"Both individuals who are manic and those who are writers, when evaluated with neuropsychological tests, tend to combine ideas or images in a way that "blurs, broadens, or shifts conceptual boundaries," a type of thinking known as conceptual overinclusiveness. They vary in this from normal subjects and from patients with schizophrenia. Researchers at the University of Iowa, for example, have shown that "both writers and manics tend to sort in large groups, change dimensions while in the process of sorting, arbitrarily change starting points, or use vague distantly related concepts as categorizing principles." The writers are better able than the manics to maintain control over their patterns of thinking, however, and to use "controlled flights of fancy" rather than the more bizarre sorting systems used by the patients."