Evidence for heightened Agency in Schizophrenia

I have been maintaining that Autism and Schizophrenia are opposites on a continuum and one dimension on which they differ is Agency , with autistics attributing too less agency to themselves (and others), while schizophrenics attributing too much agency to themselves (and others).

The case for people with ASD is fairly settled. They have deficits in theory Of Mind (ToM) and one mechanism by which this deficit seems to arise is via their attributing less agency to themselves as well as others.

For Schizophrenics too, it was speculated that they have problems with agency , but a clear illustration that they have an enhanced agency attribution device was not firmly established. This study, which dates back to 2003, in my opinion, establishes the fact that their is hyper-agency attribution (or hyper-self-menatlizing) in schizophrenics.

The study in question is one by Haggard et al , and it uses an experimental paradigm to illustrate that schizophrenics indeed have problems with self- agency attribution, and that too in the hypothesized direction.

Here is the abstract:

An abnormal sense of agency is among the most characteristic yet perplexing positive symptoms of schizophrenia. Schizophrenics may either attribute the consequences of their own actions to the intentions of others (delusions of influence), or may perceive themselves as causing events which they do not in fact control (megalomania).Previous reports have often described inaccurate agency judgments in schizophrenia, but have not identified the disordered neural mechanisms or psychological processes underlying these judgments.We report the perceived time of a voluntary action and its consequence in eight schizophrenic patients and matched controls.The patients showed an unusually strong binding effect between actions and consequences. Specifically, the temporal interval between action and consequence appeared shorter for patients than for controls. Patients may overassociate their actions with subsequent events, experiencing their actions as having unusual causal efficacy.Disorders of agency may reflect an underlying abnormality in the experience of voluntary action.

Now, let us pause and recollect that Chris Frith had postulated that the voluntary action mechanism in Scizophrenics is somewhat malformed and specifically there is a disconnect between intention attribution and voluntary action manifestation. He however had not clearly stated that there would be over-attribution of intention to voluntary actions. We all know that dopamine is associated with voluntary action (voluntary movements) and that baseline dopamine is in excess in schizophrenics. This paper ties things in together showing that excess dopamine secretion in basal ganglia and cortical areas may lead to greater biding between intentions and subsequent actions (consequences) and by this mechanism may lead to over-attribution of agency. Of course the paper doe snot establish this mechanism but just speculates on it as one of the possible mechanisms. It is also important to pause and note that schizophrenics have a jumping-to-conclusions bias and thus if an intention and action were more tightly bound (occurred in time in close proximity)_, then they are more likely to judge the two events to be related and the intention to cause the action.

Now let me get to the actual experiment. Haggard et al asked schizophrenics as well as matched controls to note subjective time (using Libets approach) when they decided to voluntarily press a computer key, and also subjective time when they first heard an auditory tone . The tone was presented 250 ms after their voluntary key press. As has been established earlier, and using controls in this experiment, people advance the key press in future (shift it towards future time from the exact time they actually pressed the key) so that subjectively the key press happens after some time form the objective key press and in the direction of the tone presentation. Thus, the effective subjective time between the key press and the tone is reduced. This binding between a voluntary action and its consequence , happens in normal individuals too, but in schizophrenics this happened significantly more in magnitude ans was dependent on two factors. first, like in normals , the voluntary key press was advanced in time towards the tone presentation, but this advance was significantly greater than in the case of controls. Secondly, the subjective auditory tone was sort of anticipated and shifted back in time towards the voluntary key press in schizophrenics. Thus, in schizophrenics, it seemed to them that the auditory tone had occurred prior to when it was actually presented. This lead to overall very significant reduction in subjective time experienced between the voluntary key press and the tone hearing, thus binding the two events strongly and leading to stronger agency inferred. to quantize the things a bit, in normal controls the voluntary key press was on the average occurring 26 ms from the actual key press, the auditory tone was heard 5 ms from the actual presentation and thus the subjective difference between the key press (intention) and tone (consequence) was 250-(26+5)= 239 ms. In schizophrenics, the key press was deemed to occur 60 ms after the actual key press, however most importantly the tone was not heard subjectively after its presentation, but was heard anticipatory 139 ms before its actual presentation, thus the actual perceived subjective time between the key press (intention) and the tone (consequence) was 250-60-139 = 51 ms only. Now , one can easily see, that if perceived subjective time between tow events is shortened in schizophrenia, then wont they end up falsely clubbing many coincidental things too together, because they seem to follow each other in close temporal proximity.

To appreciate the results, one needs to put these results in the broader context of what we know about agency in schizophrenics:

Previous laboratory studies have investigated agency using action attribution tasks. In these tasks, the patient is asked to perform an action, and is shown a visual image corresponding to that action, for example, a line drawn with a pen , a video of a hand making a manual posture , or a computerised image of a joystick moving. By introducing a mismatch between the performed action and the visual feedback, experimenters investigate the accuracy of attribution judgments. The subject has to attribute the viewed image either to an action he has just been instructed to make or to some other source. Interestingly, all these studies have found schizophrenics abnormally willing to attribute to themselves actions which in fact differ from the ones they performed. Thus, they are less sensitive than control subjects to spatial, temporal or kinematic mismatches between actions and visual feedback. The direction of these results points towards an excessive, rather than a reduced, sense of agency. Such results have been interpreted in the context of an internal forward model. Schizophrenic patients’ errors involve mostly over-attribution, implying a forward model with an unusually tolerant comparator.

