Red and blue are also thought by psychologists to improve brain performance and receptivity to advertising. The 2009 study in Science supports this idea. It also suggests nuances that world leaders and presidential candidates might want to know about, assuming one buys into the notion that presidential messages and speeches are essentially a form of advertising.
The study found that red is the most effective at enhancing our attention to detail, while blue is best at boosting our ability to think creatively.
"Previous research linked blue and red to enhanced cognitive performance, but disagreed on which provides the greatest boost," said study leader Juliet Zhu of the University of British Columbia. "It really depends on the nature of the task."
Zhu and colleagues tracked the performance of more than 600 people on cognitive tasks that required either creativity or attention to detail. Most experiments were conducted on computers with a screen that was red, blue or white.
Red boosted performance on detail-oriented tasks such as memory retrieval and proofreading up to 31 percent more than blue. For brainstorming and other creative tasks, blue cues prompted participants to produce twice as many creative outputs compared with red cues.
Why? Look around.
"Thanks to stop signs, emergency vehicles and teachers' red pens, we associate red with danger, mistakes and caution," Zhu said. "The avoidance motivation, or heightened state, that red activates makes us vigilant and thus helps us perform tasks where careful attention is required to produce a right or wrong answer."
And the value of blue?
"Through associations with the sky, the ocean and water, most people associate blue with openness, peace and tranquility," says Zhu, who conducted the research with UBC doctoral candidate Ravi Mehta. "The benign cues make people feel safe about being creative and exploratory. Not surprisingly it is people's favorite color."