personality
Major conscious and unconcoscious processes in the brain
May 22nd
Today I plan to touch upon the topic of consciousness (from which many bloggers shy) and more broadly try to delineate what I believe are the important different conscious and unconscious processes in the brain. I will be heavily using my evolutionary stages model for this.
To clarify myself at the very start , I do not believe in a purely reactive nature of organisms; I believe that apart from reacting to stimuli/world; they also act , on their own, and are thus agents. To elaborate, I believe that neuronal groups and circuits may fire on their own and thus lead to behavior/ action. I do not claim that this firing is under voluntary/ volitional control- it may be random- the important point to note is that there is spontaneous motion.
- Sensory system: So to start with I propose that the first function/process the brain needs to develop is to sense its surroundings. This is to avoid predators/ harm in general. this sensory function of brain/sense organs may be unconscious and need not become conscious- as long as an animal can sense danger, even though it may not be aware of the danger, it can take appropriate action – a simple ‘action’ being changing its color to merge with background.
- Motor system:The second function/ process that the brain needs to develop is to have a system that enables motion/movement. This is primarily to explore its environment for food /nutrients. Preys are not going to walk in to your mouth; you have to move around and locate them. Again , this movement need not be volitional/conscious – as long as the animal moves randomly and sporadically to explore new environments, it can ‘see’ new things and eat a few. Again this ‘seeing’ may be as simple as sensing the chemical gradient in a new environmental.
- Learning system: The third function/process that the brain needs to develop is to have a system that enables learning. It is not enough to sense the environmental here-and-now. One needs to learn the contingencies in the world and remember that both in space and time. I am inclined to believe that this is primarily pavlovaion conditioning and associative learning, though I don’t rule out operant learning. Again this learning need not be conscious- one need not explicitly refer to a memory to utilize it- unconscious learning and memory of events can suffice and can drive interactions. I also believe that need for this function is primarily driven by the fact that one interacts with similar environments/con specifics/ predators/ preys and it helps to remember which environmental conditions/operant actions lead to what outcomes. This learning could be as simple as stimuli A predict stimuli B and/or that action C predicts reward D .
- Affective/ Action tendencies system .The fourth function I propose that the brain needs to develop is a system to control its motor system/ behavior by making it more in sync with its internal state. This I propose is done by a group of neurons monitoring the activity of other neurons/visceral organs and thus becoming aware (in a non-conscious sense)of the global state of the organism and of the probability that a particular neuronal group will fire in future and by thus becoming aware of the global state of the organism , by their outputs they may be able to enable one group to fire while inhibiting other groups from firing. To clarify by way of example, some neuronal groups may be responsible for movement. Another neuronal group may be receiving inputs from these as well as say input from gut that says that no movement has happened for a time and that the organism has also not eaten for a time and thus is in a ‘hungry’ state. This may prompt these neurons to fire in such a way that they send excitatory outputs to the movement related neurons and thus biasing them towards firing and thus increasing the probability that a motion will take place and perhaps the organism by indulging in exploratory behavior may be able to satisfy hunger. Of course they will inhibit other neuronal groups from firing and will themselves stop firing when appropriate motion takes place/ a prey is eaten. Again nothing of this has to be conscious- the state of the organism (like hunger) can be discerned unconsciously and the action-tendencies biasing foraging behavior also activated unconsciously- as long as the organism prefers certain behaviors over others depending on its internal state , everything works perfectly. I propose that (unconscious) affective (emotional) state and systems have emerged to fulfill exactly this need of being able to differentially activate different action-tendencies suited to the needs of the organism. I also stick my neck out and claim that the activation of a particular emotion/affective system biases our sensing also. If the organism is hungry, the food tastes (is unconsciously more vivid) better and vice versa. thus affects not only are action-tendencies , but are also, to an extent, sensing-tendencies.
