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After reading the question What is the impact of showing the amount of unattended notifications to the user, it occurred to me that many notifications (certainly not all) are red, two examples being inbox messages here (SE) and any notification on Facebook. Whereas, some notifications on StackExchange are in light blue (eg for badges and edits). Green is often associated with check-mark notifications (such as on my AVG virus scan and as the accepted answer here).

(Anecdotal side note: I sometimes get the feeling "oh what have I done this time" when the red notification shows here and a "oh goody!" when the blue shows up).

There are many examples of different colours being used for different types of notifications. What is the psychological basis of these notification colours?

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up vote 1 down vote accepted

It is all about attention and reaction time: Information are coded in visual, aural and tactile channel. Here you have primer of visual coding. Visual coding could be signs or text.

You have shorter time of reaction to primary colors (red yellow blue) and there is some kind of international standard which determine meaning of colors ( red-stop, green - walk... etc...) That is the reason why red.

I recomend you that you read some text in visual sensory perception, measuring time reaction, and some book of ergonomics psychology.

EDIT: Literature:

EDIT2: Here are lot about reaction time:

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Thank you for this, do you have references to add to this answer? Also, green is a primary colour for emitted light (yellow is a primary for pigments). – user3554 Sep 17 '13 at 9:31
i could make some search when i come home. this information i recalled from lectures in ergonomics. thank you for info about cones. – ICanFeelIt Sep 17 '13 at 9:37
Any links would be most appreciated - particularly about your first paragraph and reaction times, these intrigue me greatly. – user3554 Sep 17 '13 at 9:39
I'm must say I'm a bit surprised by this question. To me it seems common knowledge that (a) red is the most alarm color (see traffic signs, traffic lights, brake lights on cars) and (b) while red is not an exact complement of blue it is the one color on the other side of the color circle that has the most attention value (see a). Blue is for non-urgent notifications, red is urgent. Why is it urgent on FB? Because FB is all about being excited to get many friend requests and stuff, while SE is relaxed and rational (so no need to scream "Notification!" with a red color). – what Sep 17 '13 at 12:32
@what thank you, but I was after references to the psychology behind this (which I have received), not 'it is common knowledge that..'. In some cultures red is considered as 'alarm' etc. – user3554 Sep 17 '13 at 20:48

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