Friday, February 29, 2008

Autism:a cognitive style and not a deficit

Continuing with the theme of my last post, I'll like to highlight an important review article by Happe, in which it is argued that Autism is a different cognitive style and not should not be thought in terms of underlying deficits, but that strengths be also recognized and given equal footing.

The major thesis of the article lies heavily on the 'Weak central coherence' theory of Autism, as per which the Autistics have a cognitive style dominated by local processing at the expanse of the gestalt and which claims that Autistics use too little of context in interpreting information/ percepts. There is a lot of data on which the above is based and I suggest that one read the TICS review in its entirety. For those who prefer snippets instead, here goes:

One current account of autism proposes that a different, rather than merely deficient, mind lies at the centre of autism. Frith, prompted by a strong belief that assets and deficits in autism might have one and the same origin, proposed that autism is characterized by weak ‘central coherence’. Central coherence (CC) is the term she coined for the everyday tendency to process incoming information in its context – that is, pulling information together for higher-level meaning – often at the expense of memory for detail. For example, as Bartlett’s classic work showed, the gist of a story is easily recalled, while the detail is effortful to retain and quickly lost6. Similarly, global processing predominates over local processing in at least some aspects of perception. This preference for integration and global processing also characterizes young children and individuals with (non-autistic) mental handicap who, unlike those with autism, show an advantage in recalling organized versus jumbled material. Indeed, recent research suggests that global processing might predominate even in infants as young as three months.

Frith has suggested that this feature of human information- processing is disturbed in autism, and that people with autism show detail-focused processing in which features are perceived and retained at the expense of global configuration and contextualized meaning. Clinically, children and adults with autism often show a preoccupation with details and parts, while failing to extract gist or configuration. Kanner, who named autism, commented on the tendency for fragmentary processing in relation to the children’s characteristic resistance to change; ‘...a situation, a performance, a sentence is not regarded as complete if it is not made up of exactly the same elements that were present at the time the child was first confronted with it’. Indeed, Kanner saw as a universal feature of autism the ‘inability to experience wholes without full attention to the constituent parts’, a description akin to Frith’s notion of weak CC.

Because weak CC provides both advantages and disadvantages,it is possible to think of this balance (between preference for parts versus wholes) as akin to a cognitive style – a style that might vary in the normal population. There might perhaps be a normal distribution of cognitive style from ‘weak’ CC (preferential processing of arts – for example, good proof reading), to ‘strong’ (preferential processing of wholes – for example, good gist memory). There is existing but disparate evidence of normal individual differences in local versus global processing, from infancy, through childhood43, and in adulthood. Sex differences have been reported on tasks thought to tap local versus global processing, although studies have typically confounded type of processing (local versus global) and domain (visuospatial versus verbal). The possibility of sex differences in coherence is intriguing in relation to autism, which shows a very high male to female ratio, especially at the high ability end of the autism spectrum. Might the normal distribution of coherence in males be shifted towards weak coherence and local or featural processing? Perhaps there is an area of increased risk for autism at the extreme weak coherence end of the continuum of cognitive style – individuals who fall at this extreme end might be predisposed to develop autism if unlucky enough to suffer the additional social deficits (impaired theory of mind) apparent in this disorder.

Preliminary results suggest that parents, and especially fathers, of children with autism show significantly superior performance on tasks favouring local processing: they excel at the EFT (Embedded Figure Task), at (unsegmented) block design, and at accurately judging visual illusions. They are also more likely than fathers in the other groups to give local completions to sentence stems such as, ‘The sea tastes of salt and..?’ (‘…pepper’). In all these respects they resemble individuals with autism, but for these fathers their detail-focused cognitive style is usually an asset, not a deficit. These results fit well with work by Baron-Cohen and colleagues, which showed that fathers of children with autism are fast at the EFT, and over-represented in professions such as engineering.

All this is consistent with this Blog's focus on Autism and Psychosis as opposite ends on a continuum of cognitive and social style.

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Wednesday, February 27, 2008

Autism: difference or disease?