- Decisional/evaluative system: the last function (for now- remember I adhere to eight stage theories- and we have just seen five brain processes in increasing hierarchy) that the brain needs to have is a system to decide / evaluate. Learning lets us predict our world as well as the consequences of our actions. Affective systems provide us some control over our behavior and over our environment- but are automatically activated by the state we are in. Something needs to make these come together such that the competition between actions triggered due to the state we are in (affective action-tendencies) and the actions that may be beneficial given the learning associated with the current stimuli/ state of the world are resolved satisfactorily. One has to balance the action and reaction ratio and the subjective versus objective interpretation/ sensation of environment. The decisional/evaluative system , I propose, does this by associating values with different external event outcomes and different internal state outcomes and by resolving the trade off between the two. This again need not be conscious- given a stimuli predicting a predator in vicinity, and the internal state of the organism as hungry, the organism may have attached more value to ‘avoid being eaten’ than to ‘finding prey’ and thus may not move, but camouflage. On the other hand , if the organisms value system is such that it prefers a hero’s death on battlefield , rather than starvation, it may move (in search of food) – again this could exist in the simplest of unicellular organisms.
Of course all of these brain processes could (and in humans indeed do) have their conscious counterparts like Perception, Volition,episodic Memory, Feelings and Deliberation/thought. That is a different story for a new blog post!
And of course one can also conceive the above in pure reductionist form as a chain below:
sense–>recognize & learn–>evaluate options and decide–>emote and activate action tendencies->execute and move.
and then one can also say that movement leads to new sensation and the above is not a chain , but a part of cycle; all that is valid, but I would sincerely request my readers to consider the possibility of spontaneous and self-driven behavior as separate from reactive motor behavior.
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The first 30 seconds: Trustworthiness, Dominance and their neural correlates
Mar 23rd
A lot has already been written in the blogosphre regarding this study that found the brain regions that are involved in first impression formation. I view the study from a slightly different angle , but first let me introduce the study and its main findings.
The study was focused on finding the brain regions that are involved in the impression formation of a new social entity. We all know that we form automatic and consistent first impressions of strangers we meet based on things like their face to the social information that is available about them. The authors theorized that to know which regions of the brain are involved in evaluating a person for the first time, it would be sufficient to know which regions of the brain were engaged more while the evaluation-consistent information was being processed. To understand this logic, consider the brain regions involved in memory and how they are discovered. Typically, a series of words/images to be remembered are presented to the subjects, while simultaneously their brain are imaged. Later a memory recall/recognition test is administered. It is found that some brain regions are consistently more active during encoding of the original stimuli which are later recalled/ recognized correctly. This effect is know as Difference in Memory effect (DM effect). the fact that these areas are differentially engaged during encoding of remembered stimuli as opposed to forgotten stimuli is taken as evidence for the fact that these brain regions are involved in encoding of memory. Similar to this effect, it is found that evaluations that are consistent with the later overall evaluation of the person engage some brain regions more than when the evaluation is inconsistent with the later overall evaluation. This difference in evaluation effect (DE ) can be used to locate the regions that are involved in social evaluation or formation of first impressions.
Previous studies had indicated that dmPFC was engaged in social evaluation; however many cognitive factors other than purely evaluative factors might be in action here.
It has also been indicated that amygdala is involved in both social evaluation and valence based evaluations and might be involved in these first impression formation. So the authors hypothesized that they would find differential activity in amygdala in consistent as opposed to inconsistent evaluations and this is what they actually observed. They also found that PCC was also differentially engaged while forming first impressions and thus was another brain region involved in evaluating others.
