by Ian Matheson and Dr. Nancy Hutchinson
A great deal of research has emerged in the last few decades that has been focused on a system known as working memory. Learning disabilities (LDs) are often characterized by problems in the working memory system (Hallahan, Pullen, & Ward, 2013). This system is reputed to be responsible for managing incoming sensory information and facilitating the manipulation of information that is already stored in memory. While neuroscientists interested in working memory have examined the structure of this system, cognitive psychologists have focused their attention on what this system is used for and have developed models to outline the functions of working memory (Repovs & Baddeley, 2006). Working memory is generally viewed as an executive function system, where executive functions are responsible for all cognitive processes used for higher level cognition (Ilkowska & Engle, 2010). Higher level cognition includes the control of one’s attention, the use of cognitive strategies, and actively searching long-term memory, among other processes.
Though a number of models of working memory have been proposed, a model created by Baddeley and Hitch (1974) has received perhaps the greatest deal of empirical support. The model includes a central executive that controls other slave systems known as the phonological loop, the visuo-spatial sketchpad, and the episodic buffer. The central executive was presented as a system that focuses, divides, and switches attention between the information being held by the slave systems in order to manipulate or operate on the information while it is maintained in working memory. The phonological loop was presented as a system that is responsible for storing and maintaining phonological information, while the visuo-spatial sketchpad was presented as a system responsible for the storage and maintenance of both visual and spatial information. The episodic buffer, added later to the model (Baddeley, 2000), combines visual and auditory elements to create episodes, and can be understood as one’s imagination where scenes or episodes are created in one’s head. The episodic buffer is also used as a space for considering outcomes and planning behaviour (Baddeley, 2006), and has been classified as the workspace wherein the manipulation of information takes place (Hofmann, Friese, Schmeichel, & Baddeley, 2011).
Cognitive load is a topic that is linked with working memory; it refers to the limited capacity of our working memory system and how different types of tasks vary in the amount of attention required to be successfully carried out. Sweller (1988) introduced cognitive load theory, which distinguishes between three types of loads – intrinsic, extrinsic, and germane. Intrinsic load refers to the inherent complexity of a task, and extraneous load refers to the elements related to the presentation of information for a task that have the potential to overload the task. Germane load refers to the load devoted to the processing or understanding of a task. An example of each type of load can be illustrated by a student learning the names of planets in our solar system. The intrinsic load is the load devoted to the amount of information that is to be learned (number of planets), and the germane load is made up of load devoted to the processing of the information that is to be learned. The extrinsic load is made up of the environment and conditions within which the new material is being learned – this can include the noise level, what else is going on in the classroom, etc. Ideally, an educator would reduce the extraneous load as much as possible so that the cognitive load is mostly germane – in other words the majority of the student’s energy and attention should be on processing the new information. While intrinsic load cannot be manipulated, instructors aim to limit extraneous load and promote germane load. In his theory, Sweller (1988) suggests that the way information is presented can influence its load, and as a result influence whether or not an individual retains the information or becomes overloaded and does not retain it.
The Importance of Working Memory
Working memory is considered to be a strong predictor of both mathematical (Toll, Van der Ven, Kroesbergen, & Van Luit, 2011) and reading difficulties (Horowitz-Kraus, 2014), and therefore it is considered to be a good basis for intervention to improve performance. The development of the working memory system underlies performance in both math and reading (Jerman, Reynolds, & Swanson, 2012). Researchers have found differences between individuals with and without math difficulties in spatial aspects of working memory (Mammarella, Lucangeli, & Cornoldi, 2010; Passolunghi & Mammarella, 2012), as well as between individuals with and without reading difficulties in the efficiency of encoding and rehearsal mechanisms (Oyler, Obrzut, & Asbjornsen, 2012) – both of which involve the working memory system. Given the problems that individuals with LDs often experience with the working memory system (Hallahan, Pullen, & Ward, 2013), it is important for educators to plan and implement lessons that reduce the germane and extraneous load (De Weerdt, Desoete, & Roeyers, 2012).
When it comes to interventions aimed at improving working memory (and reducing the cognitive load) for individuals with LDs, there are a few main approaches that are used. Researchers have focussed on the explicit teaching of strategies that individuals can use to reduce the germane load of tasks, and therefore reduce the load on working memory. Other research has been conducted that examines the capacity of working memory, and the potential for this system to be improved or “trained” (e.g., Melby-Lervag & Hulme, 2013). Finally, there are accommodations that educators can make for students with LDs that reduce the extraneous load in tasks at school.
Promoting the Germane Load
Cognitive strategy instruction involves teaching processes that individuals can select and use strategically, based on the task, to help promote and manage the germane load (Wong, Harris, Graham, & Butler, 2003). There are a number of empirically supported strategies that can be taught to individuals (Wendling & Mather, 2008), as well as several methods of implementing cognitive strategy instruction (Wong et al., 2003).
