1.1. The hue-heat-hypothesis
Starting point of the hue-heat-hypothesis is the idea of psychological
distinction between “warm colours” and “cool colours”.
Blue, green and purple colours are considered to be cool, while yellowish
and reddish hues are seen as warm [58]. In everyday life,the
association between those colours and thermal temperature may
be found for example, in the coding for taps, where red symbols
refer to warm, blue symbols to cold water.
The distinction between warm and cool colours may be found
since the 18th century [26], and was intensively elaborated in
Goethe’s colour theory [27]. This divide between warm and cool
colours has also been found in colour naming patterns