Impaired judgement of agency can also be linked to the brain abnormalities underlying the disease. Agency involves forming a conscious mental association between one’s own intentional actions, and their consequences in the outside world. Thus, agency may be a conscious aspect of a more general system for instrumental or operant learning about environmental contingencies and rewards. Animal learning studies show that dopaminergic circuits, including the basal ganglia and medial forebrain are essential for associating actions with their effects, and for motivating behaviours. Brain imaging studies in man show that these same areas are active when a voluntary action produces a reward or other salient consequence . Moreover, these dopaminergic circuits are overactive in schizophrenia . Excessive dopaminergic activity might therefore explain abnormalities of conscious agency in schizophrenia, such as over-association between intentions and external events.

This is how they interpret their results:

More importantly, our schizophrenic patients seem to show an exaggerated version of the normal binding effect, or hyperbinding. These results could account for the findings of some action attribution experiments. Franck et al. asked patients and controls to move a joystick and then to observe their movements on a computer screen after a delay. The experimenters systematically varied the delay to investigate at what point the two groups ceased to accept the observed action as their own. Control subjects detected the temporal discrepancy between their action and the image with delays of around 100–150 ms. Schizophrenic subjects were much more tolerant, and accepted the viewed action as their own even for delays of 300 ms. Overall, the detection threshold for the relevant action was increased by about 150–200 ms for the patients compared to the controls. This value can be compared to the 180 ms difference between our patients and controls in the implied perceptual duration of the interval between action and tone.

The direction of the attribution effect is important: schizophrenics over-attributed events to their own agency. Our data suggests that schizophrenic patients have unusually strong associations between conscious representations of action and consequence. Thus, they might bind action and viewed image across the substantial delay periods imposed in the Franck et al. experiment, and be unaware of the artificially-induced lag between these events. There may be a critical period in which to perceive the consequence of an action. Actions and events falling in this period may be perceptually bound. A deficit in setting the duration of this critical period in schizophrenics could contribute to the shifts we found in their subjective temporal experience. This view would interpret abnormal conscious experience in schizophrenia as a problem in predicting the consequences of one’s own actions. Further work could investigate whether temporal analysis in schizophrenic patients is defective only when concerning their own actions, or also when observing actions made by others.

I am thrilled as usual and predict that if the same experimental paradigm is used with Autistic, then they will show very little or no forward movement of subjective time between their actual voluntary key-press and the subjective feel of when they decided to press the key. Also, there would be no anticipatory backwards movement of subjective time for when the tone was heard. Thus, Autistic would perceive the time gap as 250 ms only, or may even perceive the time to be more than 250 ms depending ion whether they move the voluntary key press subjective time back in time. No matter what they should show lesser binding between the intention (if they can form one) and consequence.

Haggard P, Martin F, Taylor-Clarke M, Jeannerod M, Franck N. (2003). Awareness of action in schizophrenia Neuroreport, 14 (7), 1081-1085

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Brain Awareness Week: March 16-22, 2009

Dana foundation organises International Brain Awareness Week (BWA) each year and this year I have partenered with them and wish to do something online during that week to raise brain awareness. I would request all my blog friends to do atleast a blog swarm related to brain awareness during that time. Meanwhile I'll keep it a surprise as to what I plan to do in that week!

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Cultural differences are Vodoo correlations: I beg to differ

Normally, I am delighted to read a new Ed Yong NERS blog post, and this article not only was published in New Scientist, but was also whole heartedly endorsed by Vaughan , again a person I admire the most.  Yet, I cannot hide my dismay over the fallacies that Ed commits and the muddled and biased thinking he displays- I can admire the moralistic stand from which he tries to interpret the recent findings with the conclusion that "But instead of dividing the world along cultural lines, we might be better off recognising and cultivating our cognitive flexibility." and I whole heartedly agree with that conclusion, but one need not nullify cultural differences to achieve the same objective of more cultural/ethnic tolerance and proactive re-wiring of what may be 'human / individual/ cultural nature'.

So, instead of dwelling on the moralistic aspect of the whole debate, let me get to the science part directly. Some of it may seem nit-picking, but others have profound implications.

AS A SPECIES, we possess remarkably little genetic variation, yet we tend to overlook this homogeneity and focus instead on differences between groups and individuals.