There is an article in Wired Magazine arguing that autism is not a disease, but just a matter of difference and neurodiversity. It argues that the myth that almost 75% of Autistics are mentally retarded does not stand to scrutiny, but is perpetuated as we use measures of intelligence that are highly verbal in nature.

A cornerstone of this new approach — call it the difference model — is that past research about autistic intelligence is flawed, perhaps catastrophically so, because the instruments used to measure intelligence are bogus.

Mike Merzenich, a professor of neuroscience at UC San Francisco, says the notion that 75 percent of autistic people are mentally retarded is "incredibly wrong and destructive." He has worked with a number of autistic children, many of whom are nonverbal and would have been plunked into the low-functioning category. "We label them as retarded because they can't express what they know," and then, as they grow older, we accept that they "can't do much beyond sit in the back of a warehouse somewhere and stuff letters in envelopes."

The article focuses on the work of Dr. Mottron, who believes in the difference model and has researched on the strengths that Autistics may exhibit.

By the mid-1990s, Mottron was a faculty member at the University of Montreal, where he began publishing papers on "atypicalities of perception" in autistic subjects. When performing certain mental tasks — especially when tapping visual, spatial, and auditory functions — autistics have shown superior performance compared with neurotypicals. Call it the upside of autism. Dozens of studies — Mottron's and others — have demonstrated that people with autism spectrum disorder have a number of strengths: a higher prevalence of perfect pitch, enhanced ability with 3-D drawing and pattern recognition, more accurate graphic recall, and various superior memory skills.

The article goes on to discuss a recent paper that showed that autistics have the same level of intelligence- only that their intelligence is of a different kind: non-verbal.

Last summer, the peer-reviewed journal Psychological Science published a study titled "The Level and Nature of Autistic Intelligence." The lead author was Michelle Dawson. The paper argues that autistic smarts have been underestimated because the tools for assessing intelligence depend on techniques ill-suited to autistics. The researchers administered two different intelligence tests to 51 children and adults diagnosed with autism and to 43 non-autistic children and adults.

The first test, known as the Wechsler Intelligence Scale, has helped solidify the notion of peaks of ability amid otherwise pervasive mental retardation among autistics. The other test is Raven's Progressive Matrices, which requires neither a race against the clock nor a proctor breathing down your neck. The Raven is considered as reliable as the Wechsler, but the Wechsler is far more commonly used. Perhaps that's because it requires less effort for the average test taker. Raven measures abstract reasoning — "effortful" operations like spotting patterns or solving geometric puzzles. In contrast, much of the Wechsler assesses crystallized skills like acquired vocabulary, making correct change, or knowing that milk goes in the fridge and cereal in the cupboard — learned information that most people intuit or recall almost automatically.

What the researchers found was that while non-autistic subjects scored just about the same — a little above average — on both tests, the autistic group scored much better on the Raven. Two individuals' scores swung from the mentally retarded range to the 94th percentile. More significantly, the subset of autistic children in the study scored roughly 30 percentile points higher on the Raven than they did on the more language-dependent Wechsler, pulling all but a couple of them out of the range for mental retardation.

I, myself, have been arguing for a continuum model of abilities with Autism at one end and schizophrenia at the other end of cognitive thinking and sensory processing styles; so I am sympathetic to the above account of a difference model.

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Tuesday, February 19, 2008

Encephalon: New Season arrives

The new season of Encephalon has started at the Sharpbrains blog and this time addresses 24 questions to the US presidential candidates ala science debate 2008!

There are a variety of good posts there including discussions of free will and whether a trauma is relevant for PTSD ?

Have a look and contribute to further editions!!

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Wednesday, February 13, 2008

Encephalon: second innings to start with a bang!

Alvaro, at the Sharpbrains , has taken over the ownership of the brain sciences blog carnival Encephalon, and would be opening the second innings on the 18th of feb. He has just posted an announcement on Sharpbrains as to how to contribute. The rules and procedure remain the same. You need to send a mail to encephalonDOThostATgmailDOTcom (convert CAPS to special chars ).

