If you are selling something, you want people to make an instant decision to buy. You don’t really want them to linger, to think about things. If they do that, they can dream up all sorts of objections and therefore decide not to buy. In effect you want to be asking your potential customers “do you want it, or not?”
From a sales perspective, buying really needs to be a “black and white” decision.
However, interesting new research suggests we may need to rethink web design of sales pages. Researchers from the University of Cambridge found that when people were given a dilemma to consider and were “primed” with a black and white image beforehand, their responses tended to be polarised. But without the black and white image being shown in advance of considering the dilemma, then the responses were on a wide spectrum.
The study suggests that when we see in black and white our brain goes into that dual mode of thinking. But when we are looking at things in full colour, our brain is less likely to think in “black and white”.
It implies that you will get higher income from your website if your sales pages are in black and white only, with no colour. You will be forcing people to choose to buy, or not to buy, rather than dither.