Massive fast-food chains like McDonald’s, Wendy’s, and In-N-Out Burger all share a similar color scheme on their logos: red, orange, and yellow. No, it is not just because the sincerest form of flattery is imitation, there is an actual scientific reason behind it. Certain colors evoke certain human responses. For instance, the color blue generally makes people feel calm. Yellow and orange, two of the most common colors on fast food logos, make people feel hungrier than they actually are. Combine that with the color red, which invokes passionate emotion in people, and you get passionately hungry customers.