I'm hopeful that we are going to see some interesting posts via this carnival. If you have written a neurosciences/ psychology related post in the past few weeks , do send them to the carnival.

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Monday, February 11, 2008

The Rat Park: Addiction and Environmental factors

I recently came across an article in the Walrus Magazine on the Rat Park. Basically a rat park is providing an enriched environment to the rats (both physical and social) as compared to the skinner box and then letting them self-administer the drugs of abuse like morphine. It was found that rats were not prone to addiction to these habit forming drugs , if they lived in an enriched environment.

The problem with the Skinner box experiments, Alexander and his co-researchers suspected, was the box itself. To test that hypothesis, Alexander built an Eden for rats. Rat Park was a plywood enclosure the size of 200 standard cages. There were cedar shavings, boxes, tin cans for hiding and nesting, poles for climbing, and plenty of food. Most important, because rats live in colonies, Rat Park housed sixteen to twenty animals of both sexes.

Rats in Rat Park and control animals in standard laboratory cages had access to two water bottles, one filled with plain water and the other with morphine-laced water. The denizens of Rat Park overwhelmingly preferred plain water to morphine (the test produced statistical confidence levels of over 99.9 percent). Even when Alexander tried to seduce his rats by sweetening the morphine, the ones in Rat Park drank far less than the ones in cages. Only when he added naloxone, which eliminates morphine’s narcotic effects, did the rats in Rat Park start drinking from the water-sugar-morphine bottle. They wanted the sweet water, but not if it made them high.

In a variation he calls “Kicking the Habit,” Alexander gave rats in both environments nothing but morphine-laced water for fifty-seven days, until they were physically dependent on the drug. But as soon as they had a choice between plain water and morphine, the animals in Rat Park switched to plain water more often than the caged rats did, voluntarily putting themselves through the discomfort of withdrawal to do so.

Rat Park showed that a rat’s environment, not the availability of drugs, leads to dependence. In a normal setting, a narcotic is an impediment to what rats typically do: fight, play, forage, mate. But a caged rat can’t do those things. It’s no surprise that a distressed animal with access to narcotics would use them to seek relief.

The article then goes on to address some of the politics behind funding and how Alexander could not secure funding and how he later tried to study the same phenomenon in humans.

Unable to secure funding, Alexander conducted most of his research in the library, where he gathered a mountain of evidence. A survey of Ontario households in 1987, for example, suggested that 95 percent of those who had ever tried cocaine were using it less than once a month. A 1990 survey conducted in the US found that crack cocaine, “the most addictive drug on earth,” was addicting only one user in a hundred. “Naturally, because scholars are scrupulous, I’ve had to try it [morphine] myself,” Alexander says. “It’s no big deal. You’re visibly lightened of pain and anxiety, and that’s mildly pleasant.” But he didn’t experience any urge to try it again. “I just wasn’t interested, and that’s the typical response.”

Then there are the thousands of American soldiers who became heroin addicts during the Vietnam War. In an unrivalled demonstration of the effect of setting, a 1975 survey found that 88 percent of them simply stopped using the drug when they left the war zone. Their experience has been recreated by millions of hospital patients who have received (and become physically dependent on) morphine for severe pain. If opioids are all they’re reputed to be, this practice should have produced legions of addicts. Instead, as researchers have discovered, once patients are no longer in physical distress, they can’t wait to quit the drug, go through the withdrawal period, and get on with their lives. It’s Rat Park’s “Kicking the Habit” experiment carried out on humans, with the same result.

In my view this is an important funding, that has been kept suppressed for a long time, but whose time has come now. We all know the beneficial effects of enriched environments and the harmful effects of stress (even social stress like placed in a lower social dominance hierarchy ) . In a similar experiment with primates it was found that those who were at the top of the social dominance hierarchy did not become addicted while those at the lowest level of hierarchy became addicting to stuff like cocaine and heroin.

