The Role of Language in the Development of Cognitive Flexibility

Executive functioning is a fundamental part of everyday life, but develops slowly across childhood. One essential aspect of executive functioning is cognitive flexibility, the ability to update behavior and thought based on the needs of a constantly changing environment. This study investigated the role of language in the development of cognitive flexibility, which has shown contradictory effects in prior work. For example, labels impaired 3-year-olds’ cognitive flexibility as measured in an instructed cardsorting task (Yerys & Munakata, 2006), but improved 4-year-olds’ cognitive flexibility as measured in an internally-driven card-sorting task (Jacques, Zelazo, Lourenco, & Sutherland, 2007). This study tested whether these opposing findings might be explained by age differences or task differences, by testing 3-year-olds in the Flexible Item Selection Task with and without labels. Children in the condition with explicit labels performed worse than children in the condition with ambiguous labels. These results suggest that explicit labels may impair cognitive flexibility in 3-year-olds, regardless of task, suggesting that age determines whether labels will help or hurt children’s cognitive flexibility. Theoretical implications and future directions are discussed. LANGUAGE ON COGNITIVE FLEXIBILITY 3 The role of language in the development of cognitive flexibility Executive function refers to a complex network of decision-making and behavioral systems that are vital to success in daily life. Aspects of executive function include planning, inhibiting a dominant response, and directing attention (Zelazo, Muller, Frye, & Marcovitch, 2003). Without executive functions, behavior would be based primarily on stored habits, rather than being sensitive to changing circumstances in the environment. Cognitive flexibility, one component of executive functioning, refers to the ability to understand multiple and sometimes conflicting perspectives and representations (Jacques & Zelazo, 2005). One example of cognitive flexibility is the ability to view a common object in an untraditional way in order to maximize its use, such as repurposing an empty jelly jar as a water glass. Cognitive flexibility emerges slowly across development. Indeed, children are notoriously habit-driven, and often have difficulty breaking routines and flexibly modifying habits and behaviors. However, over the course of development, children slowly gain the ability to adapt behavior to meet the demands of a changing environment. Nonetheless, certain populations continue to face difficulties with cognitive flexibility even as adults, such as individuals with obsessive-compulsive disorder (Chamberlain, Fineberg, Blackwell, Robbins, & Sahakian, 2006), individuals with eating disorders (Tchanturia, et al., 2004), and individuals with depression (Fossati, Ergis, & Allilaire, 2002). Therefore, an improved understanding of the factors that influence cognitive flexibility is not only a central goal for basic science, but also has implications for the domains of education and mental health across the lifespan. LANGUAGE ON COGNITIVE FLEXIBILITY 4 Many frameworks have been proposed to explain the development of cognitive flexibility, with prominent accounts focusing on the role of attention and representational skills (e.g., Kirkham, Cruess, & Diamond, 2003; Zelazo, 2004; Munakata, 1998). One unifying theme across existing frameworks is the idea that competition between habitbased and flexible representational systems can influence the ability to behave adaptively. Language is one factor that has been studied as a mediator between these two systems, due to its well-established role in the representation of abstract concepts (Deak, 2003; Jacques, et al., 2007). The act of interpreting language involves flexible thought in itself, as this requires selection and encoding of specific information in a shifting environment (Deak, 2003). Furthermore, providing a verbal label to an object, idea, or event enables the flexible manipulation of such representations in working memory (Deak, 2003; Cragg & Nation, 2010; Muller, Zelazo, Lurye, & Libermann, 2008), which is especially important for multi-dimensional representations that can be attended to in different ways. Therefore, the role of language in cognitive flexibility has often been studied in children, especially given that both cognitive flexibility and language skills are simultaneously developing. Labeling is one type of language manipulation that has been employed in cognitive flexibility tasks with children. For example, labeling manipulations have varied the specificity of the label for the first dimension that is presented to children in a sorting task that involves multi-dimensional objects (e.g., from something descriptive, like “these match in color”, to something more ambiguous, like “these match in one way”) before asking children to sort by a second dimension. However, such manipulations have produced contradictory effects. For example, in one study, LANGUAGE ON COGNITIVE FLEXIBILITY 5 descriptive labels impaired cognitive flexibility: 3-year-olds who were provided with explicit labels to explain the rules of the Dimensional Change Card Sort task (DCCS; Zelazo, Frye, & Rapus, 1996), a card-sorting cognitive flexibility task, performed worse when asked to later switch to sorting the same cards by a different dimension, relative to 3-year-olds who were instructed using ambiguous labels (Yerys & Munakata, 2006). In the DCCS, the experimenter provides explicit instructions for how to sort a series of cards (e.g., “In the shape game, trucks go here, and flowers go here”) (Yerys & Munakata, 2006). When using ambiguous labels, the experimenter would inexplicitly instruct how the cards were supposed to be sorted (e.g., “In the sorting game, these go here and these go here”). When asked to then switch to another sorting dimension, 3year-olds performed worse on this task when explicit labels were used. Instructing both ways the participants need to sort the cards makes the DCCS an externally-driven task, because participants are provided with all the necessary to successfully complete the task. One explanation for the performance differences between groups is that when labels are used in externally-driven contexts, activations associated with the first sorting rule are strengthened. This may cause children to fixate on that sorting rule, which could lead to impaired switching when a conflicting sorting rule is externally instructed (Yerys &