The performance of creative writers on the Goldstein-Sheerer Object-Sorting Test was compared with that of admitted manic and schizophrenic patients. Writers and manics tended to show more behavioral and conceptual overinclusion, but the writers showed substantially more richness and the manics more idiosyncratic thinking. Schizophrenics tended to be underinclusive rather than overinclusive and showed less richness and bizarreness than the writers and manics.
These data imply that the conceptual style of writers may resemble mania more than schizophrenia and that, if overinclusiveness is an index of thought disorder, manics may have a more florid thought disorder than schizophrenics.
Andreasen NJC, Powers PS. Creativity and PsychosisAn Examination of Conceptual Style. Arch Gen Psychiatry. 1975;32(1):70-73. doi:10.1001/archpsyc.1975.01760190072008