Dominant animals had more D2 [dopamine receptor] activity than subordinates, but that was a consequence of their dominance, and not its cause [emphasis added]. Regardless of their D2 activity when kept individually, monkeys that became subordinate showed little change in their PET responses after they had been put into company. In the animals that became dominant, by contrast, D2 activity increased significantly… Like D2 activity, cocaine use was related to social status. Dominant animals found a preferred level, then stuck to it. Subordinates, though, seemed to need bigger and bigger fixes as time went on. That is a classic symptom of addiction… Propensity to addiction, in other words, is not a predisposition of the individual, but the result of social context.

All these data merit a rethink of addiction as a purely biological phenomenon and implores us to take a more environmental approach.

Hat tip: Neuroanthropology blog

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Friday, February 08, 2008

Autism / Psychosis: Agency and Joint Attention

A recent study by Tomosello's group indicates that children with autism, can help a stranger pick a pen (and thus can apparently infer goal and intentional states of others), but cannot indulge in co-operative behavior that may involve shared goals and shared attention.

As per Translating Autism blog:

This fresh-off-the-press article comes to us from Dr. Michael Tomasello’s group at the Max Planck institute in Germany. The authors present the results of two studies looking at helping and cooperation in children with autism. The first study compared 15 children with ASD (14 with Autism and 1 with PDD-NOS) with 15 children with other non-ASD developmental delays (40 months of age average). During this study the children were place in situations that either called for helping behaviors (such as picking up a pen that the researcher dropped and could not reach) or a similar situation that did not necessarily call for helping behaviors (such as when the researcher threw the pen on purpose and did not attempt to pick it up). Both groups (children with Autism and children with other developmental delays) showed more helping behaviors when placed in the situation that called for such behaviors. That is, when the experimenter was “trying” to reach an out-of-reach object, both groups were more likely to help than when the experimenter was not trying to reach for the object. The authors concluded that these behaviors showed that both groups understood the adult’s goals and were motivated to help her. In the second study, the same children were placed in situations that called for “cooperative” behaviors, such as a task requiring them to work with the researcher by simultaneously pulling at two cylinders to reach a toy. The results showed that children with autism were less likely than kids with other developmental delays to successfully complete the cooperation tasks. Furthermore, the children with autism were less likely to initiate additional attempts to complete the task when the task was interrupted. The authors concluded that, at least at this developmental period, children with autism seem to understand the social components of situations that call for “helping” behaviors and engage in helping behaviors, but only when such help does not require interpersonal cooperation. However, when cooperation is required to complete the task, these children are less likely to correctly engage with another partner, possibly because the unique “shared” component of cooperation. That is, cooperation requires shared goals, shared attention, and a shared plan of action, processes that seem to be affected in children with autism.

Here is the abstract of the Tomosello paper:

Helping and cooperation are central to human social life. Here, we report two studies investigating these social behaviors in children with autism and children with developmental delay. In the first study, both groups of children helped the experimenter attain her goals. In the second study, both groups of children cooperated with an adult, but fewer children with autism performed the tasks successfully. When the adult stopped interacting at a certain moment, children with autism produced fewer attempts to re-engage her, possibly indicating that they had not formed a shared goal/shared intentions with her. These results are discussed in terms of the prerequisite cognitive and motivational skills and propensities underlying social behavior

From the above it is clear that children with Autism lack shared attention: a pre-requisite for language and their language impediments may also be due to this fact. If we contrast this with Schizophrenia/ Psychosis ( and assuming they are at opposite ends) it is not hard to see that with too much shared goals/ intentions/ attention, one may likely confuse between one's own goals and those of others and in a joint scenario be more susceptible to delusions of control/ though insertion, wherein the shared space has become so vast that one seems to be controlled by the other or intruded by the other. thus , I propose that children susceptible to psychosis should show enhanced cooperating behavior indicating an overactive shared goals/ attention module.

Another interesting study I would like to discuss is the recent reporting of a dysfunctional 'self' module/model in a Trust game as compared to the 'other' module/ model. Here is how the Science Daily describes the Trust game that was used in the game.

