is not mandatory to drive, there are legal minimums where people with only 8/10 can legally drive (and other visual defects are NOT tested at all, notably the various forms of color blindness (mot cases being full or partial deuteranopia, affecting about 1 on 6-8 male human in Europe, depending on test methods : this is definitely not a small population).
Here are some excellent articles about the evidence-based approach that led to the development of current road signage in the United States.
http://www.nytimes.com/2007/08/12/magazine/12fonts-t.html?pagewanted=1&_r=0 and this, on research on the legibility of mixed/lower case vs. ALL CAPS: http://www.microsoft.com/typography/ctfonts/WordRecognition.aspx Regarding Clearview and older drivers, this: http://deldot.gov/information/pubs_forms/manuals/de_mutcd/pdf/20080731061923147.pdf is particularly interesting: the take-home quote is this:
The greatest improvement in legibility distance afforded by Clearview was realized by older drivers when viewed under headlamp illumination during nighttime conditions (an increase in legibility distance of between 6.0 percent and 6.8 percent)
-- Neil