Autism: A New Introduction to Psychological Theory and Current Debate - Tiffany Watt Smith 2019


ORIGINALLY PUBLISHED IN 1994, this book has now been rewritten and updated dramatically to reflect the significant strides that have been made, not just in psychological research and theory but in socio-political theorising about autism, and in public awareness and acceptance. Nevertheless, the aim of this book remains the same — to acquaint you with current research and thinking about autism in a concise yet comprehensive way. We focus particularly on the cognitive level of explanation, which is the purview of psychological research. At the end of each chapter, recognising the fast pace of thinking about autism, we highlight current “big questions” for the field. In each chapter, we have also invited autistic people to provide their personal perspectives. These sections will, we hope, contextualise the content by providing relevant insights into the lived experience of autism. Our goal is to ensure that this academic text is firmly embedded in real-world, community priorities.

Further reading is suggested in two ways — references in the text will allow you to find out more about specific issues raised, while suggested reading (usually in the form of books or review articles) appears at the end of each chapter, allowing you to deepen your knowledge of those aspects of autism that particularly interest you. Throughout the book, discussion has been kept as brief as possible in the hope that the book will provide a manageable overview of autism, tying together a number of quite different areas. It should whet your appetite for the more detailed consideration of specific aspects of autism provided by the suggested readings.

1. Levels of explanation

If a Martian asked you what an apple is, you might reply that it is a fruit or that it is something you eat, you might describe it as roundish and red, or you might try to give its composition in terms of vitamins, water, sugars and so on. The way you answer the question will probably depend on why you think the Martian wants to know — are they hungry, do they want to be able to recognise an apple or are they simply curious? None of these answers is the answer, since each answer is appropriate for a different sense of the question. Similarly, different types of answer can be given to the question, “What is autism?” In order to find the right answer for the question in any one context, we need to think about our reasons for asking. One can think about this distinction between the different senses of a question in terms of different levels of explanation.

In the academic study of autism, three levels in particular are useful; the biological, the cognitive and the behavioural. It is important to keep these levels distinct, because each of the three levels does a different job in our understanding of autism. So, for example, to inform the search for possible causes of autism, it may be appropriate to look at biological features, while to address family priorities, it may be more important to consider the behavioural description.

Morton and Frith (1995) introduced a specific diagrammatic tool for thinking about levels of explanation in developmental conditions such as autism. Figure 1.1, taken from Morton and Frith (1995), shows their causal models of the three levels and the possible relations between these levels in different diagnostic categories. Pattern (a) is the case of a condition defined by its unitary biological origin, which may have diverse effects at the cognitive and behavioural levels. An example of this type of condition might be Fragile X syndrome, as currently conceptualised; Fragile X syndrome is diagnosed in the presence of a specific gene mutation on the X chromosome. However, not all individuals so defined have the same cognitive or behavioural features; while many will have severe learning difficulties and social anxiety, others may have an IQ score in the average range and appear socially confident.

Pattern (b) shows a condition with multiple biological causes, and several different behavioural manifestations, but a single defining cognitive feature. Dyslexia, according to some cognitive theories (e.g. Hulme & Snowling, 2016), may be an example of such a condition. A number of biological causes may converge in causing a cognitive difference in the phonological system, leading in turn to multiple behavioural difficulties (e.g. with reading, spelling, auditory memory, rhyme and sound segmentation). Many attempts have been made to characterise autism in this way (see Chapter 6).

Pattern (c) is the case of a condition defined by its behavioural features alone, with multiple biological causes and cognitive natures. Conduct disorder, as currently diagnosed, may be such a condition; children who show antisocial behaviours, for whatever reason, may be grouped together under this label for the purposes of understanding and support.

Figure 1.1 Causal models of three types of disorder

Reproduced from Morton & Frith (1995) by kind permission of the author.

Throughout this book, we will be using the notion of levels of explanation, to keep separate different issues and questions. In Chapter 3, the diagnosis of autism is discussed, and the focus is on the behavioural level — since autism is currently recognised on the basis of behavioural features rather than, for example, biological etiology. In Chapter 4, the biological level is addressed, since research suggests that ultimately autism is rooted in genetic factors. In subsequent chapters the remaining of the three levels is discussed — the cognitive level.

