The purpose of our research was to investigate the effect of colour on cognitive processing styles in social decision-making situations. The present research investigated the effect of colour on estimating the price of a gift for a social target. Two colours, blue and red, were provided as environmental cues, and the motivation for a decision was manipulated, by varying the target person's level of attractiveness in a presentation slide during a gift-purchasing simulation. A blue background with low motivation resulted in the anchoring effect, meaning that participants used heuristic processing. However, for a blue background with high motivation and red backgrounds with both high and low motivational levels, participants were not influenced by any anchoring effect. The results indicated that the effect of colour on cognitive style interacted with the motivational level, the attractiveness of the photo target. The theoretical implications, evolutionary explanation, and ideas for further research are also discussed.