Explorations in the Learning Sciences, Instructional Systems and Performance Technologies

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John Sweller Paul Ayres Slava Kalyuga

Cognitive Load Theory

John SwellerUniversity of New South WalesNSW, Australiaj.sweller@unsw.edu.auPaul AyresUniversity of New South WalesNSW, Australiap.ayres@unsw.edu.au

Slava KalyugaUniversity of New South WalesNSW, Australias.kalyuga@unsw.edu.au

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vWithout knowledge of human cognitive processes, instructional design is blind. In the absence of an appropriate framework to suggest instructional techniques, we are likely to have difficulty explaining why instructional procedures do or do not work. Lacking knowledge of human cognition, we would be left with no overarching structure linking disparate instructional processes and guiding procedures. Unless we can appeal to the manner in which human cognitive structures are organised, known as human cognitive architecture, a rational justification for recommending one instructional procedure over another is unlikely to be available. At best, we would be restricted to using narrow, empirical grounds indicating that particular procedures seem to work. We could say instructional procedure A seems better than procedure B but why it works, the conditions under which it works or how we can make it work even better would be rendered unanswerable and mysterious.

In contrast, knowledge of how we learn, think and solve problems human cognitive architecture can provide us with a coherent, unifying base that can be used to generate instructional hypotheses and data. That base can explain why some instructional procedures work while others fail. Seemingly disparate, even contra-dictory data can be explained and reconciled. Most importantly, human cognitive architecture can be used to generate instructional procedures that we otherwise would have considerable difficulty conceiving. The structures that constitute the framework of human cognitive architecture provide an essential prerequisite to instructional design for both researchers and professional educators. Those struc-tures allow us to make sense of instructional design issues. Further, we can use our knowledge of human cognitive architecture to devise instructional theories.

One such theory is cognitive load theory that was explicitly developed as a the-ory of instructional design based on our knowledge of human cognitive architec-ture. Cognitive load theory consists of aspects of human cognitive architecture that are relevant to instruction along with the instructional consequences that flow from the architecture. This book begins by considering categories of knowledge in Part I, human cognitive architecture in Part II, categories of cognitive load in Part III, followed by the instructional effects that flow from these theoretical considerations in Part IV and the conclusions in Part V.

Preface

vi Preface

In recent years, the cognitive architecture used by cognitive load theory has been expanded and anchored within a biological evolutionary framework. Evolution by natural selection has a dual role in cognitive load theory. First, as indicated in Chapter 1 of Part I, we can classify information into two categories. The first category, known as biologically primary knowledge, consists of informa-tion that we have specifically evolved to acquire while the second category, known as biologically secondary knowledge, is information that we need for cultural reasons but have not specifically evolved to acquire. Educational institutions were devised to facilitate the acquisition of biologically secondary information and cognitive load theory deals almost exclusively with that category of information. Chapter 1, by analysing these distinct categories of knowledge, provides an intro-duction to the evolutionary base used by cognitive load theory.

Evolution by natural selection has a second, equally important role in cognitive load theory. Evolutionary theory is usually considered as a biological theory explaining how biological structures, including entire species, arose. That function is, of course, the primary purpose of evolutionary theory. Nevertheless, evolution-ary theory can be considered from an entirely different perspective, as a natural information processing system. By thinking of evolutionary theory in terms of the manner in which information is processed, we can extend evolutionary concepts to other information processing systems such as human cognition.

Biological evolution is not normally considered in information processing terms but there are advantages to thinking of it in this way. When considered as an infor-mation processing system, biological evolution is able to tell us about a particular class of theories, natural information processing theories. These theories tell us how information is processed in nature and evolution by natural selection provides us with the best known and most detailed natural information processing theory. By treating biological evolution as a natural information processing theory, we can throw substantial light on the characteristics of this class of information processing systems because of the large amount of knowledge that we have available to us about biological evolution.

Knowing how natural information processing systems such as biological evolu-tion function is particularly important because human cognition provides another example of a natural information processing system. If we know how biological evolution functions as a natural information processing system, that knowledge can be used to tell us how human cognition functions because human cognition also is a natural information processing system, analogous to evolution by natural selec-tion. Knowing the characteristics of natural information processing systems in general can tell us about some of the central characteristics of human cognition.

