Cognitive processing of multidimensional stimuli in schizophrenia: Formal modeling of judgment speed and content

This article presents a formal, mathematical account of relations between r esponse times on simple cognitive tasks and content of complex judgments in volving multiple stimulus dimensions for people with schizophrenia. Changes in multidimensional :judgments were viewed as the result of interference f rom increased stages of encoding with respect to the individual dimensions. Information on dimensional properties encoded earlier in a judgment trial was considered to:be more susceptible to loss over the rest of the trial, b ecause of a larger number of encoding-stages applied to the remaining dimen sional properties. Model predictions were tested with samples-of paranoid a nd nonparanoid schizophrenic participants and controls. Unidimensional enco ding speed was assessed by reaction times in an explicit similarity ratings task, and multidimensional judgment content was assessed by the relative i mportance of different stimulus dimensions to participants' ratings in an i mplicit similarity ratings task. Results support validity of the model.