Here is the study design:
To test these hypotheses, we developed the difference in evaluation procedure (see Figure), allowing us to sort social information encoding trials by subsequent evaluations. More specifically, we measured blood oxygenation level–dependent (BOLD) signals using whole brain fMRI during exposure to different person profiles. Each profile consisted of 6 person-descriptive sentences implying different personality traits. The sentences varied gradually in their positive to negative valence (or vice versa) but evoked equivalent levels of arousal. A 12-s interval with the face alone separated the positive and the negative segments. Subsequently, an evaluation slide instructed subjects to form their impression on an 8-point scale. On the basis of these evaluations, we determined which of the presented descriptive sentences guided evaluations (evaluation relevant) and which did not (evaluation irrelevant). For example, if a subject’s evaluation was positive, we assigned the positive segment of the profile to the evaluation-relevant category and the negative segment to the evaluation-irrelevant category. We then identified the brain regions dissociating items from each category (that is, difference in evaluation effect). Notably, we correlated subjects’ BOLD signal with their own individual evaluations. This allowed us to identify brain regions that were consistent across subjects in processing evaluation-relevant information regardless of the particular stimuli that they considered. Immediately after the scanning session, subjects underwent a memory-recognition task.
The results were clear and found that while dmPFC was involved in social evaluations it was not differentially engaged: thus it had a general role to play, perhaps holding the representation of evaluation after it had already been formed; in contrast both amygdala and PCC were differentially recruited and thus underlie the first time evaluations. In the words of the authors:
Understanding the neural substrates of social cognition has been one of the core motivations driving the burgeoning field of social neuroscience. A number of studies have highlighted the dmPFC in the processing of social information. Our results provide further evidence that the dmPFC is recruited to process person-descriptive information during impression formation. However, BOLD responses in this region do not dissociate evaluation-relevant from evaluation-irrelevant information, suggesting that the dmPFC is not essential for the evaluative component of impression formation. In fact, social evaluation recruits brain regions that are not socially specialized but are more generally involved in valuation and emotional processes.
Valuation and emotional processes, as a substantial amount of research has shown, are characteristic of the amygdala. In particular, the amygdala is considered to be a crucial region in learning about motivationally important stimuli. It is also implicated in social inferences that are based on facial and bodily expressions, in inferences of trustworthiness and in the capacity to infer social attributes. Moreover, the involvement of amygdala in social inferences might be independent of awareness or explicit memory. For example, increased amygdala responses were correlated with implicit, but not explicit, measures of the race bias, as well as with presentation of faces previously presented in an emotional, but not neutral, context, regardless of whether subjects could explicitly retrieve this information. Here we provide evidence linking the two domains of affective learning and social processing by showing that the amygdala is engaged in the formation of subjective value assigned to another person in a social encounter.
Although the amygdala is typically implicated in the processing of negative affect and negative stimuli have been shown to modulate it more than positive stimuli, we found that the amygdala processed both positive and negative evaluation-relevant information, suggesting that amygdala activity is driven by factors other than mere valence, such as the motivational importance or salience of the stimuli. This result is consistent with recent findings showing enhanced amygdala responses for both positive and negative stimuli as a function of motivational importance.
Evidence related to the PCC has been more diverse. There have been reports in the social domain, such as involvement in theory of mind and self-referential outward-focused thought33, in memory related processes such as autobiographical memory of family and friends34, and in emotional modulation of memory and attention. More recently, the PCC has been linked with economic decision making, the assignment of subjective value to rewards under risk and uncertainty, and credit assignment in a social exchange. A common denominator of these studies might be that all involved either a social or an outward-directed valuation component. Our task also encompasses these features, extending the role of the PCC to value assignment to social information guiding our first impressions of others.
The amygdala and the PCC are both interconnected with the thalamus as part of a larger circuitry that is implicated in emotion, arousal and learning. Beyond the known role of the amygdala and the PCC in social-information processing and value representation, our results suggest a neural mechanism underlying the online formation of first impressions. When encoding everyday social information during a social encounter, these regions sort information on the basis of its personal and subjective importance and summarize it into an ultimate score, a first impression. Other regions, such as the ventromedial PFC, the striatum and the insula, have also been implicated in valuation processes. However, these regions did not emerge in our difference in evaluation effect analysis. This might suggest a possible dissociation in the valuation network between regions engaged in the formation of value and its subsequent representation and updating. The latter regions would not be engaged during encoding and therefore would not show a difference in evaluation effect but would instead have an effect once the evaluation is formed. The amygdala and the PCC probably participate in both value formation and its representation. The difference in evaluation procedure may provide a useful tool for disentangling the different components of the valuation system and their specific contributions to social versus nonsocial evaluations.