Cognitive theories aim to span the gulf between biology and behaviour — between the brain and action — through hypotheses about the mind. This level, the level of cognition, is the primary focus for this book. The term cognitive is used here not in contrast to affective; we do not promote a dichotomy of ’rational’ versus ’emotional’ states. Rather, it is intended to cover all aspects of the working of the mind, including thoughts and feelings. This level of analysis might also be called the “psychological” level, except that psychology also includes the study of behaviour.

Keeping the three levels of explanation (biology, cognition, behaviour) distinct, helps in thinking about a number of issues to do with autism. So, for example, people often ask whether autism is part of the ordinary continuum of social behaviour — are we all “a little bit autistic”? The answer to this question is likely to be different at the different levels of explanation. At the behavioural level the answer may appear to be “yes”, at least in some respects. For example, an autistic person may behave much like a very shy, but non-autistic, person in some situations. Nearly everyone — autistic or not — has some motor stereotypies (e.g. finger tapping). Here, the uniquely autistic experience may be to do with quality and how such behaviours co-occur. For example, the difference between one person’s sensory sensitivity to artificial lighting and another person’s autism is not simply a matter of intensity of reaction, but of patterning and complexity.

At the biological level, the answer is also complicated. In some cases, autism is linked to rare genetic mutations, not present in neurotypical individuals. However, in most cases, the genetics of autism is more like the genetics of height; lots of common genetic variants contribute to the outcome for an individual. It appears that these common variants, each of tiny effect, contribute both to diagnosed autism and to subclinical traits. At the cognitive level, too (depending on the theory you endorse), autistic people may be quite distinct from the neurotypical range. So, for example, very different cognitive reasons may underlie apparently similar behaviour by individuals with and without autism — think of an autistic person and a “normal” rebellious teenager, both of whom may dress unconventionally for a job interview. Likewise, an autistic child’s social difficulties might have a quite different cause (at the cognitive level) from a non-autistic shy person’s — although the behaviours produced (avoiding large groups, social anxiety, limited eye contact) may be very similar. We’ll return to this interesting question in Chapters 8 and 9.

At the cognitive level of explanation, in Chapter 5, we will first provide an overview of how the cognitive level may be used to link behavioural and biological features. We will review criteria for a good psychological theory, considering quality and quantity of evidence and practical impact. Subsequently, Chapters 68 will describe and evaluate the available cognitive models of autism in three distinct groups. Primary deficit models attempt to identify a single difference (nearly always characterised as a deficit), which has a root, causal role in determining autism. Developmental progress models tend to frame autism as the result of multiple interacting processes across early development. Cognitive difference models are concerned with the complex ways in which people with autism relate to their environments and attempt to characterise autism on that basis.

In the final two chapters of the book, we will review the contribution that psychological theory has made to our understanding of autism and to practice in schools, clinics and beyond. This will include a discussion of alternative approaches to understanding autism — e.g. sociological models — and the possibility that our biological-cognitive-behavioural framework would benefit from the addition of a fourth level of explanation. In Chapter 10, we wrap up with a discussion of the key issues for the future of autism research.

2. Timescales of explanation

As well as trying to answer the question, “What is autism?”, this book explores why or how autism occurs. In other words, this book is concerned with causal theories of autism. In thinking about causal explanations, it is useful to keep distinct not only three levels of description but also three timescales. Causes can be examined in terms of evolutionary time, taking as the unit for discussion the gene and considering pressures acting in the process of natural selection. A second timescale of cause is development, where the individual (or the biological, behavioural or cognitive mechanism within the individual) is considered. Developmental time includes key features like the existence of sensitive periods in some systems, where a specific window of time may exist for specific causes to have specific effects (e.g. imprinting in the chick) — the same causal agent acting on the organism after this time will not have the same consequences. Lastly, there is the time span of “online” mechanisms — that is moment-to-moment or processing time.

In considering autism, the latter two timescales are particularly important (see, for example, Chapters 6 and 7). An example may help to clarify the distinction and to illustrate that the same influence may have rather different effects in terms of disruptions to development and disruptions to processing.