Thus, if we know how biological evolution works, it may tell us much about how human cognition works, assuming both are natural information processing systems. If we assume the way we learn, think and solve problems is part of nature because we are part of nature, we need to know how nature learns and solves problems. That aim can be achieved by treating both evolution by natural selection and human cognition as a natural information processing system. Chapters 24 of Part II establish and discuss the suggested analogy between evolution by natural

viiPreface

selection and human cognition. In the process, those chapters provide the cognitive architecture that lies at the heart of cognitive load theory.

Cognitive load theorys emphasis on human cognitive architecture and its evolu-tion is not an end in itself. The ultimate aim of the theory is to use our knowledge of human cognition to provide instructional design principles. The cognitive archi-tecture discussed in Part II tells us that when processing biologically secondary information, human cognition includes a working memory that is limited in capac-ity and duration if dealing with novel information but unlimited in capacity and duration if dealing with familiar information previously stored in a very large long-term memory. Instruction needs to consider the limitations of working memory so that information can be stored effectively in long-term memory. Once appropriate information is stored in long-term memory, the capacity and duration limits of working memory are transformed and indeed, humans are transformed. Tasks that previously were impossible or even inconceivable can become trivially simple. Accordingly, the aim of instructional design is to facilitate the acquisition of knowl-edge in long-term memory via a working memory that is limited in capacity and duration until it is transformed by knowledge held in long-term memory. The char-acteristics of that memory can provide guidelines relevant to designing instruction. The initial process of specifying instructional design principles begins in Part III of this book.

The cognitive load imposed on working memory by various instructional proce-dures originates from either the intrinsic nature of the instructional material, result-ing in an intrinsic cognitive load, or from the manner in which the material is presented and the activities required of learners, resulting in an extraneous cogni-tive load. Chapter 5 in Part III introduces the instructional applications of cognitive load theory by outlining the categories of cognitive load, their interactions and their instructional consequences. Chapter 6 discusses techniques that have been used to measure cognitive load.

The chapters of Part IV discuss the range of instructional effects generated by the theory. Over 25 years, researchers from around the globe have used cognitive load theory to generate a variety of instructional procedures. Those procedures character-istically are tested for effectiveness by comparing them to more traditional methods using randomised, controlled experiments. When the results of such comparisons indicate the superiority of a new procedure over a commonly used procedure, a cognitive load effect is demonstrated. Cognitive load effects provide us with novel instructional guidelines that constitute the ultimate aim of cognitive load theory. These guidelines constitute the major justification for devising cognitive load theory and are discussed in Chapters 717. Each chapter describes one or more of the cognitive load effects generated by the theory with each effect indicating an instruc-tional procedure, tested for effectiveness, and recommended for use. The conclusions of Chapter 18 tie together the various strands of the preceding sections.

Over the two to three decades that cognitive load theory has been used as an instructional theory, it has undergone considerable development and change. In an example of a feedback loop, the changes to cognitive load theory have been driven largely by the instructional effects generated by the theory. Most commonly,

viii Preface

the theory has generated a new instructional procedure at a point in time and that procedure has been demonstrated in a particular curriculum area using a specific set of materials. On occasions, the effect has failed to generalise to a different area and different conditions. Such failures require an explanation and that explanation usu-ally results in both theory development and new instructional effects and proce-dures. In this manner, the edifice that constitutes cognitive load theory has been constructed.

Ultimately, the theory stands or falls according to its ability to generate novel, useful, instructional procedures, a justification common to all instructional theories. We hope cognitive load theory passes this test. The most recent version of the theory, along with the instructional procedures generated by the theory over many years is presented in this book. We begin, in the next chapter, by using evolutionary theory to categorise knowledge.