Now I would like to link all this new research with an earlier research on face attributes that found that there were two orthogonal factors that characterize a face- trustworthiness (valence) and dominance. It is important to note that faces are an important mechanism by which we make snap judgments and if it has been found that there are two orthogonal dimensions (found using factor analysis) on which we judge faces and form rifts impressions, there is no reason to suppose that those same two orthogonal factors would not come into play when we form first impressions based on social information and not the face. What I am trying to say is that the non-face social information driven social evaluation would still be structured around the factors of whether the social information pointed to the person as Trustworthy or as Dominant. I would expect that there would be different brain regions specialized for these two functions: We all know too clearly that amygdala is specialized for trustworthiness judgments and that fits in with one of the areas that has been identified for snap judgments. thta leaves us with the PCC, which has normally been implicated in self-referential thinking with an outward and evaluative (as opposed to inward and executive) focus and also a preventive focus. It seems likely that this region would be used to evaluate a social other and judge as to whether he has the ability to execute, harm and dominate oneself. So, what I would like to see is a study that dissociates the scoial information provided to subjects in terms of trustworthiness and dominance factors and sees if there is a dissociation in the evaluative regions of amygdala and PCC; or maybe one can juts factor analyze the results of the original study and see if the same two factors emerge! I am excited,and would love to see these studies being preformed!!
Schiller, D., Freeman, J., Mitchell, J., Uleman, J., & Phelps, E. (2009). A neural mechanism of first impressions Nature Neuroscience DOI: 10.1038/nn.2278
Oosterhof, N., & Todorov, A. (2008). The functional basis of face evaluation Proceedings of the National Academy of Sciences, 105 (32), 11087-11092 DOI: 10.1073/pnas.0805664105
Cultural differences are Vodoo correlations: I beg to differ
Mar 6th
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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An online personality guessing experiment
Feb 25th
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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Perosnality and Neurotransmitters
Jan 22nd
Although all introductory Psychology textbooks warn against any simplistic correlations between neurotransmitters and complex behavioral and cognitive measures like Personality traits, I am going to do exactly that in this post. In an earlier post , I had related personality traits to neurotransmitter systems and operant learning paradigm and here I present some corroborating evidence for the personality- neurotransmitter system linkage.
First to recap:
- Nueroticism/ Harm Avoidance: Serotonin system
- Conscentiousness/ novelty seeking: Dopamine system
- Extarversion/ Reward Dependence: Norepinephrine system
- Agreeableness/ Persistance: Epinepherine system
- Openesses/ Rebeliious-conformity/self-directedness: Histamine system
First off to bat consider the following- Neuroticism is manifested as anxiety and if serotonin system is implicated , then genes affecting the serotonin system should affect the neuroticism levels of individuals . This is exactly what was found by Lesh et al.
Transporter-facilitated uptake of serotonin (5-hydroxytryptamine or 5-HT) has been implicated in anxiety in humans and animal models and is the site of action of widely used uptake-inhibiting antidepressant and antianxiety drugs. Human 5-HT transporter (5-HTT) gene transcription is modulated by a common polymorphism in its upstream regulatory region. The short variant of the polymorphism reduces the transcriptional efficiency of the 5-HTT gene promoter, resulting in decreased 5-HTT expression and 5-HT uptake in lymphoblasts. Association studies in two independent samples totaling 505 individuals revealed that the 5-HTT polymorphism accounts for 3 to 4 percent of total variation and 7 to 9 percent of inherited variance in anxiety-related personality traits in individuals as well as sibships.