The first fallacy Ed commits is to implicitly link any individual / group differences with genetic variation. Genetic variation need not be,and is not,the be-all and end-all of individual / group differences. Let us focus on an individual trait like intelligence or say the personality dimension of neuroticism for an individual for the rest of this article and we can easily extend the arguments to other individual/ group differences. It is standard practice nowadays,to admit the crucial role of epigenetics, development, social environment or Nurture along with Nature to explain any complex phenomenon like Intelligence or Neuroticism. Thus while my IQ or temperament may be partly inherited (inherited again does'nt mean genetics alone, it includes shared environment factors), it is also partly under the influence of non-shared environmental factors and partly expressed uniquely for each individual depending on idiosyncratic individual factors or random variation. Thus, some of the individual differences in two persons for intelligence/ neuroticism will be due to genetics, but most of it would be due to environmental influences(including social/ cultural factors) and some of it would be 'undetermined' by either genetics or environment, but be random/due to luck/chance/history factors.

Perhaps Ed chose a wrong opening line, but that doesn't negate his thesis, or does it? We'll get to that , but remember that Personality psychology based on studying both individual differences , as well as finding human universals, has a long tradition and is a worthy field of study- if only because personality is not a myth- individual differences exists , are consistent and can be reliably assessed and have profound implications for our day-to-day interaction, or in more clinical settings.

Before I proceed let me first list my points of agreements- I agree with Ed that media always sensationalizes findings and stereotypes the cultures involved, sometimes overextending or over interpreting the actual study findings, there is no such thing as an 'Eastern' and a 'Western' culture- I'll be more happy talking about nation-state based cultures like the Indian culture, the Chinese culture, the Japanese culture and the American culture; I agree that studies have only looked at China , Japan, Us and some western countries and generalized and caricatured it as Eastern and Western Culture; that there is an either-or dichotomy between Analytical and holistic thinking styles - but they are more on a continuum. Now to points of disagreements.

Psychologists have conducted a wealth of experiments that seem to support popular notions that easterners have a holistic world view, rooted in philosophical and religious traditions such as Taoism and Confucianism, while westerners tend to think more analytically, as befits their philosophical heritage of reductionism, utilitarianism and so on. However, the most recent research suggests that these popular stereotypes are far too simplistic. It is becoming apparent that we are all capable of thinking both holistically and analytically - and we are starting to understand what makes individuals flip between the two modes of thought.

A study that shows that we are capable of both analytical and holistic mods of though does not negate the fact that their could still be important and significant individual/group diffrences for the same. Consider Neuroticsm- if someone, in particular, and we in general, are capable of exhibiting behavior/ emotional states that are the opposite of characteristic neurotic traits, it doesn't negate the fact that one can still have persons who exhibit abnormally high levels of Neuroticism. Nowhere is it claimed that someone with high trait neuroticism cannot display flexibility under proper environmental conditions- or that the behavior is totally independent of the situation- we gain go back to Miscels debate of how much situation and how much traits are responsible for behavior- but the fact of cognitive flexibility does not negate the existence of stable traits or tendencies. Consider a low IQ person- he may display intelligence under some situations and not display intelligence under other situations - that cognitive flexibility would not negate the fact that he has low intelligence in general. We may also understand the factors that lead to more intelligent behaviors and be able to manipulate his behavior to display state intelligence- still that wont negate his low trait intelligence. So the assertion that cognitive flexibility means no individual/ cultural differences is pure wishful thinking. Similarly the fact that state differences can be easily created and manipulated does not lead to automatic negation of trait differences. I can easily create the state anxiety in Ed Yong as he sees his article criticized severally, but the fact that I can easily manipulate and understand a neurotic state, doesn't say anything about the existence or non-existence of a neurotic trait or tendency.

Time and again, studies like these seem to support the same basic, contrasting pattern of thought. Westerners appear to perceive the world in an analytic way, narrowing their focus onto prominent objects, lumping them into categories and examining them through logic. Easterners take a more holistic view: they are more likely to consider an object's context and analyse it through its changing relationships with its environment.

I wont generalize to Westerners or Easterners, but definitely this does say something about the existence of an anayltical and holistic thinking style trait, which exists on a continuum, is highly correlated to 'cultures' and is thus a group trait, and a dimension on which some cultures may display extreme values. If studies have consistently supported and found that US culture leads to extremes of analytical tendencies while Chinese/Japanese culture ingrained people lean towards holistic style of thinking, why deny the fact. Is it because of a misplaced notion that if groups/ cultures differ it means one is 'better' than other- what about Neuroticism- is low (trait) neuroticism always beneficial and high (trait) neurtocism always bad. Not anymore- Read 'Personality' by Nettle for a quick overview but the growing consensus is that the extremes of traits are good under particular environmental conditions and a little variation against a continuum foolproofs one against future unpredictable environmental catastrophes. Extremes of traits can also be a result of adaptation to different environmental niches. So case settled- group/cultural differences on at least one important dimension fo analyitcal/ holistic thinking do exist.

For a start, the simplistic notion of individualistic westerners and collectivist easterners is undermined by studies designed to assess how people see themselves, which suggest that there is a continuum of these traits across the globe. In terms of individualism, for example, western Europeans seem to lie about midway between people in the US and those in east Asia.

