| Disagreement exists concerning the neuropsychological processes underlying category fluency performance in schizophrenics. Some conclude impaired category fluency is due to access/retrieval dysfunction, while others assert disorganization in semantic memory. The present study utilized data from a sample of thirty schizophrenics to explore the relationship of access/retrieval and semantic memory organization to categorical word fluency. Mean choice reaction time (RT) on a lexical decision task and number of inter-node links (Links) generated from Pathfinder network analysis were used as measures of access/retrieval and complexity of semantic memory organization, respectively.; Results revealed that RT and Links were significantly negatively correlated with Fluency. RT and Links were not significantly correlated with one another, and, together, accounted for 30% of the variance in category fluency. RT and Links accounted for approximately equal amounts of the variance in Fluency. These correlations were unrelated to age, sex, education and IQ.; Findings indicate that schizophrenics' verbal output is attributable to both access/retrieval and semantic memory organization factors. Independence of these two predictors suggests that individuals may differ in the underlying nature of fluency problems. The reduction in fluency as the number of semantic links increases may reflect diffusion of cognitive resources or lateral inhibition. The negative association between RT and Fluency could be due to generalized slowness of processing in some schizophrenics or impaired executive/regulatory frontal lobe functions. Thus, as a group, schizophrenics' verbal fluency reflects both access and organizational factors. |
