Facilitation and interference of selective attention in schizophrenia

Theories of attentional impairment in schizophrenia predict excessive interference in selective attention tasks, such as the Stroop task, where subjects must name the color of words which spell colors different than the to-be-named-color. However, a recent study actually found greater facilitation, i.e. improved color-naming time when the color-word agrees with the to-be-named color, and near-normal interference in schizophrenic patients when compared to normal controls. To evaluate these findings, we studied 12 schizophrenic patients (10 on neuroleptics), and 12 age- and gender-matched, healthy subjects in a trial-by-trial Stroop task. The patients exhibited significantly greater facilitation on the Stroop task compared to the normal controls (81 and 12 ms, respectively). Interference effects were not significantly greater for the schizophrenic patients. These findings suggest a need for more work to investigate why schizophrenic patients appear to benefit from the facilitation condition more than normal controls do.