Lukas Mathis has written a short but insightful piece on the idea that simple designs for icons and action related UI makes more sense. His conclusions also reminded me of some of the studies done on faces and body shape as it relates to attractiveness. The retention of juvenile characteristics or Neoteny suggests that the retaining the basic look or shape of the child or immature version has the outcome of making it more attractive to our visual brains.
A great example of this is the evolution of the Mickey Mouse character. In 1978, Stephen Jay Gould theorized that Walt Disney and his animators gradually discovered what it took evolutionary psychologists decades to prove: that baby-like features and proportions elicit an “automatic surge of disarming tenderness” in adults.
Simple UI or icons offer more inferred information as opposed to prescriptive. The simpler the icons the more likely we are to throw them into a general category instead of wondering which action or quality to ascribe to them. As Lukas Mathis points out, “People are confused by symbols if they have too many or too few details. They will recognize UI elements which are somewhere in the middle.”