- If it turns out that some other deficit underlies the theory of mind deficits in autism, then Tomasello would have to revise his hypothesis to admit at least one other cognitive adaptation in humans.
- As Clark notes, many autistics are able to function quite well in non-social tasks. In fact, at the top end of the autism spectrum, individuals with Asperger Syndrome show the marked social deficits that characterize autism spectrum disorders, but are able to learn and reason in a way that is uniquely human, including developing language at a normal rate. There are people with Asperger Syndrome in physics departments and writing brilliant music, things that no nonhuman animals can do. If Tomasello is going to explain uniquely human cognitive abilities by reference to theory of mind and the cultural learning that it allows, then Asperger Syndrome and other high-functioning autistic individuals represent a wrench in his argument.
Most of the work on the relationship between theory of mind and autism has been conducted by Simon Baron-Cohen and his colleagues. Baron-Cohen (B-C) has theorized that there are two general cognitive styles: empathizing and systemizing. Empathizing, according to B-C, consists of a "drive to identify emotions and thoughts in others and to respond to these appropriately" (p. 302). Systemizing, on the other hand, involves "drive to analyze and build systems, with the aim of understanding and predicting non-agentive events" (p. 302)1. He believes that there are three general types of individuals: those who have strong empathizing skills and relatively weak systemizing skills; those who have strong systemizing skills and weak empathizing skills; and those who have balanced empathizing and systemizing skills. On average, males tend to be strong systemizers, while women tend to be strong empathizers. B-C has used this classification system to explain all sorts of behavioral differences between males and females, including differences in mathematical ability. While his theory that males and females exhibit differences in these abilities, on average, is highly controversial and, to say the least, not widely accepted among cognitive psychologists (see, e.g., this paper for a short critique of his empirical evidence), B-C has extended it to explain many of the symptoms of autism spectrum disorders. He believes that individuals with autism are extreme systemizers, and thus calls his theory the Extreme Mail Brain theory of autism2.
B-C has conducted what I consider to be thoroughly uninteresting experiments to test his systemizing-empathizing view of autism, using mostly Asperger patients. Here's an example experiment3: Asperger patients and non-autistic individuals, who have been matched for IQ (in other words, there's no IQ difference between the two groups) are given a systemizing and an empathizing task. The systemizing task involves making predictions in a simple folk mechanics task, while the empathizing task involves recognizing social faux pas in a set of social stories.
Pause here for a moment here, and look briefly at the diagnostic criteria for autism and Asperger specifically. You'll notice that one of the diagnostic criteria for Asperger (A. 3) is almost identical to B-C's definition of empathizing! Furthermore, one of the most common symptoms of both Asperger Syndrome and autism in general is an inability to perceive social nuances. I'll give you a real life examples. Asperger patients tend to have little knowledge of what is and is not appropriate in a given social context, and thus are unable to recognize faux pas. A doctor I know who works with Asperger patients once met with one for the first time, and in the course of their conversation, the patient used the word "fuck" constantly. He didn't know this doctor from Adam, and any non-autistic person would have avoided cussing in that context, but the Asperger patient used it over and over and over again. Another consequence of failing to pick up social nuances is an almost complete inability to recognize lies and figurative speech, and thus take everything literally. Here's another real life example. Another doctor I know was meeting an Asperger patient for the first time. The patient had just come from the funeral of a male cousin. When he told the doctor this, the doctor said, "Oh, I'm sorry, were you close to him?" The patient replied, "About 5 feet."
In short, B-C's empathizing is exactly what we already knew individuals who fall within the autism spectrum don't do very well! So imagine the surprise B-C and his colleagues must have felt when they learned that Asperger patients performed worse on the faux pas task than non-autistic individuals! I don't think I need to point out to you that if they hadn't performed worse, THEY WOULDN'T BE AUTISTIC! That's not a prediction, it's a truism. It might be somewhat surprising that they found that on a folk mechanics tasks, in which the participants had to had to predict the movement of objects in diagrams, the Asperger patients performed better on average than the non-autistic females (there was no difference between the Asperger patients and non-autistic males). From this, B-C concludes that Asperger patients do, in fact, have extremely male brains (though it would appear that at the top end of the spectrum, Asperger patients just have normal male brains).