John Sweller Paul Ayres

Slava Kalyuga

ix

Acknowledgements

There are far too many people who have contributed to cognitive load theory over the years to be able to thank in anything other than general terms. The first group to thank is the army of research students who ultimately did most of the work associated with the theory. Many of those students from around the world have since become highly respected international scholars in their own right. Without them, this book would not have been written. We owe them a debt of gratitude that can never be repaid. One of those ex-students, Elizabeth Owen, carefully read the manuscript and eliminated many of our more clumsy efforts. We thank her for her work, emphasising that any remaining confusions are entirely our responsibility. Another research student, Chee Lee, funded by the Faculty of Arts and Social Sciences at UNSW, did a magnificent job of organising our reference list and assisting with the figures. Her patience knows no bounds!

The empirical work described in this book and largely carried out by research students required the testing of countless students (using those randomised, con-trolled experiments!) in many of the population centres around the world. They deserve a special thank you. We hope that as small compensation, our procedures have assisted them in their studies.

Our many collaborators from around the world have contributed far more to cognitive load theory than we could ever achieve. The theory is theirs, not ours.

Lastly, and most importantly, we would like to thank Susan, Robyn and Marika. They have put up with us and for them, cognitive load theory has been a near lifetime sentence!

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Contents

Part I Preliminaries to Cognitive Load Theory

1 Categories of Knowledge: An Evolutionary Approach ......................... 3

Why Instructional Design Needs to Distinguish Between Biologically Primary and Secondary Knowledge ........................ 4Biologically Primary Knowledge................................................................ 5Biologically Secondary Knowledge............................................................ 6Instructional Consequences ........................................................................ 8

Instructional Consequences Associated with Biologically Primary Knowledge .................................................... 8Instructional Consequences of Biologically Secondary Knowledge ............................................................................. 11

Conclusions ................................................................................................. 13

Part II Human Cognitive Architecture

2 Amassing Information: The Information Store Principle ..................... 17

How Natural Information Processing Systems Store Information .............. 17Evolutionary Biology .............................................................................. 17Human Cognition: Long-Term Memory ................................................. 18

Instructional Implications ........................................................................... 24Conclusions ................................................................................................. 25

3 Acquiring Information: The Borrowing and Reorganising Principle and the Randomness as Genesis Principle ............................. 27

The Borrowing and Reorganising Principle ................................................ 27Biological Evolution ................................................................................ 27Human Cognition .................................................................................... 28Instructional Implications ........................................................................ 31

Conclusions ................................................................................................. 31Randomness as Genesis Principle ............................................................... 32

Biological Evolution ................................................................................ 32

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Human Cognition .................................................................................... 33Instructional Implications ........................................................................ 36

Conclusions ................................................................................................. 37

4 Interacting with the External Environment: The Narrow Limits of Change Principle and the Environmental Organising and Linking Principle ........................................................... 39

Narrow Limits of Change Principle ............................................................ 40Biological Evolution ................................................................................ 40Human Cognition .................................................................................... 41Instructional Implications ........................................................................ 44

Conclusions ................................................................................................. 45The Environmental Organising and Linking Principle ............................... 46

Biological Evolution ................................................................................ 46Human Cognition .................................................................................... 48Instructional Implications ........................................................................ 50

Conclusions ................................................................................................. 50Summary of Structures and Functions of Human Cognitive Architecture ............................................................... 51

Part III Categories of Cognitive Load

5 Intrinsic and Extraneous Cognitive Load ............................................... 57

Additivity of Intrinsic and Extraneous Cognitive Load .............................. 58Element Interactivity ................................................................................... 58Element Interactivity and Intrinsic Cognitive Load .................................... 59

Task Difficulty ......................................................................................... 61Understanding ......................................................................................... 62Altering Intrinsic Cognitive Load ........................................................... 64Relations of Intrinsic Cognitive Load to Human Cognitive Architecture ............................................................................ 65

Element Interactivity and Extraneous Cognitive Load ............................... 66Instructional Implications ........................................................................... 67Conclusions ................................................................................................. 68

6 Measuring Cognitive Load ....................................................................... 71

Indirect Measures of Cognitive Load .......................................................... 71Computational Models ............................................................................ 71Performance During Acquisition............................................................. 72Error Profiles Between Problems ............................................................ 72

