Cognitive inhibition and schizophrenic symptom subgroups.

Subgroups of patients with schizophrenia were examined in relation to repetition and semantic priming under conditions in which the prime stimulus was to be either attended to or ignored (unattended). Attended conditions normally would produce positive priming; and unattended conditions, negative priming (i.e., a delayed reaction resulting from inhibition of target information previously presented as to-be-ignored stimulus). Cluster analysis of participants' ratings on the Schedule for the Assessment of Positive Symptoms and the Schedule for the Assessment of Negative Symptoms revealed three subgroups that aligned broadly previous research citing with disorganization, reality distortion, and psychomotor poverty syndromes, and a fourth episodic subgroup. The Disorganization, Reality Distortion, and Episodic subgroups were associated with reduced, indeed reversed, negative priming in unattended priming conditions, whereas the Psychomotor Poverty subgroup exhibited the usual negative priming effect. Participants in the former three subgroups also exhibited reversed positive priming for the repetition condition, while the Psychomotor Poverty group displayed the expected positive priming effect. These results indicate that weakening of inhibitory processes may underlie both the reality distortion and disorganization dimensions of positive schizophrenic symptomatology, including the latent presence of these symptoms. In contrast, negative symptoms contributing to the psychomotor poverty dimension of schizophrenia are not linked to reduced inhibition. The association of positive symptom subgroups with reversed positive priming suggested that, for these participants, stimuli and task differences have an impact on the preattentive activation of information underlying such priming. It is proposed that a "reduced inhibition" model of schizophrenic symptomatology may need to be extended to account for influences on preattentive processing.