Abstract
Centre for Education Statistics and Evaluation (2017). Cognitive load theory: Research that teachers really need to understand. Sidney, Australia: Centre for Education Statistics and Evaluation.
James had received language therapy in kindergarten and first grade because of his multiple morphological errors (errors in tense marking, and use of copulas and auxiliaries). When dismissed from therapy, he was not exhibiting morphological errors in conversation. However, in second grade, in his writing, he frequently omits tense markers. Crystal’s SLP uses themes in her interventions, using several related stories for each theme. When Crystal listens to these stories in therapy sessions while looking at the pictures in the story, she can identify story grammar components and appropriately answer questions about the components. When Crystal listens to the teacher read stories in the classroom, she has difficulty answering similar questions.
How can one explain the differing performance of these students on tasks that appear to require similar skills? The concept of cognitive load may be useful in understanding and responding to these differing performances. Cognitive load theory is a theory of how the human brain learns and stores knowledge. A large number of randomized-controlled studies support cognitive load theory and its implications for teaching practice. Cognitive load research demonstrates that instructional methods are most effective when designed to fit within the known limits of working memory and, therefore, strongly supports explicit, guided models of instruction. This article describes the research on cognitive load theory and what it means for more effective teaching practice. The first part of the article explains how human brains learn according to cognitive load theory. The second part examines the implications of cognitive load theory for teaching practice, and describes some recommendations that are directly transferable to the classroom.
What Is Cognitive Load Theory
Cognitive load theory is built on two assumptions: (a) that there is a limit to how much new information the human brain can process at one time and (b) that there are no known limits to how much stored information can be processed at one time. The aim of cognitive load research is to develop instructional techniques and recommendations that fit within the characteristics of working memory to maximize learning.
Cognitive load theory supports explicit models of instruction. Explicit instruction involves teachers clearly showing students what to do and how to do it, rather than having students discover or construct information for themselves. When using explicit instruction, The teacher decides the learning intentions and success criteria, makes them transparent to the students, demonstrates them by modelling, evaluates if the students understand what they have been told by checking for understanding, and retelling them what they have been told by tying it all together with closure. (Hattie, 2009)
Cognitive load theory emerged from the research on working memory. It is based on theories about how human brains process and store information. These assumptions include the following: Human memory can be divided into working memory and long-term memory, information is stored in the long-term memory in the form of schemas, and processing new information results in cognitive load on working memory, which can affect learning outcomes (Anderson, 1977; Baddeley, 1983).
Working memory is the memory system where small amounts of information are stored for a very short duration (Peterson & Peterson, 1959). It is the limited mental space in which we think. Although research indicates that persons can differ in working memory capacity, the average person can only hold about four chunks of information in their working memory at one time (Cowan, 2001). Long-term memory is the memory system where large amounts of information are stored semipermanently (Tulving, 1972). Cognitive load theory assumes that knowledge is stored in long-term memory in the form of schemas. A schema organizes elements of information, representing knowledge about concepts, objects, and the relationships they have with other objects, situations, events, sequences of events, actions, and sequences of actions. Skilled performance is developed by building ever greater numbers of increasingly complex schemas by combining elements of lower level schemas into higher level schemas. An important process in schema construction is automation, whereby information can be processed automatically with minimal conscious effort. Automaticity occurs after extensive practice (Sweller, van Merrienboer, & Paas, 1998).
Types of Cognitive Load
There are three types of cognitive load: intrinsic, extraneous, and germane load. The three types of cognitive load are generally assumed to be additive—that is, intrinsic load + extraneous load + germane load = total cognitive load. Cognitive overload occurs when the total cognitive load exceeds the working memory capacity of the learner (Gerjets, Scheiter, & Cierniak, 2009).
Intrinsic
Intrinsic cognitive load relates to the inherent difficulty of the subject matter being learned (Sweller, 1994, 2010; Sweller & Chandler, 1994). Intrinsic load is a necessary type of cognitive load. Two factors influence intrinsic cognitive load: the complexity of the material and the prior knowledge of the learner (Sweller, van Merrienboer, & Paas 1998). This means that subject matter that is difficult for a novice may be very easy for an expert. For example, spelling consonant, vowel, consonant (CVC) words would have a high cognitive load for a kindergarten child but not for a fourth-grade child. Intrinsic cognitive load can be altered by instructional techniques that make complex material easier to learn. Intrinsic cognitive load of material can be lowered in three possible ways:
The components of a task can be introduced to the learner in a simple-to-complex order so that the learner does not initially experience the full complexity of the material (van Merrienboer, Kirschner, & Kester, 2003).
A part–whole approach can be used. The individual components of the task are introduced to the learner first, before the integrated task or whole task is introduced (Bannert, 2002; Pollock, Chandler, & Sweller, 2002).
Introduce the task in its full complexity from the beginning, but then direct the attention of the learner to the individual interacting components.
Extraneous
Extraneous cognitive load relates to how the subject matter is taught: “Extraneous cognitive load . . . is not necessary for learning (i.e., schema construction and automation) and can be altered by instructional interventions” (van Merrienboer & Sweller, 2005). Extraneous load is the bad type of cognitive load, because it does not directly contribute to learning. Instructional design will be most effective when it minimizes extraneous load to free up the capacity of working memory. A combination of high intrinsic and high extraneous cognitive load may be fatal to learning because working memory may be substantially exceeded.