Think of the effects of large quantities of alcohol acting as a cause on the three timescales. In evolutionary time, imagine that the existence of alcohol in foodstuffs leads to the selection of individuals with the ability to taste this substance and avoid consuming large quantities of foods containing alcohol — since being drunk does not increase reproductive success! In developmental time, alcohol has different effects — in large quantities, it may hamper the physical and mental development of the foetus. Later in the life course, but still in developmental terms, intake of large quantities of alcohol may have long-term effects on adults, for example, cirrhosis of the liver. In terms of processing time, however, the effects of alcohol are usually pleasant — that’s why we drink it! In large amounts, though, it has effects on our behaviour, for example, causing slurring of speech and loss of balance. These are “online” effects in the sense that they persist only for so long as the maintaining cause is there — the high blood alcohol level. The developmental effects, however, will persist, even after the individual has sobered up. This example may seem a long way from autism but, as will emerge in Chapters 7 and 8, psychological theories of autism can be very different depending on whether they focus on developmental or processing causes.

In the context of autism research, we might also ’zoom in’ on the developmental timescale a little more closely. Autism is characterised as a ’neurodevelopmental’ condition, meaning that it emerges from differences in brain development. Two key lessons emerge from this characterisation of autism. One is that any research needs to take into account the chronological age of the participants and, if different, their developmental level too. Without this context, it is impossible to determine whether a behaviour is typical or atypical, delayed or divergent, concerning or not. Take as an example the typical child’s learning of irregular past tenses, which follows a u-shaped curve. In early development, children learn and imitate the correct irregular forms of verbs and plurals (e.g. “we went to the park”; “I saw two sheep”). Later, as children, from about 2 years, start to recognise and apply grammatical rules, they tend to overgeneralise these, making charming over-regularisation errors (“we goed to the park”; “I seed two sheeps”). And later still, children competently apply grammatical rules and have learnt the cases where an irregular form is correct.

We can see from this example how important it is to understand the developmental stage reached by an individual before passing judgement on their competence. Developmental processes do not necessarily follow simple upward trajectories from less to more skilled. Moreover, the same pattern of behaviour (in this case, correct use of irregular word forms) may be apparent at different stages for different reasons (in this case, mimicry versus mastery). One relevant example more specific to autism relates to the prevalence of restricted and repetitive behaviours in children: a large survey of typically developing toddlers showed that behaviours like lining up toys, hand- flapping and specific narrow interests are very common in 2-year-olds (Leekam et al., 2007). This kind of information is essential when, among other things, attempting to identify markers of autism in early development. Understanding how and why children engage in such patterns of behaviour can also play a role in understanding the possible function of these repetitive movements and activities in the life of someone with autism.

Developmentally sensitive research is vital for at least three reasons. First, longitudinal studies help untangle cause and effect, and move us beyond inspecting correlation to inferring causation. We’ll see this in Chapter 7, where we look at studies of infants genetically predisposed to autism. Second, developmental trajectories can uncover importantly different sub-groups and help distinguish ’phenocopies’. For example, although many of the young children adopted from terrible deprivation in Romanian orphanages showed autistic- like behaviours, most grew out of these in a way not typical of autism. Third, cross-sectional research that takes a ’snapshot’ at one age is subject to confounds, including cohort effects. This is very relevant to the study of ageing in autism, discussed in Chapters 3 and 10, because diagnostic criteria were much narrower in the 1960s and ’70s than today, the picture we see in autistic 60-year-olds diagnosed in childhood is likely to be quite different from that for a newly diagnosed 60-year-old, or for today’s autistic children when they reach 60.

3. Some facts and fiction

At this point in the original version of this book, published in 1994, an attempt was made to clear up a series of myths and misunderstandings about autism. Rather than replace these with a new list, we replicate the original here and provide some commentary on each item. It is fascinating and instructive to consider how much the field has moved on, but also how some of these myths have stuck around for so long.