OK, now that I've gotten my utter dismay at that totally inane experiment out of my system, I can move on to B-C's more interesting work. This work is on the actual relationship between theory of mind and autism. He and his colleagues have conducted more than 30 experiments, most of which used some version of the false belief task, on children with autism, and in almost every case, autistic children show developmental delays in theory of mind. Of course, there are problems with the use of false belief tasks in testing theory of mind abilities. He and his colleagues have also conducted neuroimaging research, focusing on the amygdala. The amygdala is thought to be important for social reasoning, particularly in the recognition of thought, intention, and emotion in the faces of other individuals. In one experiment, individuals with Asperger syndrome and normal individuals (matched for IQ, again) looked at photos of people's eyes (which also show the eyebrows, and parts of the nose and forehead), and attempted to guess what the people were thinking. Non-autistic individuals perform quite well on this task, while Asperger patients perform very poorly. While the participants were performing the task, their brains were scanned using an fMRI machine. Consistent with the theory of mind theory of autism, non-autistic participants displayed increased activation in the amygdala, while Asperger participants displayed no increased activation, when performing the task4. If you want to look at the figure above (from the Baron-Cohen et al. paper, see footnote 4), the sides are reversed (the right side of the figure is the left side of the brain), the yellow indicates that the area was only active in the non-autistic participants, the red indicates that the area was only active in the Asperger participants, and the blue indicates that the area was active in both. The left amygdala is that little yellow area of activation that is in the middle (from top to bottom) and slightly to the right (meaning it's on the left side of the brain) in the image labeled -7.
In addition to the amygdala theory of autism and theory of mind, others have argued, speculatively, that a type of neuron that may be found in the human left prefrontal cortex (they're found in the analogous region in monkeys, but there's no direct evidence, as of yet, that they exist in humans) called mirror neurons may be involved in autism as well. In monkeys, mirror neurons facilitate imitation. In humans, left frontal cortex lesions are associated with deficits in the ability to imitate the actions of others. Autism patients also tend to show lower levels of activity in the left medial frontal cortex than non-autistic individuals (e.g., in the Baron-Cohen et al study I just described) in response to theory of mind tasks. Some have speculated, then, that autistic individuals may not have a fully functioning mirror neuron system5. If there is a mirror neuron system in the human left medial frontal cortex analogous to the one in monkeys, then it is likely that this system is associated with theory of mind, and lower levels of activation in this area in autistic individuals indicates that, mirror neuron system or no, an area of their the brains associated with imitation is not as active as it is in non-autistic individuals.
There are some problems with the theory of mind theory of autism. For one, some autistic patients do perform well on theory of mind tasks, and by adolescence, most are able to perform the most common theory of mind task, the false belief test. In addition, it doesn't seem to explain the range of symptoms in the autism spectrum. Asperger patients clearly have serious theory of mind deficits, but show few of the other cognitive or linguistic deficits that characterize more extreme forms of autism. If theory of mind deficits are the primary symptom of autism, how can this be? It certainly doesn't explain B-C's (shitty) data suggesting that autism patients are extreme systemisers. At most, the theory of mind theory just describes the systemizing-empathizing symptoms (remember, people can be balanced -- being good at one doesn't preclude being good at the other). Furthermore, neither the theory of mind theory or B-C's systemizing-empathizing distinction speaks to another aspect of autism. On some types of tasks, even highly autistic individuals tend to perform better than non-autistic individuals (I'll describe some of those tasks in a moment).
