Different colors have different physiological effects on humans. Color also influences the way people see and process information. It can improve peoples' ability to remember both words and pictures. In the study, participants looked at 48 photographs, half in color and half in black and white. It wasn't just any color that strengthened people's memory, but only the colors inherent to the scenes the photos depicted. The results of that and other studies suggest that color is a vital factor in retention.