Journal of Abnormal Psychology 1992, Vol. 101, No. 4, 682-689 In the public domain Attentional Cues in Chronic Schizophrenia: Abnormal Disengagement of Attention Paul G. Nestor, Steven E Faux, Robert W McCarley, Virginia Penhune, Martha E. Shenton, and Seth Pollak Department of Psychiatry, Harvard Medical School, Brockton Department of Veterans Affairs Medical Center and Massachusetts Mental Health Center Stephen E Sands University of Texas at El Paso Posner's (1980) reaction time (RT) paradigm was used to examine the engagement and disengage- ment operations of visual selective attention in patients with schizophrenia. In the 1st experiment, 14 medicated, chronic schizophrenic subjects (diagnosed by criteria of the Diagnostic and Statisti- cal Manual of Mental Disorders', American Psychiatric Association, 1987) and 15 age-matched normal control subjects made a speeded response to a target preceded by a valid, an invalid, or no cue. Control subjects showed the expected advantage and disadvantage in RT for valid and invalid cues, which suggests intact engagement and disengagement operations. For schizophrenic patients, valid cues also enhanced RT, but invalid cues did not slow RT. Similar results were found in the 2nd experiment. The failure of unpredictable, invalid cues to inhibit RT in chronic schizophrenia may be related to an abnormality in the disengagement operation of selective attention. A disorder in attention has long been thought to underlie the information-processing disturbance of schizophrenia. Much of this research has often been hampered by both the absence of objective techniques to isolate attentional processes and the lack of specific biological models of attentional processes. Re- cently, however, the study of the various aspects of attention has become increasingly sophisticated at both the psychological and biological levels (Corbetta, Miezin, Dobmeyer, Shulman, & Petersen, 1990; Parasuraman & Davies, 1984; Posner & Peter- son, 1990; H. Spitzer, Desimone, & Moran, 1988), the influence of which has spawned the burgeoning field of cognitive neuro- science (Churchland & Sejnowski, 1988). Central to this enter- prise is the development of simple experimental paradigms that are capable of disentangling specific, elemental attentional processes and linking them to discrete neural systems. Posner and his colleagues (Posner, 1980; Posner, Snyder, & Davidson, 1980) have developed a widely used experimental paradigm that has produced a fairly clear-cut set of data about the underlying neural structures of selective visual attention. In this paradigm, subjects look at a central fixation point that is flanked by two small squares. A target appears in one of the two squares, and the subject's task is to respond as quickly as possible to the target, usually by pressing a button. On most trials the target is preceded by a visual cue that indicates the likely location of the target. On 80% of the cued trials, the cue is Preparation for this article was supported in part by the Department of Veteran Affairs Medical Research Service and by National Institute of Mental Health Grant 40799. Correspondence concerning this article should be addressed to Rob- ert W McCarley, Brockton Department of Veterans Affairs Medical Center, Department of Psychiatry 116A, 940 Belmont Street, Brock- ton, Massachusetts 02401. valid, correctly indicating the location of the target, and on 20% of the cued trials, the cue is invalid or incorrect, and the target appears in the opposite location. Reaction times (RTs) are compared with baseline trials in which the target is preceded by no cue, and such a comparison provides a means to conduct a cost-benefit analysis of performance. Studies with this proce- dure have consistently demonstrated benefit, or faster perfor- mance, for validly cued trials and cost, or slower performance, for invalidly cued trials (Jonides & Mack, 1984; Posner et al, 1980). Such findings held whether the cue was presented in peripheral vision, such as by brightening one of the two squares, or at central fixation, such as by displaying an arrow (Posner, 1980). The paradigm thus distinguishes two specific components of selective attention, namely, engagement (benefit) and disengage- ment (cost). Studies have suggested that lesions of the posterior parietal lobe affect the disengagement operation, as demon- strated by increased cost for invalid cues (Posner, Walker, Frie- drich, & Rafal, 1984), and those of the thalamus are associated with a deficit in the engagement operation, as demonstrated by reduced benefit for valid cues (Rafal & Posner, 1987). A mark- edly different pattern of results, characterized by normal bene- fit for valid cues but no cost for invalid cues, has been obtained in idiopathic Parkinson's patients (Wright, Burns, Geffen, & Geffen, 1990) and in young normal subjects who were adminis- tered catecholamine (dopamine) antagonists (Clark, Geffen, & Geffen, 1989). In both studies the investigators interpreted the absence of cost for invalid cues in terms of an abnormality in the disengagement operation, but unlike parietal lesion pa- tients, who showed excessively slow disengagement, the sub- jects in Wright et al.'s and Clark et al.'s studies showed exces- sively fast disengagement. That is, invalid cues did not slow RT. Posner, Early, Reiman, Pardo, and Dhawan (1988) were the 682