Theory of Mind and Communication in Autism Francesca Gabrielle Elizabeth Happe, MRC Cognitive Development Unit, and Department of Psychology, University College, London. Thesis submitted for the degree of Ph.D. in Psychology, University of London. October, 1991. 1 Acknowledgements My greatest thanks must go to Uta Frith, who made writing this thesis not only possible but pleasurable. I have benefitted enormously from her unstinting encouragement, her insightful criticisms, and her great kindness. I would also like to thank all my colleagues at the MRC Cognitive Development Unit, particularly Annette Kanniloff-Smith, Alan Leslie and John Morton, for teaching me so much which I hadn't realised I didn't know. Thanks also go to Fran Siddons, James Blair and other friends, who have been invaluable in the discussion of fledgling ideas. I am also extremely grateful to the autistic children and adults who took part in the studies reported here. They, along with their teachers and parents, have taught me a great deal about autism, and shown me how much more there is still to discover. Lastly, my thanks go to my family for their unfailing support and enthusiasm. A.M.D.G. 2 Abstract Recent work investigating the biological and cognitive nature of autism is reviewed. The hypothesis that autistic individuals suffer from a specific impairment in theory of mind, and the relevance of this notion to the diagnosis of Asperger's syndrome, is discussed. Theory of mind explanations of autism must account for the minority of autistic subjects who pass false belief tasks. Two possible accounts are considered; delay versus "hacking". A battery of theory of mind tasks was given to able autistic subjects, and to mentally handicapped and young normal controls. The results suggested the existence of subgroups: while some autistic subjects performed inconsistently (perhaps using task-specific strategies), others performed consistently well at first-order theory of mind tasks, and some passed an array of second-order tasks. Relevance theory suggests that understanding mental states is vital in communication. Communication tasks were therefore given, to explore the theory of mind abilities of the autistic subjects. Relevance theory predicted that subjects unable to attribute mental states would show literal understanding, subjects with first-order theory of mind would comprehend metaphor, but second-order theory of mind would be necessary to understand irony. These predictions were tested and confirmed with autistic subjects and normal children. The theory of mind hypothesis cannot explain the persistent real-life handicaps of autistics who understand mental states, nor account for the nonsocial peculiarities seen in autism. A deficit in central coherence is suggested as the source of these features. Results from a preliminary test of this hypothesis suggested that even autistic subjects who develop theory of mind ability are impaired at extracting context-dependent meaning. The implications of these findings for the diagnosis of Asperger's syndrome, the relations between the social and nonsocial impairments, and suggestions for further research are discussed. 3 Table of Contents Chapter 1 Autism and Theory of Mind 13 Necessary and Sufficient Features 13 Explaining autism: Levels of description 18 Biology and brain 19 Cognitive explanations 22 Theory of mind and the understanding of false belief 24 The metarepresentational deficit theory of autism 29 What exactly do autistic subjects fail to represent? 33 The troublesome talented minority 39 Conclusions 43 Chapter 2 Asperger's Syndrome 44 Asperger and Kanner; differences and similarities 44 Diagnosis 48 Differential diagnosis of Asperger's syndrome 56 Semantic-Pragmatic Disorder 57 Right Hemisphere Learning Disabilities 59 Childhood Schizophrenia and Schizoid Personality Disorder 62 Asperger's syndrome and autism: How different is different enough? 68 Conclusions 76 Chapter 3 The Theory of Mind Battery 78 Introduction 78 Method 81 Subjects 81 Materials 83 Procedure 83 Results 84 Group differences 85 Performance versus justification 86 Deception versus false belief 87 4 Effects of theory of mind level 89 Discussion 91 Group differences: On first-order tasks 91 Group differences: On second-order tasks 91 Performance versus justification 92 Deception versus false belief 93 Theory of Mind Battery Conclusions 94 Chapter 4 The "Strange Stories" Test 96 Introduction 96 Method 97 Subjects 97 Materials 100 Procedure 100 Scoring procedure 102 Covalidation of scoring procedure 103 Results 105 Discussion 117 Chapter 5 Theory of Mind and Relevance Theory 123 Cognitive Economy: The problem of optimal allocation of central processing resources 123 To Communicate is to Claim the Hearer's Attention 124 In autism? 