Germane
Germane cognitive load refers to the load imposed on the working memory by the process of learning—that is, the process of transferring information into the long-term memory through schema construction. Germane cognitive load can be understood as the good type of cognitive load. Instructional material has maximum effectiveness when it reduces extraneous load (which is not relevant to learning) and increases germane load (which is directly relevant to learning). The combination of decreasing extraneous cognitive load and increasing germane cognitive load involves redirecting attention. Learners must attend to the processes that are relevant to learning (toward the construction of schemas) and must not attend to processes that are not relevant to learning. Intrinsic, extraneous, and germane load are considered to be additive (Paas, Renkl, & Sweller, 2003). Consequently, the approach of decreasing extraneous cognitive load while increasing germane cognitive load will only be effective if the total cognitive load remains within the limits of working memory (Sweller et al., 1998).
Educational Recommendations From Cognitive Load Research
Psychologists and educational researchers have advocated two general approaches to teaching practice: One group believes that people learn best when allowed to discover or construct some or all of the information themselves (e.g., Bruner, 1961; Papert, 1980; Steffe & Gale, 1995). Others believe that learners do best when they are provided with explicit instructional guidance in which teachers clearly show students what to do and how to do it (e.g., Klahr & Nigam, 2004; Mayer, 2004; Rosenshine, 1986). Cognitive load theory provides theoretical and empirical support for the explicit model of instruction.
Research has clearly demonstrated that for novices (virtually all students), direct, explicit instruction is more effective and more efficient than partial guidance. So, when teaching new content and skills to novices, teachers are more effective when they provide explicit guidance accompanied by practice and feedback, not when they require students to discover many aspects of what they must learn (Clark, Kirschner, & Sweller, 2012). Cognitive load theorists do not advocate using all aspects of explicit instruction all the time. They do recognize the need for learners to be given the opportunity to work in groups and solve problems independently; however, they maintain that this should be used as a means for practicing newly learned content and skills, not to discover information themselves.
The following recommendations for teaching arise from cognitive load theory:
The worked example effect. A worked example is a problem that has already been solved for the learner, with every step fully explained and clearly shown. According to cognitive load theory, unguided problem solving places a heavy burden on working memory, inhibiting the ability of the learner to transfer the information into their long-term memory. The learner may effectively solve the problem, but because their working memory was overloaded, they may not recognize and remember the rule that would allow them to quickly solve the same problem again in the future.
The expertise reversal effect. The expertise reversal effect is an important exception to the worked example effect. According to the expertise reversal effect, the heavy use of worked examples becomes less and less effective as learners’ expertise increases, eventually becoming redundant or even counterproductive to learning outcomes (Leslie, Low, Jin, & Sweller, 2012; Pachman, Sweller, & Kalyuga, 2013). This means that some instructional procedures such as worked examples, which assist learning for novices because they reduce cognitive load, are not effective for teaching more expert learners.
The redundancy effect. The “redundancy effect” occurs when learners are presented with additional information that is not directly relevant to learning, or with the same information in multiple forms. An example is a textbook that includes both text and a diagram that needlessly repeat information, or a PowerPoint presentation in which the presenter reads the text presented on the screen. Requiring learners to process redundant information inhibits learning because it overloads working memory. Most people assume that providing learners with additional information is, at worst, harmless and might be beneficial. However, providing unnecessary information can be a major reason for instructional failure (Sweller, 2016).
The split-attention effect. The split-attention effect occurs when learners are required to process two or more sources of information simultaneously to understand the material. This might occur, for example, when a diagram is used to explain a concept, but it cannot be understood without referring to a separate piece of explanatory text. In this instance, the learner is required to hold both sources of information in their working memory at the same time and to mentally integrate the two. This places a high cognitive load on the working memory, interfering with the ability of the learner to transfer the relevant information to their long-term memory. The split-attention effect can be minimized by physically integrating separate sources of information, so that they do not have to be mentally integrated by the learner (Cerpa, Chandler, & Sweller 1996; Owens & Sweller, 2008).
The modality effect. It is also possible to decrease extraneous load on working memory by using more than one mode of communication—both visual and auditory. Working memory can be subdivided into auditory and visual streams (Baddeley, 1983), so presenting information using both auditory and visual working memory can increase working memory capacity (Penney, 1989). For example, when using a diagram and text to explain a concept, the written text can be communicated in spoken form. Using both auditory and visual channels increases the capacity of working memory, and facilitates more effective learning (Tindall-Ford, Chandler, & Sweller, 1997).
Implications
Students with language learning impairments or intellectual impairments have reduced language, cognitive, working memory, and attentional capacities compared with TD students. Many of their skills are less automatic, and when skills are not automatic, they place a heavier cognitive load on the students. The vignettes at the beginning of this review are examples students being overwhelmed by the cognitive load of tasks. Although James could use correct morphology in conversation, writing has increased cognitive loads. He must think about what to write, how to spell and form the letters as he writes. While he is attending to all these elements, he does not have sufficient working memory to also attend to the morphology, which is not fully automatic for him. Crystal’s SLP reduced cognitive load on the therapy activities by using stories on similar themes so that she built background knowledge for Crystal, and she used picture supports to reduce load on auditory memory. Crystal did not have these supports in the classroom. By understanding the effects of cognitive load on students, SLPs can facilitate generalization of skills into classroom activities. SLPs may consider strategies to gradually increase the cognitive load of tasks in therapeutic sessions, and at the same time, they can consult with classroom teachers, alerting them to how cognitive load may affect students’ functioning in the classroom.