The holes in the theory of mind theory of autism have led some to look for alternative theories. The most prominent alternative theory today is the weak central coherence theory, first espoused by Uta Frith6. Frith uses "central coherence" to refer to the tendency of non-autistic individuals to process information globally, e.g., at the level of the scene as opposed to the level of individual objects in the scene. It is this tendency that is responsible, among other things, for the schematic memory effects that have been demonstrated by cognitive psychologists over the last 40 years, and of which I am so fond (as you may know, if you've been reading this blog). In schematic memory effect, people tend to remember the "gist" of a story or scene quite well, but forget many of the specific details. This is because while they encode the details, they don't spend much time processing them, instead focusing their resources on the overall context. Autistics, Frith argues, do the opposite: they focus on the details, to the exclusion of the overall context. Whereas non-autistic individuals process information globally, autistics process it locally.
What's most interesting about this theory is that it makes some very interesting predictions. For instance, it predicts that in certain tasks in which the global focus of non-autistics produces errors or poorer memory, autistics will outperform them. These predictions have been confirmed in several different types of tasks. For example, in one experiment7, Francesca HappéÃ© had autistics look at illusion-inducing visual stimuli, such as the Titchner Circles:
These circles produce a classic perceptual illusion. Non-autistic individuals tend to say that the middle circle in the group on the right is larger than the middle circle in the group on the left, despite the fact that they are the same size.HappépÃ© argues that this is because autistics, because they process each of the circles at the local level, are immune to the illusion-inducing effects of the overal context (the surrounding circles). Elsewhere, she has detailed several other cases in which autistics display similar "local perception biases," including a reduced susceptibility to the McGurk effect, in autistics8.
Autistics also perform better on a different sort of task that requires segmenting parts of a scene instead of analyzing the scene as a whole, or Gestalt. This task, called the Embedded Figures Task, involves finding a shape, or several shapes, that is embedded within a complex scene. Non-autistics tend to be pretty slow at this. Autistics, it turns out, are able to find the shapes faster than non-autistics9. This is consistent with the weak central coherence theory: autistics are able to find the shapes faster because they are processing local features, and are not distracted by the overall Gestalt. Further supporting this view, using the Embedded Figures Task and fMRI, Ring et al.10 found that non-autistic participants showed greater activation than autistic participants in brain areas associated with working memory in the right dorsolateral prefrontal cortex, while autistic participants showed greater activation than non-autistic controls in ventro occipitotemporal regions (the cuneus, infrior occipital gyrus, and middle occipital gyrus), which are parts of the visual system. They interpreted these results as indicating that the control participants were utilizing working memory to analyze the scene as a whole, while autistic participants were using the visual system for "object feature analysis."
In addition to areas in which autistics' performance is superior to that of non-autistics, the areas in which autistics perform as well as non-autistics support a weak central coherence theory as well. For example, while autistics are worse than non-autistics at recalling information that requires global processing (e.g., temporal sequences and the source of a memory), they are just as good at memory tasks that are not always subject to schema effects, such as recognition memory11.
But the most powerful test of a theory of autism is to use it to explain the deficits that appear in autism. This is what the theory of mind theory of autism was designed to do, and the weak central coherence theory will have to do it as well if it is going to be a viable alternative. I'll give one such explanation of a deficit here, and then describe how it might be related to some of the other deficits. A couple years ago, Blake et al.12 conducted an interesting experiment in which they presented autistic children and non-autistic controls with two types of motion. One type involved small lines moving together to form a group. The other involved point-light animation of human movement (see the figures on this webpage to get an idea of what point-light animation is). Autistics and controls performed equally well on the line movement task, but autistics were much worse at recognizing biological motion in the point-light animation task. Blake et al. interpreted this finding as support for the theory of mind theory, arguing that deficits in theory of mind make it more difficult to interpret biological motion.