Subjective Measures of Cognitive Load ..................................................... 73A Subjective Measure of Mental Effort .................................................. 73A Subjective Measure of Difficulty ......................................................... 73

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Variations in Subjective Ratings .............................................................. 74Consistency of the Subjective Measures ................................................. 74

Efficiency Measures .................................................................................... 75Issues with Calculating Efficiency .......................................................... 77

Measuring Cognitive Load Through a Secondary Task .............................. 77Physiological Measures of Cognitive Load ................................................ 80Measuring the Different Types of Cognitive Load ..................................... 81Summary ..................................................................................................... 85

Part IV Cognitive Load Effects

7 The Goal-Free Effect ................................................................................ 89

Empirical Evidence for the Goal-Free Effect ............................................. 91Alternative Explanations of the Goal-Free Effect ....................................... 93

A Dual-Space Explanation ...................................................................... 93An Attentional Focus Explanation .......................................................... 96A Subjective Measure of Cognitive Load and the Goal-Free Effect ....... 97

Conditions of Applicability......................................................................... 97Instructional Implications ........................................................................... 98Conclusions ................................................................................................. 98

8 The Worked Example and Problem Completion Effects ...................... 99

Basic Empirical Evidence ........................................................................... 100Worked Examples in Mathematics and Related Domains ...................... 100Worked Examples and Ill-Structured Learning Domains ....................... 102Worked Examples in Non-Laboratory-Based Experiments .................... 104Worked Examples and the Alternation Strategy ..................................... 104

The Problem Completion Effect ................................................................. 105Critiques of the Use of Worked Examples .................................................. 106Conditions of Applicability......................................................................... 107Instructional Implications ........................................................................... 108Conclusions ................................................................................................. 108

9 The Split-Attention Effect ........................................................................ 111

Various Categories of the Split-Attention Effect ........................................ 113Worked Examples and the Split-Attention Effect ................................... 114Diagrams and Written Explanations........................................................ 116Multiple Sources of Text ......................................................................... 119More Than Two Sources of Information ................................................. 119Split-Attention While Learning to Use a Computer ................................ 120

Split-Attention and Other Cognitive Load Theory Effects ......................... 122Temporal Split-Attention ............................................................................ 122Alternative Methods to Overcome Split-Attention ..................................... 124

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Directing Attention and the Split-Attention Effect ............................... 124The Pop-Up Alternative to Text Integration ......................................... 125Procedural Information and the Split-Attention Effect ......................... 126Learner Integration of Split-Source Materials ...................................... 126

A Meta-Analysis of the Split-Attention Effect ......................................... 127Conditions of Applicability....................................................................... 127Instructional Implications ......................................................................... 128Conclusions ............................................................................................... 128

10 The Modality Effect ................................................................................ 129

The Effect of Replacing Written with Spoken Text .................................. 130The Modality Effect in Interactive Learning Environments ..................... 132Factors Moderating the Modality Effect ................................................... 134

Levels of Element Interactivity ............................................................. 135Pacing of Presentations ......................................................................... 135An Alternative Explanation for the Reverse Modality Effect ............... 136Reducing Visual Search ........................................................................ 137

Summary of Conditions of Applicability .................................................. 138Instructional Implications ......................................................................... 139Conclusion ................................................................................................ 140

11 The Redundancy Effect .......................................................................... 141

Some Empirical Evidence for the Redundancy Effect .............................. 142The Effect of Simultaneously Presented Written and Spoken Text .......... 144The Redundancy Effect in Second/Foreign Language Learning .............. 146Evidence for the Redundancy Effect in Pre-Cognitive Load Theory Research .............................................................................. 148Factors Moderating the Redundancy Effect .............................................. 149

Independence of Information Sources .................................................. 149Levels of Element Interactivity ............................................................. 150Pacing of Presentations ......................................................................... 150The Length of Instructional Segments .................................................. 151

Summary of Conditions of Applicability .................................................. 152Instructional Implications ......................................................................... 153Conclusions ............................................................................................... 154

