Intact and impaired cognitive-control processes in schizophrenia Edward E. Smith a,b,c, ⁎, Teal S. Eich c , Deniz Cebenoyan c , Chariklia Malapani a,b a Department of Psychiatry, Columbia University, United States b Department of Cognitive Neuroscience, New York State Psychiatric Institute, United States c Department of Psychology, Columbia University, United States article info abstract Article history: Received 4 September 2010 Received in revised form 20 November 2010 Accepted 25 November 2010 Available online 5 January 2011 Deficits of cognitive-control in schizophrenia have been assumed to result from a single impairment that leads to widespread consequences. Contrary to this view, we hypothesized that different control processes operate at different stages of processing, and that only some of these processes may be impaired. We employed two selection tasks to test the hypothesis that patients with schizophrenia have deficits in selecting information in working memory (WM), but not in selecting perceptual information. In the “Ignore” task, which fosters perceptual selection, participants saw a cue to remember either red or blue words, followed by a memory- set (2 red, 2 blue), a brief delay, and then a probe. The “Suppress” task was similar, except the memory-set came before the instruction-cue, and hence selection had to occur in WM. We recorded reaction time and percentage errors for positive probes (“Valid”), and two kinds of negative probes, those that were supposed to have been dropped from WM (“Lures”) and those that had not appeared in the memory-set (“Controls”). Compared to healthy controls, patients were impaired in the Suppress but not the Ignore task. This dissociation implies that there are two different selection mechanisms. © 2010 Elsevier B.V. All rights reserved. Keywords: Working-memory Selection Inhibition Cognitive-control Suppression 1. Introduction 1.1. Objectives Among the most frequently noted cognitive deficits in patients with schizophrenia are those involving cognitive- control (Barch, 2005; Barch et al., 2004; Bellgrove et al., 2006; Snitz et al., 2006). Discussions of these deficits often assume that there is a single attentional/inhibitory deficit that leads to widespread consequences, as in the “Context model” of cognitive-control (Barch, 2005; Cohen and Servan-Schreiber, 1992; Minzenberg et al., 2009). In this model, a deficit in a unitary attention system, mediated by the dorsolateral– prefrontal cortex (DLPFC), is responsible for deficits in many tasks, including the Stroop, the AX-CPT, and language produc- tion tasks. In contrast, following the lead of recent work in cognitive neuroscience (Friedman and Miyake, 2004; Nee et al., 2007), we propose that there are qualitatively different kinds of control processes, only some of which are impaired in schizophrenia. We provide evidence for this hypothesis by showing that schizophrenic patients are relatively intact in selecting perceptual information before entry into working memory (WM), but impaired in selecting information once in WM. 1.2. Background Nee and Jonides (2008, 2009) recently developed a pair of tasks called “Ignore” and “Suppress” that target control processes at different stages: perceptual encoding vs. mainte- nance in WM. Both tasks are variants of the Item-Recognition task (Sternberg, 1966), in which a memory-set containing a few items is presented, followed by a brief delay, and then a probe to which the participant responds positively if it matches an item in the memory-set and negatively otherwise. In both Schizophrenia Research 126 (2011) 132–137 ⁎ Corresponding author. Department of Cognitive Neuroscience, New York State Psychiatric Institute, 1051 Riverside Drive, Unit #50, New York, NY 10032, United States. Tel.: +1 212 543 5716; fax: +1 212 543 5472. E-mail address: eesmith@psych.columbia.edu (E.E. Smith). 0920-9964/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2010.11.022 Contents lists available at ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres