Deficits on two continuous performance test versions and the forced-choice span of apprehension task, which are potential vulnerability factors for schizophrenic disorders, were examined in relationship to particular symptoms of schizophrenic disorders, with emphasis on hypothesized relationships to formal thought disorder and negative symptoms. These interrelationships were determined concurrently within a group of 40 schizophrenic patients at an inpatient point. In addition, 32 of these patients were retested at a stabilized outpatient point to address the extent to which continued attentional deficits were associated with specific symptomatology during the hospitalized period. Signal-discrimination deficits on the three tasks were consistently associated with inpatient negative symptoms of schizophrenia as measured by the Anergia factor of the Brief Psychiatric Rating Scale (BPRS), across both the inpatient and outpatient assessments. The outpatient signal-discrimination deficits also showed significant, but less consistent, correlations with inpatient schizophrenic modes of thinking measured by the Rorschach Thought Disorder Index and with formal thought disorder measured by the BPRS Conceptual Disorganization rating. In contrast, no relationship with inpatient hallucinations or delusions was found. Combined with previous findings from high-risk samples, these results are consistent with the view that signal-discrimination deficits in situations demanding high levels of effortful processing are enduring vulnerability factors for schizophrenic negative symptoms and possibly for certain schizophrenic forms of thought disorder.