Ed, what are you getting to here. Individualistic 'US'ers and collectivist Chinese are perfectly compatible with existence of Europeans who do lie midway. To go back to Neuroticim, the fact that some are Neurotic, while others are calm is nowhere in contradiction to the existence of some people who lie midway on this dimension and do not show any extremes.If the point was that analytical/ holistic is not categorical but dimensional point well taken!

So it's not all that surprising, perhaps, that other studies find that local and current social factors rather than the broad sweeps of history or geography tend to shape the way a particular society thinks. For example, Nisbett's group recently compared three communities living in Turkey's Black Sea region who share the same language, ethnicity and geography but have different social lives: farmers and fishers live in fixed communities and their trades require extensive cooperation, while herders are more mobile and independent. He found that the farmers and fishers were more holistic in their psychology than herders, being more likely to group objects based on their relationships rather than their categories: they preferred to link gloves with hands rather than with scarves, for instance (Proceedings of the National Academy of Sciences, vol 105, p 8552). A similar mosaic pattern of thought can be found in the east. "Hokkaido is seen as the Wild West of Japan," says Nisbett. "The citizens are regarded as cowboys - highly independent and individualistic - and sure enough, they're more analytic in their cognitive style than mainland Japanese."

Why has it always to be an either-or. Ed agrees that local and social factors are important, so at least he agrees that cultural/environmental factors are important and lead to group trait differences. His argument is that within-group variation is more than between-group variation (if one considers a culture as a group and the 'local groups, as individuals belonging to that bigger group) so it doesn't make sense of talking about differences in cultural mean values. I don't buy that. This argument has often been applied to ethnic/ racial IQ differences issues etc., and I believe that one should not deny facts based on their political or moral ramifications. Just like there are differences in average heights of chinese and americans, though the mean difference between chinese and american heights may be less than the variation exhibited in chinese or american society with respect to height, still it makes sense to say that on an average chinese are of lesser height than americans. This doesn't sound racist, it is a fact. Same holds true for other differences like IQ or in this case the average holistic/analytical thinking displayed by a culture.The fact that there is variation within the culture does not negate differences in mean values between cultures.

Is it time we moved beyond simplistic notions of eastern and western psychology? Daphna Oyserman from the University of Michigan in Ann Arbor certainly thinks so. She is not happy invoking history to explain modern human behaviour. "We can't test if history mattered," she says. "But we can test how contexts can evoke one or other mindset."

Why not history- just based on the personal comfort factor? now that it is established that cultures differ in holistic/analytical dimension, one needs to find out why. Again, the effect may be inherited (and thus partly genetic) or it may be learned and due to non-shared environmental factors- different local and geographic conditions to which the cultures are currently exposed. To endorse one extreme of non-shared environmental influences(based n personal comfort levels) as paramount and to rubbish any suggestion of influence of shared environmental factors (which in this case is culture itself as it provides the cultural and social context in which the group develops)or even genetics is to me an extremely stupid and outdated stand. History (or the then non-shared environment like the intensive agriculture of chinese) has influenced the cognitive style and the cognitive style gets ingrained in cultural traditions. These cultural traditions in turn provide the shared environment in which the culture develops. Also , people who display more holistic/ analytical style in a particular culture, may be culturally selected for, and it would not be surprising, if the favored trait gets fixed in the genetic code by cultural selection of that trait as individuals having that trait will be more successful and this would get fixed in the population as a whole. Thus, the group differences on cognitive style trait could be inherited (due to genes and shared cultural traditions) and also may be learned a new (response to novel non-shared local conditions) .

This experiment suggests that while the psychology of westerners may be superficially distinct from easterners, when social isolation is an issue there is little difference between the two. In fact, Oyserman's analysis of 67 similar studies reveals just how easily social context can change the way people think. For example, psychologists have "primed" east Asian volunteers to adopt an individualistic mode of thought simply by getting them to imagine playing singles tennis, circling single-person pronouns or unscrambling sentences containing words such as "unique", "independence" and "solitude". In many of the experiments volunteers from a single cultural background - be it eastern or western - show differences in behaviour as large as those you normally get when comparing people from traditionally collectivist and individualist cultures

One has to pause and ask where does 'social isolation' arise from if not a cultural tradition. If Chinese culture makes one feel more socially isolated and thus constantly in need of reaffirming relationships, than is that not a cultural difference - maybe we have narrowed it down to one important cultural tradition that leads to inheritability of thinking style, but still the cultures are different in important ways. Also, Experiments showing that priming can cause a lean towards a tendency nowhere prove that there are no group differences. Priming experiments have shown that when primed with old age related terms people walk slowly- does this negate the fact that young people are young, old people are old and there is whale of a difference in the average energy or walking speed of an old person and a young person. Should we conclude that age is a myth and that age is irrelevant to the average energy or time taken to walk a particular stretch!