In the trust game, one player receives an amount of money and then sends whatever amount he or she wants to the other player via computer message. The amount sent is tripled and the player at the other end then decides how much of the tripled amount to send back. The game has several rounds.

The 'self' module was identified as the brain areas (cingulate cortex) involved when making the decision to share the initial amount of money with another person. The 'other' module was defined as network region activated when the decision of the other player was revealed to them.

It was found that autistics showed lowered activity in the 'self' module. The authors construe this as evidence that they have a defective self concept.

"To have a good self concept, you have to be able to decide if the shared outcome is due to the other person or due to you," said Montague. "If people can't see themselves as a distinct entities at deeper levels, there is a disconnect."

I beg to differ. In my view the findings can be explained using the joint attention / goal/ outcome defect outlined above. Although I believe that their explanation that people with autism may have a diminished sense of self or Agency also makes intuitive sense and I have argued the same previously. I contrast that with the Psychotic case where one attributes too much agency- even to inanimate objects or animals for example. However, in this case a more parsimonious explanation can be that the autistics were not able to model the others goal as their own (the familiar simulation argument) and could not indulged in joint goal intention and thus failed to optimally use the 'self' module i/e failed to take whatever actions were needed for a co-operative and trustful behavior .

The Friths adequately sum that up:

In a preview in the journal Neuron, Chris and Uta Frith wrote, "This is an exciting result because it suggests that some mechanisms of social interaction are intact in these high-functioning cases. What is the critical difference between the self phase and the other phase? We believe that the simple distinction of self versus other is not adequate. "It involves higher-order mentalizing: you care what another person thinks of you, and even further, you care that the other person trusts you. You would not do this when playing against a computer. In autism there is no difference," wrote the Friths, who are at University College London.

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Wednesday, February 06, 2008

Russsinas have a richer discriminative experience of light and dark blue qualia

I have blogged extensively earlier regarding language, color and the sapir -whorf hypothesis. My position in the above is clear, I lean towards the sapir-whorf hypothesis and a mild form of linguistic determinism. Now a new study (which I had missed earlier) by Lera Boroditsky presents further corroborating evidence that language influences even such basic functions as color perception. As per their 2007 PNAS paper, Russians are better (more speedily) able to distinguish between the light blue and dark blue color in an objective color perception task, thanks to the fact that Russian has a different color term for dark blue and a different one for the light blue. It is an excellent paper and I present some excerpts from the introduction:

Different languages divide color space differently. For example,the English term ‘‘blue’’ can be used to describe all of the colors in Fig. 1. Unlike English, Russian makes an obligatory distinction between lighter blues (‘‘goluboy’’) and darker blues (‘‘siniy’’). Like other basic color words, ‘‘siniy’’ and ‘‘goluboy’’ tend to be learned early by Russian children (1) and share many of the usage and behavioral properties of other basic color words (2). There is no single generic word for ‘‘blue’’ in Russian that can be used to describe all of the colors in Fig. 1 (nor to adequately translate the title of this work from English to Russian). Does this difference between languages lead to differences in how people discriminate colors?

The question of cross-linguistic differences in color perception has a long and venerable history (e.g., refs. 3–14) and has been a cornerstone issue in the debate on whether and how much language shapes thinking (15). Previous studies have found cross-linguistic differences in subjective color similarity judgments and color confusability in memory (4, 5, 10, 12, 16). For example, if two colors are called by the same name in a language, speakers of that language will judge the two colors to be more similar and will be more likely to confuse them in memory compared with people whose language assigns different names to the two colors. These cross-linguistic differences develop early in children, and their emergence has been shown to coincide with the acquisition of color terms (17). Further, cross-linguistic differences in similarity judgments and recognition memory can be disrupted by direct verbal interference (13, 18) or by indirectly preventing subjects from using their normal naming strategies (10), suggesting that linguistic representations are involved online in these kinds of color judgments.

