The British Psychological Society Research Bulletin this week has an article entitled New evidence that the "Chaotic Mind" of ADHD brings creative advantages based on a paper Thinking Outside the Box: Unconstrained Creative Generation in Adults with Attention Deficit Hyperactive Disorder. Students (some with ADHD) were asked to draw alien fruits that did not resemble any fruits that they knew - and the above was the result.
While the size and nature of the group tested may make generalizations about the average ADHD suffer unreliable my reaction is that the experiment confirms how difficult it is for the average person to think outside the box formed by their experiences.