Next comes a recent study finding that a gene variant related to NO (a neurotrasmitter) is related to Impulsiveness. Now One of the defining traits of NS/ C is Impulsiveness. This has been found related to NOS1 gene. Here is the original study.
Context Human personality is characterized by substantial heritability but few functional gene variants have been identified. Although rodent data suggest that the neuronal isoform of nitric oxide synthase (NOS-I) modifies diverse behaviors including aggression, this has not been translated to human studies.
Objectives To investigate the functionality of an NOS1 promoter repeat length variation (NOS1 Ex1f variable number tandem repeat [VNTR]) and to test whether it is associated with phenotypes relevant to impulsivity.
Design Molecular biological studies assessed the cellular consequences of NOS1 Ex1f VNTR; association studies were conducted to investigate the impact of this genetic variant on impulsivity; imaging genetics was applied to determine whether the polymorphism is functional on a neurobiological level.
Setting Three psychiatric university clinics in Germany.
Participants More than 3200 subjects were included in the association study: 1954 controls, 403 patients with personality disorder, 383 patients with adult attention-deficit/hyperactivity disorder (ADHD), 151 with familial ADHD, 189 suicide attempters, and 182 criminal offenders.
Main Outcome Measures For the association studies, the major outcome criteria were phenotypes relevant to impulsivity, namely, the dimensional phenotype conscientiousness and the categorical phenotypes adult ADHD, aggression, and cluster B personality disorder.
Results A novel functional promoter polymorphism in NOS1 was associated with traits related to impulsivity, including hyperactive and aggressive behaviors. Specifically, the short repeat variant was more frequent in adult ADHD, cluster B personality disorder, and autoaggressive and heteroaggressive behavior. This short variant came along with decreased transcriptional activity of the NOS1 exon 1f promoter and alterations in the neuronal transcriptome including RGS4 and GRIN1. On a systems level, it was associated with hypoactivation of the anterior cingulate cortex, which is involved in the processing of emotion and reward in behavioral control.
Conclusion These findings implicate deficits in neuronal signaling via nitric oxide in moderation of prefrontal circuits underlying impulsivity-related behavior in humans.
Now there does exist a relationship between NO and dopamine (but then which two neurotransmitter systems are not related) and that way I can still save my face by claiming that it is the dopamine that is finally mediating the impulsivity and not NO.
There is evidence suggesting that nitric oxide (NO) may play an important role in dopamine (DA) cell death. NO may act as a neuroprotector or neurotoxic agent in dopamine neurons, depending on cell redox status. Glutathione (GSH) depletion is the earliest biochemical alteration shown to date in brains of Parkinson’s disease (PD) patients. However, data from animal models show that GSH depletion by itself is not sufficient to induce nigral degeneration. Low NO concentrations have neurotrophic effects on DA cells via a cGMP-independent mechanism that may implicate up-regulation of GSH. On the other hand, higher levels of NO induce cell death in both DA neurons and mature oligodendrocytes that is totally reverted by soluble factors released from glia. Alterations in GSH levels change the neurotrophic effects of NO in dopamine function into neurotoxic, under these conditions, NO triggers a programmed cell death with markers of both apoptosis and necrosis characterised by an early production of free radicals followed by late activation of the sGC/cGMP/PKG pathway. Arachidonic acid metabolism through the 12-lipoxygenase (12-LOX) pathway is also central for this GSH-NO interaction. Neurotrophism of NO switches into neurotoxicity after GSH depletion, due to persistent activation of the ERK-1/2 signaling pathway in glial cells. The implication of these cell death signaling pathways in pathological conditions like Parkinson’s disease, where GSH depletion, glial dysfunction and NO overproduction have been documented, are discussed.
Next we move to the sociability factor underlying Extraversion/ Reward dependence. Here studies show that Noardrenaline is related to sociability/ dependence etc. Here is a study showing effects of NA on sociability.