12 The Expertise Reversal Effect ................................................................ 155

Some Empirical Evidence for the Expertise Reversal Effect .................... 156Longitudinal Studies ............................................................................. 157Cross-Sectional Studies Using Worked Examples and Other Forms of Guidance ............................................................... 159Expertise Reversal and the Isolated Elements Effect ............................ 162Expertise Reversal and the Variability Effect ....................................... 163

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Pre-Training and the Expertise Reversal Effect .................................... 164Expertise Reversal for Multimedia and Hypermedia Representations ......................................................... 165

The Expertise Reversal Effect and Aptitude-Treatment Interactions ....... 167Conditions of Applicability of the Expertise Reversal Effect ................... 167Instructional Implications ......................................................................... 168Conclusions ............................................................................................... 169

13 The Guidance Fading Effect .................................................................. 171

Empirical Evidence for the Guidance Fading Effect ................................ 172Effects of Fading Worked-Out Solution Steps ...................................... 173Knowledge-Dependent Dynamic Provision of Guidance ..................... 174The Effect of a Gradual Change in Levels of Support Using Computer-Based Tutors ............................................ 176Applying Rapid Assessment Techniques to the Design of Adaptive Fading Procedures ............................................................. 177

Conditions of Applicability of the Fading Effect ...................................... 181Instructional Implications ......................................................................... 182Conclusions ............................................................................................... 182

14 Facilitating Effective Mental Processes: The Imagination and Self-Explanation Effects .................................................................. 183

The Imagination Effect ............................................................................. 183The Imagination Effect Prior to Cognitive Load Theory Research .......... 185Empirical Evidence for the Imagination Effect Within a Cognitive Load Theory Context ................................................. 186The Self-Explanation Effect ...................................................................... 187Conditions of Applicability....................................................................... 190Instructional Implications ......................................................................... 192Conclusions ............................................................................................... 192

15 The Element Interactivity Effect ........................................................... 193

Empirical Evidence for the Element Interactivity Effect .......................... 194Element Interactivity and the Split-Attention and Redundancy Effects ........................................................................ 194Element Interactivity and Understanding Instructions .......................... 196Element Interactivity and the Modality Effect ...................................... 197Element Interactivity and the Expertise Reversal Effect ...................... 198Element Interactivity and the Imagination Effect ................................. 199

Conditions of Applicability....................................................................... 199Instructional Implications ......................................................................... 200Conclusion ................................................................................................ 201

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16 Altering Element Interactivity and Intrinsic Cognitive load .............. 203

Pre-training ............................................................................................... 204Focusing on Subgoals ............................................................................... 205Presenting Declarative and Procedural Information Separately ............... 206Reducing Intrinsic Load in Worked Examples ......................................... 206Isolated Elements Effect ........................................................................... 2084C/ID Model for Complex Learning ........................................................ 211The Variability Effect ................................................................................ 212Variability and Increased Intrinsic Cognitive Load .................................. 215Conditions of Applicability....................................................................... 216Instructional Implications ......................................................................... 216Conclusions ............................................................................................... 217

17 Emerging Themes in Cognitive Load Theory: The Transient Information and the Collective Working Memory Effects .................. 219

The Transient Information Effect .............................................................. 219The Modality Effect and Transient Information ................................... 220Instructional Animations and Transient Information ............................ 222Animation Versus Static Presentations ................................................. 223Some Conditions Under Which Animations Can Be Effective ............ 224Learning Human Movement or Motor Skills: A Special Case ............. 226The Role of Biologically Primary Knowledge ..................................... 227Conditions of Applicability................................................................... 229Instructional Implications ..................................................................... 229Conclusions ........................................................................................... 229

The Collective Working Memory Effect ................................................... 230Conditions of Applicability................................................................... 232Instructional Implications ..................................................................... 233

Conclusions ............................................................................................... 233

Part V Conclusions

18 Cognitive Load Theory in Perspective .................................................. 237

References ........................................................................................................ 243

Index ................................................................................................................. 263

Cognitive Load TheoryPrefaceAcknowledgementsContents