The ease with which priming can alter our modes of thought makes it very unlikely that a penchant for either analytic or holistic thinking stems from deep-seated differences in the brains of westerners and easterners. Instead, it seems that the cultural context in which we grow up simply gives us more practice in thinking about the world in a particular way. "Everyone can think both ways, but on average, people tend to do more of one than the other," says Oyserman.

Sorry again. We can all be primed to display more intelligent behavior and our modes of thinking (creative or detail oriented) can be altered and manipulated, still people are looking (and have found some lateralization differences) for brain differences in these modes of thinking and like every phenomenon there is bound to be brain differences involved.(No I'm not endorsing the right-brained/ left-brained myth, but saying that creative and detail oriented thinking have no neurological basis to me seems wrong. Also, I'm glad that at last it is acknowledged that cultural practices in which we grow up gives us more practice/ exposure to a particular thinking style and lead to differences. Why should learning not lead to brain differences(remember plasticty 101) but genetics do I fail to understand. Also, remember critical developmental periods. It may be that there is a critical period in which this holistic/analytical thinking style gets fixed and that causes a long-lasting effect. Consider language- what language, and any language at all, that the child learns is dependent on correct exposure during critical developmental time; one can learn foreign languages later also , but with considerable effort and not as naturally as a child does. The story with holistic/analytical thinking style may be the same. One may develop this trait duirng a critcial developmental window and although manipulable it may not be totally non-hardwired.

Brain imaging supports this. In an experiment that involved subjects looking at a series of squares with lines in them, Trey Hedden from the Massachusetts Institute of Technology found that in east Asians the areas of the brain involved in focusing attention worked harder if they had to identify lines of the same length regardless of the surrounding squares - an "absolute" task that requires you to focus on an object regardless of its context. But with Americans the same brain areas were working harder to identify lines whose sizes varied proportionally with their squares - a "relative" judgement where context is key (Psychological Sciences, vol 19, p 12). In other words, people had to think harder to perform tasks outside their cultural comfort zone. The brain uses the same mental machinery to solve complex tasks, but cultural differences can affect how well trained these areas are.

No it doesn't, Haven't read the original studies, but from your discussion the areas involved are those relating to focusing attention- I believe it is common sense that you would focus more attention on a task that is not ingrained and is novel.What about other brain areas specific to the task. Were there differences in brain activation related to holistic/ analytical thinking. Was there some lateralization effect?

What is clear is that the minds of east Asians, Americans or any other group are not wired differently. We are all capable of both analytic and holistic thought. "Different societies make one option seem to make the most sense at any given moment," says Oyserman. But instead of dividing the world along cultural lines, we might be better off recognising and cultivating our cognitive flexibility. "There are a lot of advantages to both holistic and analytic perception," says Nisbett. In our multicultural world it would benefit us all if we could learn to adopt the most appropriate mode of thought for the situation in which we find ourselves.

No It is not at all clear that the brains are not wired differently. I believe there should be small differences, but based on the flexibility shown by people in switching from one style to another one can use plasticity and practice to re-wire the brain. Whether that re-wiring is required, or cultural social engineering is required would depend on whether one considers extremes maladaptive or just adaptive responses occupying particular niches. To deny differences outright is to deny the truth and perhaps lead to the fallacy of thinking everyone thinks like oneself. To understand differences is a first step towards greater tolerance and understanding. Hope I make sense.

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Linguistic effects on unconscious color perception

The post headline may seem an oxymoron , but it is indeed possible to perceive colors unconsciously. How do we know that someone has perceived a color, when he doesn't report the qualia. We do so by measuring the effects on subsequent behavior. Consider subliminal priming. Consider a subliminal stroop test, in which color patches are presented subliminally and then color lexical terms are presented consciously in neutral (say black) ink. I'm sure with this subliminal modified stroop test one could still get a color and lexical term interaction effect; the point is that color , when not perceived, may still influence subsequent behavior.

The experimental paradigm in this PNAS article did not go so far, but restricted itself to color stimuli that was not attended to; that is, the color was indeed perceived, but it was not attended to (the task involved attention to form rather than color) and so as the color was not attended to, they presumed that the effects that the color information would have on behavior would be completely unconscious. I'm not convinced, but that doesn't invalidate their otherwise very beautiful study that once again provides strong evidence for the milder version of the Sapir-Whorf hypothesis, at least as it relates to categorical color perception. 

Now, I have written previously about Sapir- Whorf hypothesis in general,  and in particular about the ability of Russians( who have two separate terms for light and dark blue) to visually discriminate between light and dark blue significantly better than their English counterparts, thanks to their rich color lexicon; so this new study that found that Greek-natives (who also have different lexical terms for light and dark blue) were superior to English-natives in terms of discriminating categorical color perception for light and dark blue color, did not come as a surprise or seemed ground-breaking; but there are important differences both in terms of the procedures used and the processes involved.

