In previous work using the Stroop task to examine cognitive function in schizophrenia, we have suggested that reaction time (RT) facilitation and error interference should be more sensitive measures of cognitive function than RT interference. We examined this hypothesis in 36 DSM-IV schizophrenia and schizoaffective patients, who performed both the Stroop and the Speaking Span, a measure of verbal working memory. The results supported our hypotheses, demonstrating that RT facilitation and error interference were associated more strongly with working memory performance than RT interference. The robust correlations between these measures of selective attention and Speaking Span performance has implications for understanding the nature and selectivity of cognitive dysfunction in schizophrenia. We present several different hypotheses that may explain this relationship, including: (1) a generalized deficit; (2) a common cognitive disturbance; and (3) a common neurobiological dysfunction.