Rationale: Treatment with antidepressants has been shown to affect social functioning, but drugs with actions on different neurotransmitters may have a different profile of effects. Objective: To study the effects of acute manipulation of two neurotransmitters, serotonin and noradrenaline, on social behaviour in healthy volunteers. Methods: Sixty volunteers were randomly assigned to a single dose of a selective noradrenaline reuptake inhibitor, reboxetine (4 mg), a selective serotonin reuptake inhibitor, citalopram (10 mg), or placebo. They socially interacted with a confederate behaving in a non-sociable manner in a stranger-dyadic social interaction paradigm 1.5 h postdrug. Social behaviour during the interaction was video recorded by a hidden camera and subsequently analysed. After the interaction, volunteers played the mixed-motive game with the confederate. This game has been shown to measure cooperative behaviour and communication. Volunteers read a short story and rated their mood predrug and before and after the interaction. Results: Subjects on reboxetine showed reduced hand fiddling during the interaction and gave significantly more cooperative communications during the mixed-motive game. More volunteers on reboxetine were classified as cooperative players. On the reading task, the speech of subjects on citalopram showed less reduction of energy variation after the social interaction. Conclusion: Reboxetine had clear effects on social behaviour. Noradrenaline was related to increased social engagement and cooperation and a reduction in self-focus. Citalopram had less effect on cooperative behaviour but serotonin may be associated with protection of the self from the negative consequences of social interaction.
Also, Zuckerman has clearly related NA to sociability and dependence.As per him:
Ellison studies the effects of chemical lesions of either dopamine or noradrenaline system in rats. …Norepeinepherine-lesioned rats spent more time in their burrows and less time in a behavioral arena in which spontaneous social interactions could occur….
That takes us to the fourth trait of agreeableness and the related Empathy system . Here the famous Scacter- singer experiment of administering Adrenaline and then finding that the mood became congruent with that of other people has to be reinterpreted in terms of empathy at work rather than james-lange two-step appraisal of emotion. Do read the expermine in more detail at the above link.
The Experiment in a nut shell.
Independent Variables1. Injected Adrenaline or Saline solution
2. The subjects were given a description of side-effects, misinformed about the side-effects, or told nothing.
3. The subjects were placed in a ‘Euphoric’ (Happy) or ‘Angry’ situation.Dependent Variables
1. Observed signs of happiness
2. Observed signs of anger
3. Self-report of happiness or anger
Results:
Euphoria: As expected, the adrenaline misinformed group, and the adrenaline ignorant group, reported being happiest
Anger: This didn’t work. Most subjects were positive about their feelings. Schachter and Singer attribute this to the fact that they were students eager to please their tutors
It is important that those people who were placed with confederates exhibiting happy states felt happy and the same was felt by those who received adrenaline; a more valid interpretation is that adrenaline increased the empathetic feelings and lead to transmission or contagion of mood. the situational variable where one tried to induce anger by being irritable did not lead to to anger; perhaps if the confederate was irritated, they might have become irritated too due to empathy; but no anger is expected as per my interpretation that it is empathy that is primary and not the cognitive appraisal of emotional physiological state.
Finally I agree that I have not been able to find much about histamine system and how it may be affect the openness/ rebellious/conformity trait. As an exercise to reader here are some low histamine condition links.
That is it for now. would love if somebody points to some other studies that corroborate the case.
K.-P. Lesch, D. Bengel, A. Heils, S. Z. Sabol, B. D. Greenberg, S. Petri, J. Benjamin, C. R. Muller, D. H. Hamer, D. L. Murphy (1996). Association of Anxiety-Related Traits with a Polymorphism in the Serotonin Transporter Gene Regulatory Region Science, 274 (5292), 1527-1531 DOI: 10.1126/science.274.5292.1527
Wai Tse, Alyson Bond (2002). Difference in serotonergic and noradrenergic regulation of human social behaviours Psychopharmacology, 159 (2), 216-221 DOI: 10.1007/s00213-001-0926-9
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