Inhibitory mechanisms in Down syndrome: Is there a specific or general deficit? Erika Borella a, *, Barbara Carretti a , Silvia Lanfranchi b a Department of General Psychology, University of Padova, Italy b Department of Developmental Psychology, University of Padova, Italy 1. Introduction Several studies have examined executive functioning, i.e. the higher-order control mechanisms that can regulate human behavior and cognition (e.g. Stuss & Alexander, 2000), in individuals with Down syndrome (DS). They have generally shown an impairment in individuals with DS in tasks assessing set-shifting, sustained attention, planning, inhibition/preservation and working memory (Lanfranchi, Jerman, Dal Pont, Alberti, & Vianello, 2010; Rowe, Lavender, & Turk, 2006). Few studies have concentrated on inhibitory mechanisms in individuals with DS, however, although inhibition is a mechanism (or rather a family of functions) with a central role in contributing to efficient cognitive performance (Garavan, Ross, & Stein, 1999). Some such studies analyzed the efficacy of intentional motor inhibition in DS using variations of the ‘‘go/no-go’’ task (where participants are required to respond – go – when a particular stimulus is presented, and not to respond – no-go – when another stimulus appears, or when the former is presented in conjunction with another stimulus, such as a tone), and of the ‘‘stop-signal’’ paradigm (where participants are asked to stop an action or thought in response to the appearance of a specific stimulus (Logan, 1985); see Nigg, 2000 for a review). Using the go/no-go task, Pennington, Moon, Edgin, Stedron, and Nadel (2003) found no differences in terms of accuracy between 11- and 19-year-old individuals with DS and a group of typically developing (TD) children of the same mental age. Rowe et al. (2006) used a motor perseveration task to compare the performance of a group of adults with DS (23–40-years Research in Developmental Disabilities 34 (2013) 65–71 A R T I C L E I N F O Article history: Received 13 June 2012 Accepted 17 July 2012 Available online 30 August 2012 Keywords: Down syndrome Cognitive inhibition Working memory A B S T R A C T The cognitive profile of individuals with Down syndrome (DS) is known to be characterized by an impaired executive functioning, but inhibition-related processes have not been extensively examined in this setting. The aim of the present study was to investigate whether individuals with DS have any specific or general deficit in inhibitory processes. Tasks measuring prepotent response inhibition (the animal Stroop test), proactive interference (proactive interference task and intrusion errors), and response to distracters (directed forgetting task) were administered together with a working memory test to 19 individuals with DS and 19 typically developing (TD) children matched for mental age. Confirming previous findings, our results showed that the DS group performed less well in a verbal working memory task than the TD children. Analyzing our findings for the three inhibitory tasks yielded a picture of the DS children having a generalized difficulty in suppressing information that is irrelevant, or no longer relevant, to the goals of the task. These results suggest that DS is related not to specific, but rather to generalized inhibitory difficulties. ß 2012 Elsevier Ltd. All rights reserved. * Corresponding author at: Department of General Psychology, Via Venezia 8, 35131 Padova, Italy. Tel.: +39 049 8276035; fax: +39 049 8276600. E-mail address: erika.borella@unipd.it (E. Borella). Contents lists available at SciVerse ScienceDirect Research in Developmental Disabilities 0891-4222/$ – see front matter ß 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ridd.2012.07.017