Mnemonics is a strategy used as a memory aid that can involve acronyms, acrostics, or rhyming for the purpose of remembering a more sophisticated sequence. An example of an acronym is the use of HOMES to remember the great lakes (Huron, Ontario, Michigan, Erie, and Superior), which takes away the need to remember each lake separately. Another example is the use of BEDMAS to remember the order of operations in mathematics (Brackets, Exponents, Division, Multiplication, Addition, and Subtraction). There is empirical support for the use of this cognitive strategy to promote and manage the germane load of a task (Wolfe, 2001).
Elaboration is a strategy that involves thinking deeply about the information that is to be retained or learned (Squire & Schacter, 2003). An individual may use an organizer to make connections between the new information and their prior knowledge about the subject – elaboration can involve individuals asking themselves questions about the new information and how it fits into their existing knowledge. Engaging more deeply with information naturally promotes germane load as a student is devoting more attention and energy into processing the new information.
Visual Representation involves connecting verbal information to visual cues. Two examples are the method of Loci, where an individual visualizes ‘walking’ through an area with objects that are to be remembered, and the peg word method, where an individual associates items that are to be remembered with numbers visualizing the items relating to each respective number. This strategy is empirically supported for individuals with LDs (Greenleaf & Wells-Papanek, 2003), and helps students manage the processing of information using strategies, thus promoting and helping with the management of the germane load.
Overlearning is the practicing of a skill after it has been mastered by an individual (Squire & Schacter, 2003). This strategy can increasingly promote and help with the management of the germane load of a task as it becomes a more automatic exercise for the individual.
Rehearsal is a common empirically supported strategy forremembering information (Parente & Herrmann, 1996). Rehearsal involves practice that is distributed over a period of time, for varying amounts of time, and with intervening tasks between practice sessions.
Chunking is a strategy used for increasing the amount of information that can be retained in memory. By pairing or associating items into groups, one can remember greater amounts of information. One example can be grouping a ten-digit phone number into area code, prefix, and line number to reduce the items from ten to three. Chunking is an empirically supported memory strategy that is helpful for individuals with LDs (Hardiman, 2003).
Each of these examples can be used in instruction to aid individuals with LDs to prmote and help the student manage the germane load and therefore reduce the load on working memory. Perhaps more importantly, educators should model how to use or construct each type of strategy, as well as when to use them, so that individuals with LDs can use each strategy in appropriate places to improve the efficiency of their working memory system and increase their learning and retention as a result.
Self-Regulated Strategy Development (SRSD)
Harris and Graham (1996) proposed a model for cognitive strategy instruction known as SRSD that has garnered strong empirical support (Harris, Santangelo, & Graham, 2010). This model addresses the cognitive, motivational, and academic characteristics of students, and can be used effectively with students with LDs in all types of classrooms. For a more detailed explanation of this strategy click here.
Cognitive Strategy Instruction in Writing (CSIW)
Another model that has received empirical support (Englert et al., 1991, 1992) and can be used with students with LDs is the CSIW. In this approach, “think sheets” are used to support students during all stages of the writing process (planning, organizing, writing, editing, and revising) (Wong et al., 2003). These sheets provide prompts for students during each stage of the writing process, and are used in conjunction with modelling, and support from educators that is gradually reduced as the student internalizes the processes. For example, the organizing phase of the think sheet would provide prompts that have to do with what resources are needed and what steps are involved in the writing process. In providing a physical extension of student thinking, less demand is placed on the working memory system as students no longer need to recall and maintain the stages of the writing process in their working memory throughout the task.
Strategic Content Learning (SCL)
One other model that can be used for cognitive strategy instruction specifically for adolescents with LDs is the SCL model (Butler, 1995). This approach focuses on students’ developing their own strategies for learning rather than being explicitly taught strategies by educators (Wong et al., 2003). Students are guided by educators to identify strategies, identify their strengths and weaknesses, and evaluate their own learning through prompting. As a result, students develop individualized strategies and feel more responsible for their own performance, which can influence their confidence in using cognitive strategies going forward. The use of strategies aids the processing of information, and therefore decreases demands on working memory.
Each method offers a unique approach for cognitive strategy instruction, though each need not be used in isolation. Educators can make decisions about which method to use or how to combine methods based on the needs of the student as well as the nature of the task or strategies.
The Capacity of Working Memory
While there is empirical support for the teaching of strategies to individuals with LDs to decrease the cognitive load of tasks, another approach is to focus on the process itself by training working memory directly to improve it (Klingberg et al., 2005). The idea that working memory can increase in capacity has received some empirical support (e.g., Mahncke, Connor, et al., 2006). There has been some criticism of research with significant findings about increases in working memory capacity as a result of training, since the effects may be inflated due to increased practice of a task rather than due to an actual change in working memory capacity (Shipstead, Redick, & Engle, 2012).
