Objective:“Michael’s game” (MG) is a card game targeting the ability to generate
alternative hypotheses to explain a given experience. The main objective was to evaluate
the effect of MG on delusional conviction as measured by the primary study outcome: the
change in scores on the conviction subscale of the Peters delusions inventory (PDI-21).
Other variables of interest were the change in scores on the distress and preoccupation
subscales of the PDI-21, the brief psychiatric rating scale, the Beck cognitive insight
scale, and belief flexibility assessed with the Maudsley assessment of delusions schedule
(MADS).