Research Article Letter and Colour Matching Tasks: Parametric Measures of Developmental Working Memory Capacity Tamara L. Powell, 1,2 Marie Arsalidou, 1,3,4 Vanessa M. Vogan, 1,5 and Margot J. Taylor 1,6 1 Department of Diagnostic Imaging and Neurosciences and Mental Health Programme, Research Institute, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, ON, Canada M5G 1X8 2 Department of Psychology and Language Sciences, University College London, 26 Bedford Way, London WC1H 0AP, UK 3 Department of Psychology, National Research University Higher School of Economics, Myasnitskaya Street 20, Moscow 101000, Russia 4 Department of Psychology, Faculty of Health, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3 5 Applied Psychology and Human Development, Ontario Institute for Studies in Education, University of Toronto, 252 Bloor Street W., Toronto, ON, Canada M5S 1V6 6 Department of Psychology, University of Toronto, 27 King’s College Circle, Toronto, ON, Canada M5S 1A1 Correspondence should be addressed to Tamara L. Powell; tamarapowell6@gmail.com Received 22 July 2014; Revised 9 November 2014; Accepted 11 November 2014; Published 30 November 2014 Academic Editor: Andrew N. Meltzof Copyright © 2014 Tamara L. Powell et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. We investigated the mediating role of interference in developmental assessments of working memory (WM) capacity across childhood, adolescence, and young adulthood. One hundred and forty-two participants completed two versions of visuospatial (colour matching task, CMT) and verbal (letter matching task, LMT) WM tasks, which systematically varied cognitive load in a high and low interference condition. Results showed similar developmental trajectories across high interference contexts (CMT- and LMT-Complex) and divergent developmental growth patterns across low interference contexts (CMT- and LMT-Simple). Performance on tasks requiring greater cognitive control was in closer agreement with developmental predictions relative to simple recall guided tasks that rely solely on the storage components of WM. hese indings suggest that developmental WM capacity, as measured by the CMT and LMT paradigms, can be better quantiied using high interference contexts, in both content domains, and demonstrate steady increases in WM through to mid-adolescence. 1. Introduction Working memory (WM) refers to a cognitive system that temporarily maintains and manipulates information, which is crucial for performance on a wide range of cognitive tasks. WM plays an important role in reasoning and learning [1], language comprehension [2], and executive function [3, 4] and is a central component of intelligent behaviour [5]. Despite considerable research devoted to examining individual diferences in WM, there is not yet any consensus in the literature as to the storage limits or developmental trajectories expected in either the visual or the verbal WM domain [6]. Discrepancies in developmental estimates may be due, in part, to inconsistencies in ways of operationally deining, assessing, and measuring cognitive demand in tasks of varying complexity [7]. he present study addresses this issue by highlighting the mediating role controlled interfer- ence plays in the measurement of WM across development. A main challenge in extracting a general trajectory of WM across development has been the limitations of narrow age ranges and the relative absence of adolescents and young adults within the developmental literature. A great deal of the behavioural research on WM has come from studies of children in their preschool or early school-age years (e.g., [8– 10]), but less in later childhood. his is unfortunate given the increasing evidence for protracted development of the frontal lobes and the functions they support well into adult- hood [11]. Although some recent studies have explored this Hindawi Publishing Corporation Child Development Research Volume 2014, Article ID 961781, 9 pages http://dx.doi.org/10.1155/2014/961781