Because previous cross-linguistic comparisons have relied on memory procedures or subjective judgments, the question of whether language affects objective color discrimination performance has remained. Studies testing only color memory leave open the possibility that, when subjects make perceptual discriminations among stimuli that can all be viewed at the same time, language may have no influence. In studies measuring subjective similarity, it is possible that any language-congruent bias results from a conscious, strategic decision on the part of the subject (19). Thus, such methods leave open the question of whether subjects’ normal ability to discriminate colors in an objective procedure is altered by language.

Here we measure color discrimination performance in two language groups in a simple, objective, perceptual task. Subjects were simultaneously shown three color squares arranged in a triad (see Fig. 1) and were asked to say which of the bottom two color squares was perceptually identical to the square on top.

This design combined the advantages of previous tasks in a way that allowed us to test for the effects of language on color perception in an objective task, with an implicit measure and minimal memory demands.

First, the task was objective in that subjects were asked to provide the correct answer to an unambiguous question, which they did with high accuracy. This feature of the design addressed the possibility that subjects rely only on linguistic representations when faced with an ambiguous task that requires a subjective judgment. If linguistic representations are only used to make subjective judgments in ambiguous tasks, then effects of language should not show up in an objective unambiguous task with a clear correct answer.

Second, all stimuli involved in a perceptual decision (in this case, the three color squares) were present on the screen simultaneously and remained in full view until the subjects responded. This allowed subjects to make their decisions in the presence of the perceptual stimulus and with minimal memory demands.

Finally, we used the implicit measure of reaction time, a subtle aspect of behavior that subjects do not generally modulate explicitly. Although subjects may decide to bias their decisions in choosing between two options in an ambiguous task, it is unlikely that they explicitly decide to take a little longer in responding in some trials than in others.

In summary, this design allowed us to test subjects’ discrimination performance of a simple, objective perceptual task. Further, by asking subjects to perform these perceptual discriminations with and without verbal interference, we are able to ask whether any cross-linguistic differences in color discrimination depend on the online involvement of language in the course of the task.

The questions asked here are as follows. Are there crosslinguistic differences in color discrimination even for simple, objective, perceptual discrimination tasks? If so, do these differences depend on the online involvement of language? Previous studies with English speakers have demonstrated that verbal interference changes English speakers’ performance in speeded color discrimination (21) and in visual searching (22, 23) across the English blue/green boundary. If a color boundary is present in one language but not another, will the two language groups differ in their perceptual discrimination performance across that boundary? Further, will verbal interference affect only the performance of the language group that makes this linguistic distinction?

They then go on to discuss their experimental setup (which I recommend you go and read). Finally they present their findings:

We found that Russian speakers were faster to discriminate two colors if they fell into different linguistic categories in Russian (one siniy and the other goluboy) than if the two colors were from the same category (both siniy or both goluboy). This category advantage was eliminated by a verbal, but not a spatial, dual task. Further, effects of language were most pronounced on more difficult, finer discriminations. English speakers tested on the identical stimuli did not show a category advantage under any condition. These results demonstrate that categories in language can affect performance of basic perceptual color discrimination tasks. Further, they show that the effect of language is online, because it is disrupted by verbal interference. Finally, they show that color discrimination performance differs across language groups as a function of what perceptual distinctions are habitually made in a particular language.

They end on a philosophical note:

The Whorfian question is often interpreted as a question of whether language affects nonlinguistic processes. Putting the question in this way presupposes that linguistic and nonlinguistic processes are highly dissociated in normal human cognition, such that many tasks are accomplished without the involvement of language. A different approach to the Whorfian question would be to ask the extent to which linguistic processes are normally involved when people engage in all kinds of seemingly nonlinguistic tasks (e.g., simple perceptual discriminations that can be accomplished in the absence of language). Our results suggest that linguistic representations normally meddle in even surprisingly simple objective perceptual decisions.

To me this is another important paper that puts sapir-whorf hypothesis on the forefront. I would love to hear from those who do not endorse the spair-whorf hypothesis as to what they make of these results?

hat tip: Neuroanthropology blog.

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