125 Communication versus Language 125 In autism? 126 Two ways to communicate: Coding versus inference 126 in autism? 127 Inferential Communication and the recognition of intent 128 In autism? 128 Recognising intentions allows the same sentence to convey different meanings 130 In autism? 131 Interpretive and Descriptive Representations 133 5 The possible points of breakdown in autistic relevance 135 Predictions from Relevance Theory: Simile, Metaphor and Irony 137 Conclusions 138 Chapter 6 Relevance and Communication Tasks 140 Introduction 140 Relevance Battery 144 Subjects 144 Experiment 1: The Idioms Task 147 Method 147 Results 148 Discussion 150 Experiment 2: Simile versus Metaphor 152 Method 153 Results 154 Discussion 157 Experiment 3: Metaphor versus Irony 157 a) Understanding of metaphor versus irony in autistic subjects grouped by theory of mind performance 158 Method 158 Results 159 Discussion 162 b) Understanding of metaphor versus irony in young normal subjects with and without second-order theory of mind 162 Subjects 162 Method 163 Results 163 Discussion 164 Relevance Battery Summary and Conclusions 165 Chapter 7 Relevance and Central Coherence 168 Background to Frith's notion of Central Coherence 168 Frith's notion of Central Coherence 173 Extending the Central Coherence hypothesis: Coherence and Relevance 174 6 Testing the Central Coherence hypothesis 177 Chapter 8 The Homograph Task 178 Introduction 178 Method 180 Design 180 Subjects 180 Materials 181 Procedure 182 Results 183 Discussion 186 Chapter 9 Future Directions 189 Introduction 189 Understanding the handicap in Asperger's syndrome 190 Possible relations between central coherence and theory of mind 193 Continuous and discrete impairments 197 Central Coherence: Predictions, existing findings and suggested studies 199 Prediction . 1 201 Prediction 2 201 Prediction 3 203 Prediction 4 206 Prediction 5 208 Existing findings outside autism research 212 Central Coherence in right hemisphere disorders 212 Central Coherence in normal subjects - a cognitive style? 216 Concluding comment 220 Bibliography 222 Appendix I 254 Theory of Mind Task Protocols 254 First-order False Belief Tasks 254 7 First-order Deception Tasks 256 Second-order False Belief Tasks 257 Second-order Deception Tasks 259 Individual Subject Characteristics and Theory of Mind Battery Results 262 Appendix II 265 "Strange Stories" Battery Materials 265 Instructions to young normal subjects 265 The "Strange Stories" 266 Physical stories 278 Examples of subjects' answers to the "Why?" question 280 Covalidation of story ratings 281 Individual Subjects' Results from "Strange Stories" 282 Appendix III 284 Materials from Relevance Battery 284 Experiment 1: Idioms task materials 284 Experiment 2: Simile versus Metaphor task materials 285 Experiment 3: Metaphor versus Irony task materials 289 Individual Data from Relevance Battery 291 Appendix IV 292 Homograph Task Materials 292 Pretest 292 Test 292 Individual Data from Homograph Task 294 8 List of Tables Table 1.1 Summary of Biological factors in autism 20 Table 1.2 Studies relevant to theory of mind in autism 27 Table 2.1 Szatmari et al's (1989) criteria for Asperger's syndrome 52 Table 2.2 Criteria for Asperger's syndrome in the draft of ICD-10 55 Table 2.3 Van ICrevelen's distinguishing features of Asperger's syndrome 69 Table 3.1 Subject characteristics for theory of mind battery 82 Table 3.2 Results from theory of mind battery 84 Table 3.3 Percentage of subjects passing all false belief/deception tasks 87 Table 3.4 Percentage of subjects who pass false belief but not deception 88 Table 3.5 Percentage of subjects passing all 1st- or 2nd-order tasks 89 Table 3.6 Percentage of subjects passing 1st- but not 2nd-order tasks 90 Table 4.1 Subject characteristics for "Strange Stories" battery 99 Table 4.2 Percentage (and number) of concordant ratings of justifications 104 Table 4.3 Results for "Strange Stories"; number of justifications 106 Table 4.4 Results for "Strange Stories"; for autistics grouped by theory of mind performance 110 Table 4.5 Numbers of subjects giving at least one incorrect mental state justification; by subject group and story type 114 Table 4.6 Numbers of subjects giving at least one incorrect mental state justification; autistics grouped by theory of mind 116 Table 6.1 Subject characteristics for the Relevance Battery 145 Table 6.2 Idioms task results: percentage of subjects preferring literal versus idiomatic interpretations 148 Table 6.3 Idioms task results: number of idiomatic choices made 150 Table 6.4 Sentence completion task: results from autistic subjects grouped by theory of mind performance 154 9 Table 6.5 Sentence completion task: results from "no theory of mind" autistics and MU) controls 155 Table 6.6 Metaphor