This study, works at pre-attentive level, uses physiological measures like ERP (they studied the vMMN - visual Mismatch Negativity) to determine whether the color stimuli had differential effect even at pre-attentive perception and thus provides independent evidence for the effect of Language on color perception. I'll now quote from the abstract and discussion section:

It is now established that native language affects one’s perception of the world. However, it is unknown whether this effect is merely driven by conscious, language-based evaluation of the environment or whether it reflects fundamental differences in perceptual processing between individuals speaking different languages. Using brain potentials, we demonstrate that the existence in Greek of 2 color terms—ghalazio and ble—distinguishing light and dark blue leads to greater and faster perceptual discrimination of these colors in native speakers of Greek than in native speakers of English. The visual mismatch negativity, an index of automatic and preattentive change detection, was similar for blue and green deviant stimuli during a color oddball detection task in English participants, but it was significantly larger for blue than green deviant stimuli in native speakers of Greek. These findings establish an implicit effect of language-specific terminology on human color perception.

This study tested potential effects of color terminology in different languages on early stages of visual perception using the vMMN, an electrophysiological index of perceptual deviancy detection. The vMMN findings show a greater distinction between different shades of blue than different shades of green in Greek participants, whereas English speakers show no such distinction. To our knowledge, this is the first demonstration of a relationship between native language and unconscious, preattentive color discrimination rather than simply conscious, overt color categorization.

To conclude, our electrophysiological findings reveal not only an effect of the native language on implicit color discrimination as indexed by preattentive change detection but even electrophysiological differences occurring as early as 100 ms after stimulus presentation, a time range associated with activity in the primary and secondary visual cortices (22). We therefore demonstrate that language-specific distinctions between 2 colors affect early visual processing, even when color is task irrelevant. At debriefing, none of the participants highlighted the critical stimulus dimension tested (luminance) or reported verbalizing the colors presented to them. The findings of the present study establish that early stages of color perception are unconsciously affected by the terminology specific to the native language. They lend strong support to the Whorfian hypothesis by demonstrating, for the first time, differences between speakers of different languages in early stages of color perception beyond the observation of high-level categorization and discrimination effects strategically and overtly contingent on language specific
distinctions.

I think this fits in with predictive models of perception, wherein, earlier stages of visual processing, that are unrelated to color discrimination, may still be primed by color information that one has obtained earlier and has processed pre-attentively. I, as always , am excited by this proof of whorfian hypotheses.

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An online personality guessing experiment

I came to know of You Just Get Me experiment today, courtsey PsychCentrals post on the top 10 online psychology experiments .

In a nutshell, the site lets you guess the personality of a person based on clues he provides. In my case the public clues I have provided are my photograph and my facebook profile. Now, as a fun experiment, I'll request all my readers to go to that site and try to guess my personality from these , as well as additional clues you might have got following my blogging practices and habits. Its bound to be fun and I believe the questionnaire has correctly guessed my personality (OCEAN based) and I have a separate application on facebook that profiles my personality (please do not take a sneak peak at it to guess my personality) and I found that the two personality characterizations do corroborate each other.

So, please go ahead and guess me; and of course if yopu like put some data on the site for your personality analysis too. Go to this link to guess my personality.

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Encephalon #64 up at the Neurocritic

The 64th edition of Encephalon is up at the Neurocritic and has been exceptionally well presented. Neurocritic embeds all the articles in context, sometimes linking to other external sources, and also providing a seamless flow between the varied topics that are covered. The articles themselves are very good, and include submissions from some new blogs other than the usual suspects.A couple of my favorites include a construal level-procrastination linkage study and a DAT-KO mice couldn't get high on cocaine study. There is more at the source, so head over to there.

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Support for the Aberrant Salience hypothesis of Psychosis

Last week I wrote about the aberrant salience theory of psychosis, and luckily, this week itself a new study has surfaced that corroborates that theory with some preliminary evidence.


Thanks to BPS research digest, I have come across this open source research article in Psychological Medicine, that has found evidence for the aberrant salience hypothesis.

What Rosier et al did was to administer a Salience Attribution Test to both patients with Schizophrenia and normal controls, and to look for differences in the adaptive and aberrant salience. It is important to realize that most of the patients were medicated on anti-psychotics, and as per the theory advocated by Shitij Kapur, the anti-psychotics would dampen the normal adaptive salience too as psychosis is due to hyper reactivity of dopamine system and anti-psychotics are supposed to work by attenuating that behavior. More specifically, the predictions were:

It has been hypothesized that dopamine antagonists reduce both adaptive and aberrant salience, and that in the absence of effective treatment patients with schizophrenia exhibit aberrant salience (Kapur, 2003). Therefore, our first prediction was that that medicated patients with schizophrenia would exhibit reduced adaptive salience relative to controls, representing an undesirable side-effect of anti-psychotic medication. Our second prediction was that medicated patients with schizophrenia would exhibit equivalent aberrant salience to controls, representing the beneficial effect of anti-psychotic medication, which is hypothesized to normalize aberrant salience from a previously elevated level (Kapur, 2003). Our third prediction was that those patients with persistent positive symptoms, in whom medication is not entirely effective, would exhibit greater aberrant salience than patients without positive symptoms. Our fourth prediction was that in the controls, individual differences in aberrant salience would be related to the personality trait of schizotypy, considered to be an index of psychosis proneness (Chapman et al. 1994; Claridge, 1994; Stefanis et al. 2004).

All of their predictions were supported by the test results. The SAT paradigm is really simple and depends on reaction time measures following CS+ and CS-; with CS+ reaction times quantifying adaptive salience and CS- reaction times quantifying aberrant salience attribution. Read the methods section for more on the SAT.

Interestingly in patients, those with persisting delusions as well as those high on Negative symptoms exhibited higher aberrant salience as compared to patients/ controls without any delusional symptoms.Also, in controls the introverted anhedonia subscale of schizotypy correlated signficantly with the aberrant salience, thus indicating a role for negative symptom formation/ explanation too as apart of the aberrant salience. This is how the authors interpret their findings:

Aberrant salience and positive symptoms of schizophrenia

One explanation of increased aberrant salience in patients with positive symptoms concerns aberrant dopamine signalling. Contemporary accounts of reward learning suggest that phasic dopamine firing codes reward prediction errors (Schultz et al. 1997), for example, those arising from temporal difference models of reinforcement learning (Dayan & Balleine, 2002). Such models elegantly account for changes in both the firing patterns of ventral tegmental area dopamine neurons in monkeys (Schultz, 1997), and ventral striatal responses in humans (Pessiglione et al. 2006; Seymour et al. 2007), as reward-learning progresses. If phasic dopamine release signals reinforcement prediction errors, any large stochastic fluctuation in dopamine release may disrupt learning about stimulus–reinforcement associations, generating a state in which motivational salience could be misattributed to neutral stimuli, or what might be termed a ‘false-positive’ phasic dopamine signal; such events have been proposed to result in positive symptoms (Kapur, 2003).
In the present study, patients for whom medication had effectively eliminated positive symptoms actually exhibited significantly less aberrant salience than controls, supporting the hypothesis that the beneficial effects of antipsychotic medications on positive symptoms are related to their ability to dampen-down aberrant salience (Kapur, 2003). However, independent of symptoms at the time of testing, the patients with schizophrenia exhibited significantly less adaptive salience than controls. Antipsychotic medication has long been considered to exacerbate negative symptoms in schizophrenia, which may be related to reduced adaptive salience [see discussion below and Schooler (1994) ]. Our findings support the suggestion of Kapur (2003) that this may be a necessary corollary to the beneficial effect of antipsychotic medication on positive symptoms.

Previous studies suggest that antipsychotic medication does not necessarily normalize abnormal dopamine signalling in psychotic patients. For example, functional neuroimaging studies have shown dopamine dysregulation in both medicated and unmedicated patients (Hietala et al. 1995; Abi-Dargham, 2004; McGowan et al. 2004). Therefore persistent symptoms in medicated patients might still be related to aberrant salience. Furthermore, the only other study investigating stimulus–reinforcement learning for appetitive outcomes in psychosis found that both medicated and unmedicated patients responded more quickly to a CS− than controls, a finding interpreted as aberrant salience (Murray et al. 2008). This study also reported that patients exhibited reduced haemodynamic correlates of reward prediction errors in the ventral striatum relative to controls, consistent with other findings in medicated patients (Juckel et al. 2006; Jensen et al. 2008). Nevertheless it will be important to confirm our findings in unmedicated patients.

Aberrant salience and negative symptoms of schizophrenia

Although positive symptoms were associated with increased aberrant salience, our data also suggest a link between aberrant salience and negative symptoms. Aberrant salience correlated not only with negative symptoms in the patients, but also with O-LIFE introvertive anhedonia, which relates to reduced interest and social withdrawal, in the controls. If dopamine transmission is dysregulated in psychosis (Abi-Dargham, 2004), it is possible that ‘false negatives’ in the phasic dopamine signal might occur, i.e. a reinforcement-related stimulus fails to elicit a sufficiently large phasic dopamine response. False negatives would decrease the value of motivationally salient stimuli, possibly leading to symptoms such as avolition, apathy and social withdrawal. Consistent with this explanation, other studies that investigated responses to emotionally salient images in medicated patients with schizophrenia reported decreased responding for (Heerey & Gold, 2007) and ventral striatal responses to (Taylor et al. 2005) positive emotional stimuli relative to controls.

This explanation is also consistent with data from a functional magnetic resonance imaging study investigating the effects of d-amphetamine on reward processing in healthy volunteers. Knutson et al. (2004) found that amphetamine administration paradoxically decreased the magnitude of phasic ventral striatal haemodynamic responses in response to a CS+ that signalled reward (i.e. increasing the potential for a false negative). In the same study, amphetamine administration caused significant phasic haemodynamic responses in the ventral striatum following CS+ that signalled potential monetary loss, an effect that was absent under placebo, possibly reflecting a loss of specificity of dopamine signalling (i.e. increasing the potential for a false positive). The aberrant salience model might therefore explain both positive and negative symptoms by appealing to a common neurobiological mechanism, namely a loss of signal:noise ratio in the mesolimbic dopamine system, possibly as a result of increased tonic dopamine activity (Grace, 1991; Winterer & Weinberger, 2004).

