Chromostereopsis is the effect of different colors clashing to confuse the depth of the objects. So, for example, blue and red stripes will confuse the eye and mess with perception. This has a material impact on designers and artists.
A simple thing like a good morning or good night message has been shown to trigger feel-good chemicals in the brain. So if you want to make someone feel good, just send them a message at the start or end of a day.