But there's another possible interpretation. In the same year, Bertone et al.13 published a study in which they presented autistic and control participants with tasks involving two different kinds of motion, and asked them to indicate the direction of motion. The two types of motion in this study were first and second-order motion. Previous neuroscientific research has shown that first-order motion (in this study, motion defined by changing the luminance across the screen), which doesn't involve the integration of multiple sources of information, is processed early in the visual system in the primary visual cortex, while second-order motion (in this case, motion defined by changing texture across the screen) is processed further along in the visual system, because it requires integrating multiple sources of visual information. Bertone et al. predicted that, consistent with the weak central coherence theory, autistics would peform well on first-order motion tasks that do not involve integration, but poorly on second-order visual tasks that do, and thus demand a more global processing approach. And that's what they found. Biological motion tasks like those used in the Blake et al. study are second-order tasks, in that the viewer has to integrate the information (often conflicting, directionally, at the local level) in order to perceive and identify biological motion. It could be, then, as Bertone et al. argue, that difficulties in processing complex, integrated visual information underlie theory of mind deficits in autism, rather than the other way around. Much of what makes up theory of mind in humans involves integrating multiple sources of sensory information at a higher level (e.g., faciaexpressionsns, bodily movements, and auditory cues including verbal and nonverbal expressions). If the primary deficit in autism is one of integrating information at a global level, it stands to reason that theory of mind would suffer (perceiving biological motion certainly would).
Baron-Cohen and some others feel that the weak central coherence theory is actually a compliment to the theory of mind theory. They don't think it can stand on its own. It doesn't, for instance, explain B-C's systemizing v. empathizing data. Then again, neither does the theory of mind theory, but B-C's never let that deter him. But for all intents and purposes, the jury is still out. As of yet, there's no direct data that can directly explain the relationship between global processing difficulties and theory of mind deficits in autism. They may be causally related, they may share a common cause, or they may be completely unrelated. Neither theory can as of yet explain all there is to explain about the cognitive deficits in autism, so it's unlikely that either will end up standing alone. We'll have to wait and see.
1 Lawson, J., Baron-Cohen, S., & Wheelwright, S. (2004). Empathising ansystemizingng in adults with and without Asperger Syndrome. Journal of Autism and Developmental Disorders, 34(3), 301-310.
2 Baron-Cohen, S. (1999). The extreme male-brain theory of autism. In H. Tager-Flusberg (Ed.), Neurodevelopmental Disorders. MIT Press.
3 Lawson, Baron-Cohen, & Wheelwright (2004).
4Baron-Cohen, S., Ring, H.A., Bullmore, E.T., Wheelwright, S., Ashwina, C., & Williams, S.C.R. (2000). The amygdala theory of autism. Neuroscience and Biobehavioral Reviews, 24, 355Ã–364. The brain scans are from Figure 2, p. 361.
5 Williams, J.H.G., Whiten, A., & Perrett, D.I. (2001). Imitation, mirror neurons and autism. Neuroscience and Biobehavioral Reviews, 25, 287-295.
6 Frith, U. (1989). Autism: Explaining the Enigma. Blackwell Science.
7 Happé, F.G.E. (1996) Studying weak central coherence at low levels: children with autism do not succumb to visual illusions: a research note. Journal of Child Psychology & Psychiatry, 37, 873Ã–877.
8 Happé, F.G.E. (1999). Autism: Cognitive deficit or cognitive style? Trends in Cognitive Sciences, 3(6), 216-222.
9 Jolliffe, T., & Baron-Cohen, S. (1997). Are people with autism and Asperger syndrome faster than normal on the Embedded Figures Test?
Journal of Child Psycholology & Psychiatry, 38, 527–534.
10 Ring, H.A., Baron-Cohen, S., Wheelwright, S., Williams, S.C.R., Brammer, M., Andrew, C., & Bullmore, E.T. (1999). Cerebral correlates of preserved cognitive skills in autism: A functional MRI study of Embedded Figures Task performance. Brain, 122, 1305-1315.
11 Bemnetto, L., Pennington, B.F., & Rogers, S.J. (1996). Intact and impaired memory functions in autism. Child Development, 67(4), 1816-1835.
12 Blake, R., Turner, L.M., Smoski, M.J., Pozdol, S.L., & Stone, W.L. (2003). Visual recognition of biological motion is impaired in children with autism. Psychological Science, 14(2), 151-157.
13 Bertone, A., Mottron, L., Jelenic, P, & Faubert, J. (2003). Motion perception in autism: A "complex" issue. Journal of Cognitive Neuroscience, 15(2), 218-225.