I believe they are on to something, but the explanation for negative symptoms is still not fully fleshed out or convincing. and of course one has to remember that these results are juts with 20 patients so need to be replicated before being put to use/ accepted as orthodoxy.

J. P. Roiser, K. E. Stephan, H. E. M. den Ouden, T. R. E. Barnes, K. J. Friston, E. M. Joyce (2008). Do patients with schizophrenia exhibit aberrant salience? Psychological Medicine, 39 (02) DOI: 10.1017/S0033291708003863

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On Reading Darwin

12 th of February was Darwin day, and I decided to study an original text of Darwin to honor the occasion. I chose the 'Expression of emotions in Man and animals' as my first text as I am familiar with the work of Paul Ekman and have had a deep fascination with the subject and wanted to find out how much Darwin had anticipated and got right in his times.I have only read the introduction and the first chapter till now, but am surprised at the level of modernity visible in Darwin's analysis.

Of course Darwin takes an evolutionary view on the subject and is also cognizant of the subtleness of the entire field.

He who admits on general grounds that the structure and habits of all animals have been gradually evolved, will look at the whole subject of Expression in a new and interesting light.

The study of Expression is difficult, owing to the movements being often extremely slight, and of a fleeting nature. A difference may be clearly perceived, and yet it may be impossible, at least I have found it so, to state in what the difference consists. When we witness any deep emotion, our sympathy is so strongly excited, that close observation is forgotten or rendered almost impossible; of which fact I have had many curious proofs. Our imagination is another and still more serious source of error; for if from the nature of the circumstances we expect to see any expression, we readily imagine its presence. Notwithstanding Dr. Duchenne's great experience, he for a long time fancied, as he states, that several muscles contracted under certain emotions, whereas he ultimately convinced himself that the movement was confined to a single muscle.

He then lists the various ways he plans to get to universal features of emotional expressions. These involve using questionnaires given to various anthropologists to discover if the emotions are expressed in a similar fashion all over the world ;and the study of infants and insane as they may have unadulterated / extreme emotional expressions respectively. He also briefly touches upon the usefulness of studying emotional expressions as depicted by Masters in painting in sculpture but finds the method wanting. Lats , but not the least, he studied emotional expression in other animals and treated emotional expression as a continuum.

Sixthly, and lastly, I have attended. as closely as I could, to the expression of the several passions in some of the commoner animals; and this I believe to be of paramount importance, not of course for deciding how far in man certain expressions are characteristic of certain states of mind, but as affording the safest basis for generalisation on the causes, or origin, of the various movements of Expression. In observing animals, we are not so likely to be biassed by our imagination; and we may feel safe that their expressions are not conventional.

He then lists the three basic principles of emotional expressions. I list them verbatim.

I. _The principle of serviceable associated Habits_.--Certain complex actions are of direct or indirect service under certain states of the mind, in order to relieve or gratify certain sensations, desires, &c.; and whenever the same state of mind is induced, however feebly, there is a tendency through the force of habit and association for the same movements to be performed, though they may not then be of the least use. Some actions ordinarily associated through habit with certain states of the mind may be partially repressed through the will, and in such cases the muscles which are least under the separate control of the will are the most liable still to act, causing movements which we recognize as expressive. In certain other cases the checking of one habitual movement requires other slight movements; and these are likewise expressive.

II. _The principle of Antithesis_.--Certain states of the mind lead to certain habitual actions, which are of service, as under our first principle. Now when a directly opposite state of mind is induced, there is a strong and involuntary tendency to the performance of movements of a directly opposite nature, though these are of no use; and such movements are in some cases highly expressive.

III. _The principle of actions due to the constitution of the Nervous System, independently from the first of the Will, and independently to a certain extent of Habit_.--- When the sensorium is strongly excited, nerve-force is generated in excess, and is transmitted in certain definite directions, depending on the connection of the nerve-cells, and partly on habit: or the supply of nerve-force may, as it appears, be interrupted. Effects are thus produced which we recognize as expressive. This third principle may, for the sake of brevity, be called that of the direct action of the nervous system

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The first principal is easy to understand. It basically states that facial expression etc are associated with mental emotional states and do so by way of habit formation or association. Now, this should not exclude instinctual emotional expressions like smiling as they become fixed by the action of evolution.

The second principle has had only some relatively moderate success. I remember a recent study claiming that Fear and Disgust had opposite effects on facial muscle movements such that Fear led to movements (like broadening of eyes/ dilation of pupils)that allowed more information/material to be ingested; while disgust led to constriction of nose, eye, mouth etc. although Fear and disgust are not antithetical, one may discern similar patterns in other movements.

The third again, I believe has mixed success. It can be ralete to Jams-lange theory of emtoions, where nervous arousal happens first, and emotional feeling or expressions accompanying them follow next.


I am only thus far in my reading of Darwin, but surely will keep doing follow up posts.

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