"Reaction [beta]"
Fire engines are supposed to be red, right? 12 Apr 2007
On Tuesday we blogged the results of a study that found that green text on a yellow background is better than good old black-and-white when it comes to web readability. Since then we've been digging around for supporting evidence and came across the work of Stephen S. Solomon and James G. King.
Having studied psychological research on human visual and auditory perception, Solomon and King learnt that the colour-transmitting cones in our eyes don't work well in the dark, making some colours - particularly greenish-yellows - easier for us to see under dim lighting conditions. The two researchers used their knowledge of these perceptual differences to analyse accident data from the Dallas Fire Department and made some interesting discoveries:
"In the 1970's and early 1980's, the City of Dallas started replacing its all-red fire vehicles with lime-yellow fire vehicles with white upper cabs. After the early 1980's, the fire department bought red vehicles with white cabs. During their four year study published in 1995, Solomon and King found that the risk of a visibility-related, multiple-vehicle accident may be as much as three times greater for red or red/white fire pumpers compared to lime-yellow/white pumpers. The results also show that when lime-yellow/white fire emergency vehicles are involved in an accident, the likelihood of injury or towaway damage is less than for red or red/white vehicles involved in an accident. An earlier study by Solomon involving nine cities and 750,000 fire-vehicle trips found that lime-yellow fire pumpers were half as likely as red fire pumpers to be involved in intersection accidents."
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5 comments so far
David Simmons 12 Apr 2007 01:27 PM
That's amazing data - so how come the red colored trucks live on?
Stephen L 12 Apr 2007 07:54 PM
David: The report at the end of etre's link suggests that the red might be on the way out:
"Applying the findings of human factors and ergonomic research, the Federal Aviation Administration has converted their aircraft rescue and fire-fighting fleets to lime-yellow. Many communities are also switching to lime-yellow fire vehicles, resulting in fewer accidents and lives saved."
Paul 13 Apr 2007 09:28 AM
I wonder how much of this is just because the trucks are "different". London buses are also typically red - and by and large I pay them little attention. I do notice every time the new number 8 goes by my window near Bank station, though. (It's a horrible creamy mustard colour). Do I notice it because it's yellow-ish? Or because it's new / different?
Michael Zuschlag 17 Apr 2007 10:11 PM
I don't see the relevance of this to last Tuesday’s post concerning screen font. The Solomon and King work is evidence that greenish-yellow contrasts more than red against the urban landscape. That doesn’t tell us anything about the contrast (let alone readability) of green against yellow. Hill’s green on yellow has a relatively medium level of contrast, a Luv distance of 86 assuming a sRGB model (black on white is 116). This is something Hill well understood, which led to her second experiment with black on grays, where again a medium contrast (92) performed best with her task. If you want to look for more evidence, try more of Hill’s work: http://hubel.sfasu.edu/research/spie99.html. Here, she finds somewhat conflicting evidence with her earlier work, with colors combinations of medium (black on gray) and high contrast (black on yellow) performing better than medium-high contrast (black on blue). It still looks too early to tell what’s going on.
Michael Zuschlag 17 Apr 2007 10:56 PM
D'oh! I said before the contrast of white on black is 116 in Luv space. Of course, it's actually 100. The 86 is correct. The 92 should be 76. I think I got it right now. The substance of what I was trying to say is still correct.