1  Autism is not caused by “refrigerator parenting”.

The ’refrigerator mother’ is a mythical creature — described in more detail in Chapter 2 — whose cold parenting was supposed to cause autism. Thankfully, the belief that parenting styles cause autism is largely dispelled, and we might not need to flag this nowadays. However, a high-pressure focus on the parent remains. The current practical guidance on autism is often focused on ’early intervention’ as a way to prevent what are seen as negative outcomes for autistic children. Following diagnosis, parents are often under pressure to find ’solutions’ and to do so quickly — there is a sense of time running out. Instead, parents of newly diagnosed children would benefit from more encouragement to find things their child loves and do them often; advice on creating a safe, predictable environment in the home; and support for their whole family’s adjustment and well-being. So, although this myth is now less influential, there remains a wider problem in supporting parents raising children with autism. Autistic parents are more likely to have autistic children (since autism is highly heritable) but recognition of this group’s existence, let alone support for their particular needs, remains very poor.

2  Autism is a biologically based disorder.

This one is also certainly true, but it is striking that little progress has been made in determining precisely what this biological basis is. As we will see in Chapter 4, genetic, neurological and any other biological markers of autism remain elusive.

3  Autism is not confined to childhood.

4  Autism is a developmental disorder which lasts throughout life.

These two are also still accurate, though now we would use ’difference’, ’condition’ or perhaps ’neurotype’ rather than disorder. It remains a consistent criticism of research that lifespan issues are rarely taken into account and a disproportionate amount of research focuses on children. This is partly due to challenges recruiting autistic adults (see Chapter 3) and the scientific priority given to understanding causal factors and mechanisms, which often means studying childhood.

5  Autism is not always characterised by special, or “savant”, skills.

6  Autism is found at all IQ levels, but is commonly accompanied by general learning difficulties.

7  Autism is not just a “shell” within which a “normal” child is waiting to get out.

These characterisations of autism are not inaccurate but the details and language have shifted, as have the issues one might choose to flag up today. In particular, estimated rates of learning disability in the autistic population vary widely, but are often around 50% — a much lower proportion than was thought in 1994 (Elsabbagh et al., 2012). Savant skills have been reported in a third of adults with autism (Howlin et al., 2009), and more generally, an uneven profile across standard ability tests is very common. While many autistic people might perform poorly in specific domains of standardised testing, in tests of visuo-spatial reasoning or pattern recognition, their strengths may come to the fore (Courchesne et al., 2015). It is true that autism is not covering up a “normal” child, and the neurodiversity movement that has developed since the original edition of this book celebrates that difference, rather than seeing autism as a failure to match the ’typical’.

It is also important to note that while autism is lifelong, it is not a life sentence — autistic people (both with and without a learning disability) have, and do, and can, achieve great and beautiful things. An autistic person’s personal satisfaction with their life depends not so much on their being autistic, as on the capacity and willingness of those around them to understand, accept and support them. Throughout this book, we hope to employ psychological theory and evidence to promote such understanding, recognising differences, without labelling autistic people as deficient or inferior.

8  Autism is a severe disorder of communication, socialisation and imagination.

The more researchers have learnt about autism, the harder it gets to sum up the condition in a single sentence — and that’s just drawing on research evidence, let alone the multiplicity of lived experiences. We can say categorically how autism is diagnosed, but that’s not the same as what it is. In each of these listed domains, evidence for differences is mixed. That isn’t to say that differences don’t exist — they do, and sometimes they are disadvantageous — but the precise nature of the difference is hard to pin down.

What about severity? As you will see in Chapter 3, we believe that attempting to use ’severity’ estimates to describe autism is futile. When invoking a concept of severity, what we are usually trying to capture is the level of support an individual requires — in which case reporting the support need itself is both more accurate and more helpful. While this book characterises autism in terms of difference rather than deficit, there is no doubt that some of the experiences that typically accompany autism — poor sleep, restricted diet, epilepsy, language delay, learning disability and poor mental health, not to mention encountering prejudice, bullying and discrimination — can be severely upsetting and disabling.

What new facts might we add to counter more recent myths? An obvious one would be ’vaccines do not cause autism’. This scare is entirely traceable to flawed and sometimes actively fraudulent science. There is now a vast and conclusive body of evidence disproving the link between vaccines and autism. We might also emphasise that ’not all autistic people are male’, given that research has often overlooked or even systematically excluded women, girls and non-binary people from autism studies.

