What’s also interesting is the ‘genericisation’ of some colours – as exemplified by the red and orange for fast food example. 

One can see why some companies have pursued the holy grail of trade mark protection for a single colour.  The main problem for them, though, is that colour is usually not distintive per se, and so they are left to prove factual distinctiveness, at least to some degree – the natural defence to this from competitors is the very thing which will drive the colour to being generic and the thing that the first move would like to stop – adoption of the same colour.

All seems ripe for a game theory analysis…

There is an interesting site that talks of the psychology of colo(u)r at http://psychology.about.com/od/sensationandperception/a/colorpsych.htm

None of this is new of course – my Food Marketing 101 lectures in 1973 gave me notes on what colours are best used with food, and those that should be avoided at all costs.  Notable amongst the “avoid” list was black!  How times change!  Today black is endemic in the supermarket wherever a brand-owner wants to convey “sophistication” you will find black!  I guess a key insight is that none of this psychology is static … choose your colour with care ‘cos it could come to mean something you don’t want to be associated with!