Or consider this 2009 experiment, published in Science. The psychologists, at the University of British Columbia, were interested in looking at how the color of interior walls influence the imagination. They recruited six hundred subjects, most of them undergraduates, and had them perform a variety of basic cognitive tests displayed against red, blue or neutral colored backgrounds.

The differences were striking. When people took tests in the red condition – they were surrounded by walls the color of a stop sign – they were much better at skills that required accuracy and attention to detail, such as catching spelling mistakes or keeping random numbers in short-term memory. According to the scientists, this is because people automatically associate red with danger, which makes them more alert and aware.

The color blue, however, carried a completely different set of psychological benefits. While people in the blue group performed worse on short-term memory tasks, they did far better on those requiring some imagination, such as coming up with creative uses for a brick or designing a children’s toy out of simple geometric shapes. In fact, subjects in the blue condition generated twice as many “creative outputs” as subjects in the red condition. That’s right: the color of a wall doubled our imaginative power.