4. Current debates


This book will be structured around two descriptive frameworks. First, we will consider autism at different levels of explanation: biological, cognitive and behavioural. In our pursuit of accurate models of the causes and nature of autism, we will also consider different timescales of influence: evolutionary, developmental and online. Since autism is now characterised as a developmental condition — with a manifestation that changes in important ways across different life stages — the developmental timescale will be particularly important in considering psychological models. We have seen how radically the understanding of autism has changed since the last version of this book was published. In this new text, we attempt to address the ever-changing understanding of autism by highlighting topical issues and big questions for the future at the end of every chapter.

Big questions

One question we grappled with while writing this book is, what right do we have as neurotypical researchers, without lived experience of autism, to write an authoritative text on autism? We couldn’t possibly write a book about the experience of autism, of course — but we are psychologists, and so we can try to write about psychological theories of autism. We hope it is legitimate for us to have a platform to present and discuss those theories, but we are very aware that there are many other ways to view autism. These include other disciplinary perspectives, but also — very importantly — autistic voices and experiences. We wanted to give space in our book for stakeholders to comment and reflect, providing a contrasting, critical perspective or enriching our academic content with personal experiences.

This leads to another big question — how to incorporate autistic voices without tokenism? In the context of this book, we have invited people to contribute by identifying a core theme within each chapter and asking an interested person to comment on that theme. Our goal is to include autistic contributors whose personal experience actively resonates with the topic of each chapter.

A final point to raise is that these written accounts from autistic people are not accessible to the very large proportion of the autistic community who aren’t able to read or write with confidence — young children and people with learning disabilities or limited language. In an attempt to represent these people, some of our contributors are autistic parents of autistic children, or autistic professionals who have day-to-day contact with autistic people who are less able to speak for themselves. Others had a profile in childhood which might then have been designated ’severe autism’, but have acquired a lot of communication skills since that time.


In reading this broad chapter, I think an important thing to remember is that scientific theories of autism focus on differences between people with and without autism, or differences associated with certain autistic traits in the population. They do not describe autistic people themselves, nor their lived experience. It is easy to read about autism and picture an ’autistic person’ (usually a child or someone we know), whose personality and experience of the world are almost built around the differences or autistic traits described. Scientific theories focus on differences because these can help us understand what the condition of autism is. However, people are more than just bundles of measurable traits, and each autistic person is first and foremost a human, with a lived experience that is often closer to what we would think of when we imagine any human life. For instance, I have quite typical long-term goals, ambitions and challenges for someone of my age and in my career. However, as a result of autism-related sound sensitivity, I also experience a lot of stress from excessive noise in my household and neighbourhood. This has affected my mental health and my ability to study and has made it difficult to find a suitable place to move out. However, rather than having defined my life, this feature of autism has made it more difficult for me to focus on my otherwise ’normal’ goals.

More generally, each autistic person has his or her own personality, priorities and preferences, goals and struggles. I have met quite a few people with autism, all with very different personalities to me. Some I liked and others I very much disliked! Perhaps surprisingly, I consider most of my ’neurotypical’ friends more similar to me than any autistic person I’ve met so far. Similarly, while some autistic people embrace an autistic identity, others do not consider it a central part of their life or personality. By adulthood, many autistic people will also have one or more comorbid conditions, and these might feature more prominently in their everyday life than features of autism. Crucially, each individual with autism has their own unique strengths, difficulties and needs, and these should be the central concern for anyone who wants to work with autistic people. Understanding autism can make it easier to help autistic people, but I would urge the reader not to think of autism as a personality, or a different ’type’ of person. Instead, think of it as a set of changes to an otherwise very human life. These changes can be extreme or not so extreme, positive or negative, and can make for a meaningful but often tumultuous experience.

Recommended reading

Karmiloff-Smith, A. (1998). Development itself is the key to understanding developmental disorders. Trends in Cognitive Sciences, 2(10), 389—398.

Kenny, L., Hattersley, C., Molins, B., Buckley, C., Povey, C., & Pellicano, E. (2016). Which terms should be used to describe autism? Perspectives from the UK autism community. Autism, 20(4), 442—462.

Milton, D. E. (2014). Autistic expertise: A critical reflection on the production of knowledge in autism studies. Autism, 18(7), 794—802.