Contents lists available at ScienceDirect Cognition journal homepage: www.elsevier.com/locate/cognit Original Articles Working memory training and perceptual discrimination training impact overlapping and distinct neurocognitive processes: Evidence from event- related potentials and transfer of training gains Thomas J. Covey ⁎ , Janet L. Shucard, David W. Shucard Division of Cognitive and Behavioral Neurosciences, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, 114 Sherman Hall Annex, South Campus, Buffalo, NY 14214, United States Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, 114 Sherman Hall Annex, South Campus, Buffalo, NY 14214, United States Neuroscience Program, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, 114 Sherman Hall Annex, South Campus, Buffalo, NY 14214, United States ARTICLE INFO Keywords: N-back Working memory training Perceptual discrimination training N2 P3 ABSTRACT There is emerging evidence that working memory (WM) can potentially be enhanced via targeted training protocols. However, the differential effects of targeted training of WM vs. training of general attentional pro- cesses on distinct neurocognitive mechanisms is not well understood. In the present study, we compared adaptive n-back WM training to an adaptive visual search training task that targeted perceptual discrimination, in the absence of demands on WM. The search task was closely matched to the n-back task on difficulty and participant engagement. The training duration for both protocols was 20 sessions over approximately 4 weeks. Before and after training, young adult participants were tested on a battery of cognitive tasks to examine transfer of training gains to untrained tests of WM, processing speed, cognitive control, and fluid intelligence. Event- related brain potential (ERP) measures obtained during a Letter 3-Back task and a Search task were examined to determine the neural processes that were affected by each training protocol. Both groups improved on measures of cognitive control and fluid intelligence at post- compared to pretest. However, n-back training resulted in more pronounced transfer effects to tasks involving WM compared to search training. With respect to ERPs, both groups exhibited enhancement of P3 amplitude following training, but distinct changes in neural responses were also observed for the two training protocols. The search training group exhibited earlier ERP latencies at post- compared to pretest on the Search task, indicating generalized improvement in processing speed. The n-back group exhibited a pronounced enhancement and earlier latency of the N2 ERP component on the Letter 3-back task, following training. Given the theoretical underpinnings of the N2, this finding was interpreted as an en- hancement of conflict monitoring and sequential mismatch identification. The findings provide evidence that n- back training enhances distinct neural processes underlying executive aspects of WM. 1. Introduction Working memory (WM) is generally characterized as the short term maintenance and manipulation of information for the purpose of completing task-specific goals. While its precise structure is not uni- versally agreed upon, a popular view is that there are multiple com- ponent processes engaged during WM, including distinct buffers that serve to store different types of sensory information, as well as an overarching central executive system that selectively manipulates in- formation within those stores (aka “supervisory attentional system”; Baddeley & Hitch, 1974; Repovs & Baddeley, 2006). More recently, WM is suggested to be a limited resource system that involves the activation and maintenance of sensory information in distributed cortical regions, with executive control over the information that is maintained in WM exerted primarily via prefrontal cortex (D’Esposito & Postle, 2015). WM is thought to be central to cognition and have a broad relationship with multiple cognitive domains. For example, individual differences in WM functioning have been associated with variation in higher level rea- soning and problem solving (i.e., fluid intelligence, Gf; Conway, Cowan, Bunting, Therriault, & Minkoff, 2002; Conway, Kane, & Engle, 2003; https://doi.org/10.1016/j.cognition.2018.08.012 Received 16 March 2017; Received in revised form 6 August 2018; Accepted 21 August 2018 ⁎ Corresponding author at: Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, The State University of New York, Department of Neurology, Division of Cognitive and Behavioral Neurosciences, Sherman Hall Annex, Room 114, Buffalo, NY 14214, United States. E-mail address: tjcovey@buffalo.edu (T.J. Covey). Cognition 182 (2019) 50–72 0010-0277/ © 2018 Elsevier B.V. All rights reserved. T