Melby-Lervag and Hulme (2013) suggested that working memory training programs should not be used as treatment programs for individuals with cognitive disorders or as interventions for improving individuals’ general cognitive skills, based on the findings of a meta-analysis. While working memory may be a system that is relied on heavily when one is learning a new skill such as reading or algebra, it does not take the place of explicit instruction of how to perform these skills. In studies that reported a significant change in working memory, this change was limited to tasks that were similar to the task used in the training, and therefore these findings may reflect improvement due to practice rather than a change in working memory capacity. If change in capacity is indeed possible, it would be more likely to occur in children, as this population has a greater potential for plasticity than older populations (Sprenger et al., 2013)
Research in working memory capacity has also included the examination of individual differences in students, such as affect or mood. In a 2013 study by Yang, Yang, and Isen, the effects of positive affect on working memory were examined with undergraduate students. Participants in the positive affect group performed significantly better than their peers in the neutral affect group on the working memory task. A separate study by Carpenter et al. (2013) had the same finding that positive affect had a positive influence on working memory, this time with adults.
To account for the relationship between affect and working memory, several theories have been proposed. The dopamine hypothesis (Ashby, Isen, & Turken, 1999) states that working memory performance should improve with positive affect based on the boost of this neurotransmitter. The broaden-and-build theory (Fredrickson, 2001) states that positive affect opens individuals up to a wider range of thoughts, actions, and strategies. It is also possible that individuals who are in a better mood feel more obligated to give their best effort if the educator has created the conditions that put them in a good mood in the first place.
These studies suggest that the presence of mild positive affect seems to be related to increases in working memory in both younger adults and older adults. It should be made clear that these are performance increases, and they do not necessarily reflect changes in capacity.
Reducing the Extraneous Load
There are a number of accommodations that educators can make to reduce the extraneous load of tasks in order to support individuals with LDs (Harwell & Jackson, 2008). Accommodations can be grouped into instructional, environmental, and structural.
Instructional accommodations are changes that educators can make to their methods of delivering instruction. One example is providing models, steps, or a list of strategies (on their desks) that students can use for common tasks to reduce their reliance on their working memory system when trying to remember what strategy to use in which situation. Another example is to provide students with a recording device that allows them to play back the newly presented information as many times as they require for processing information, reducing the cognitive load associated with trying to understand the information in real time.
Environmental accommodations are changes that can be made to the physical learning environment. One example could be to provide white noise such as a fan or light instrumental music during work periods that could reduce the impact of distracting noises around the classroom that could capture the attention of students with LDs and make it more difficult for them to focus on the task.
Assessment accommodations are changes that can be made that are specific to tasks that are meant to assess skills. Given that some individuals have difficulties with reading, writing, and mathematics, both extra time and scribing can reduce the germane load associated with processing information for an assessment and can, as a result, allow the individual to focus more on the skill that is being assessed rather than the associated skills that may be difficult for them
It is important to remember that while educators can use strategies to reduce the load on the working memory systems of individuals with LDs, the context and process of using various strategies warrants attention in order to teach individuals with LDs how and when to use them independently. There are a number of strategies that can be used for cognitive strategy instruction, as well as a number of methods for instructing students how and when to use strategies. While it may presently be unclear whether or not working memory capacity can grow and change, research suggests that factors such as mood can influence the efficiency of the working memory system. Educators can make a number of empirically supported accommodations to their teaching, the environment, and their assessment practices to reduce the cognitive load associated with tasks and make it less likely that the working memory systems of individuals with LDs will be overloaded.
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Ian Matheson is entering his second year in the PhD program in Education at Queen's University with a focus in Learning and Cognition. Ian has spent the last two years working as an occasional teacher with the Limestone District School Board where he is certified with the OCT as an elementary school teacher. He is currently involved with the Continuing Teacher Education Centre at Queen's University where he is an instructor for an Additional Qualifications course.
Nancy L. Hutchinson is a professor of Cognitive Studies in the Faculty of Education at Queen’s University. Her research has focused on teaching students with learning disabilities (e.g., math and career development) and on enhancing workplace learning and co-operative education for students with disabilities and those at risk of dropping out of school. In the past five years, in addition to her research on transition out of school, Nancy has worked with a collaborative research group involving researchers from Ontario, Quebec, and Nova Scotia on transition into school of children with severe disabilities. She teaches courses on inclusive education in the preservice teacher education program as well as doctoral seminars on social cognition and master’s courses on topics including learning disabilities, inclusion, and qualitative research. She has published six editions of a textbook on teaching students with disabilities in the regular classroom and two editions of a companion casebook.