What impact can the use of warm colours, such as red, orange and yellow, have on a drawing or painting?

Warm colours are often used to connote positive emotions, for example yellow can be associated with happiness and red with love and affection. However, depending on the meaning of the piece they can also be associated with darker themes, for instance red can be used to indicate danger. As well as depending on the meaning of a piece, the impact of warm colours also depends on what other colours have been used and in what amount. Warm colours, especially when bright and vibrant, contrast greatly with darker, cooler colours because they are opposite them on the colour wheel. This can make a piece stand out more and engage the viewer. Warmer colours often bring components towards the foreground of an image, while cooler colours such as blue and green anchors them into the background, however this isn't always necessarily true.