About a month ago, I had a difficult conversation with my daughter. Her year in college had not gone particularly well and I asked her what she was going to do differently next year. One of the first things she was going to do, she said, was to clean up her student room. It was just too cluttered to concentrate. Not only 20-year-old students hypothesize about the effects of environments on thought; social psychologists do too. My daughter’s hypothesis is straightforward: messy environments are distracting . The social psychologists’ hypotheses take us a little further afield. For example: Messy environments promote stereotyping . The paper describing research into this hypothesis was co-authored by Diederik Stapel and has been retracted. Another hypothesis is that messy environments promote a longing for simplicity . The paper describing research into this hypothesis was co-authored by Dirk Smeesters and has been retracted . Now there is a new study on messiness. It is abo...