[kqr]

> red means cancel/go back/stop/error. This is something that was learned, not something that was known by instinct.

Well...[1][2] There are some precedents for red being a no-go colour even in nature. Which is likely why we use it as a stop colour. It would be interesting if someone knows of a significant number of cultures that use it as a "go ahead" colour. I mean, the samples are probably skewed because everyone has been a colony these days but still.

[1]: http://www.noaa.gov/features/resources_0109/images/fire1.jpg [2]: http://museumvictoria.com.au/spidersparlour/images/en000008....

[marcosdumay]

Transit lights were standardized during the XX century. You won't find a place that uses them differently.

But there are cultures where red means good things.