Archive for December, 2007
Neural correlates of trust
Dec 13th
This is the title of a new paper in PNAS by Krueger et al, that tries to find the neural correlates of conditional and unconditional trust using the sequential, reciprocal trust game. The authors premise is that conditional trust is more costly strategy compared to unconditional trust and might utilize different brain areas as well.
Conditional trust assumes that one’s partner is self-interested and estimates the expected value of one’s strategy with respect to the benefits of cooperating, the risk of defection, and the future value of past decisions; it causes less balanced goodwill and results in greater variance in cooperative decisions and, therefore, is cognitively more costly to maintain. In contrast, unconditional trust assumes that one’s partner is trustworthy and updates the value of one’s partner with respect to their characteristics and past performance; balanced goodwill occurs more quickly, allowing the partners to attain high levels of synchronicity in their decisions and, therefore, is cognitively less costly to maintain. In this work, an examination of functional brain activity supports the hypothesis that the preferential activation of different neuronal systems implements these two trust strategies.
The results of their experiments supported their initial hypothesis and they found that while Para Cingulate cortex (PcC) activation was necessary for menatlizing and initial building of trust; later unconditional and conditional trust strategies deployed different brain areas viz Septal Area (SA) and Ventral Tegmental Area (VTA) respectively.
Unconditional trust assumes that one’s partner is trustworthy. During the building stage, first movers in the nondefector group showed higher activation in the PcC compared with first movers in the defector group. Through mentalizing, partners of this group verified their prior trustworthy assumption, updated the value of one’s partner’s strategy with respect to their past performance, and maintained a balanced goodwill toward each other, allowing them to avoid defections. By developing “better” mental models in this early stage, partners in the nondefector group accumulated sufficient mutual goodwill to become socially attached to each other and adopted an unconditional trust strategy.
During the maintenance stage, the nondefector group showed a higher activation in the SA compared with the defector group. Across groups, pairs who showed the highest trust-reciprocate history in their decisions also showed the highest activation in this region. Furthermore, analyses of pre- and postscan behavioral ratings confirmed that only nondefector pairs felt significantly closer to each other and ranked themselves as being more of a partner to the other person after the experiment. Through early mentalizing, partners in the nondefector group must have balanced goodwill more quickly, allowing them to become synchronized in their decision patterns. Brain-to-brain correlations only increased in the SA region for the nondefector group across stages, and only partners in the nondefector group became synchronized in their SA BOLD amplitudes as first movers in adjacent trials of trust games. Synchronization in the SA led to social attachment associated with a significant decrease in activation in the PcC during the maintenance stage. By adopting this cognitively less costly strategy, decision times became significantly faster for the nondefector group across stages of the experiment.
Conditional trust assumes that one’s partner is self-interested. During the building stage, first movers in the defector group showed less activation in the PcC compared with the nondefector group. Through less mentalizing in the building stage, partners in this group produced higher errors in the inferences of second movers’ goodwill toward them, resulting in less balanced goodwill and, therefore, in less overall trust compared with the nondefector group. More importantly, they started to trust more in the low-payoff games and less in the high-payoff games. This decision pattern implies that defectors were adapting a conditional trust strategy by evaluating the expected value of one’s strategy with respect to the risks and benefits of cooperation.
During the maintenance stage, the defector group showed higher activations in the VTA compared with the nondefector group, a region linked to the dopaminergic mesolimbic reward system providing a general reinforcement mechanism to encode expected and realized reward . Across groups, pairs who shared the lowest trust-reciprocate history in their decisions also showed the highest activation in this region. By adopting a cognitively more costly strategy, partners in the defector group showed a significant increase in activation in the PcC over the experiment. Through more mentalizing in this late stage, first movers in the defector group tried to develop more accurate models about the likelihood of their partner’s choices so that they could make a more advantageous decision about when to trust. The conditional trust strategy paid off less over time as total earnings decreased for the defector group (but increased for the nondefector group) across stages.
Thus, it seems that SA, based on oxytocin and vasopressin and social bonding is a more cost-effective strategy than the VTA based on dompainerigic system based on reward monitoring.
cortex maturation: found the references
Dec 12th
In my earlier post on cortex maturation, I was unable to find the references for the claims that in Autism cortex matures earlier during toddler phase and that even in adulthood, it may be thicker.
In a recent PNAS commentary, reagarding the delay rather than deviance theory of ADHD, I came across the appropriate references to back the above observations, as well as the accelerated pruning in child-onset schizophrenia. Passing that along.
An important question is whether the delay of brain maturation is a specific characteristic of ADHD or is shared by other child psychiatric disorders. So far, none of the other major psychiatric disorders have been associated with a maturational delay of brain structure. However, to my knowledge, longitudinal structural studies have been conducted only in patients with ADHD, childhood-onset schizophrenia (COS), and autism, finding maturational deviance rather than delay. Adolescents with COS are characterized by a striking nonlinear, progressive acceleration of the normal gray matter and volume decrease in cortical regions that levels off in adulthood (22). In autism, there is an early left hemispheric overgrowth of gray and white matter at young toddler age with conflicting findings of either arrested growth or remaining brain enlargement in adolescence and adulthood (23). The findings of delayed structural brain maturation seem, thus far, to be specific to ADHD and may be an important neuroanatomic trait. However, further exploration of the developmental trajectories in other child psychiatric disorders is needed to establish the importance of a delay of brain maturation as a specific neuroanatomic marker for ADHD.
(emphasis mine, references below)
22. Greenstein D, Lerch J, Shaw P, Clasen L, Giedd J, Gochman P, Rapoport J, Gogtay N (2006) J Child Psychol Psychiatry 47:1003–1012.
23. Bashat DB, Kronfeld-Duenias V, Zachor DA, Ekstein PM, Hendler T, Tarrasch R, Even A, Levy Y, Sira LB (2007) NeuroImage 37:40–47.
IQ matters…or does it?
Dec 11th
This is just an FYI post regarding two great articles on IQ.
The first addressees the white-black IQ gap and shows that the gap is due to environmental factors and not genetic. This is a well written article by Malcom Gladwell and is strongly recommended to be read in its entirety. The arguments are manifold:
- Flynn effects show that IQ scores have increased over time, and hence IQ is malleable and prone to environmental influences.
- Intelligence is also a cultural construct and what may be intelligent behavior in one culture may be deemed stupid in another.
- Intelligence can be raised by providing the right socio-cultural environment and cognitive grooming and scaffolding. High heritability may partially be due to the fact that high SES groups are considered in such studies. In poor families IQ heritability drops to 10 to 20 % and environmental factors play a much higher role.
- IQ tests are renormed (to take care of the Flynn effect and the definition of IQ as relative to mean IQ of population) and sometimes data that supports claims like Asians have higher IQ than white which have higher than blacks are comparing apples to oranges.
- IQ gap is narrowing and the average scores of blacks increasing at a faster rate than whites, which is further proof that there is not a racial gap that is due to genetics.
The second article is by Flynn himself and covers some of the same ground. The main essay is followed by several commentaries and it makes for a stimulating exchange.
Perfectionism: devleopmental influences?
Dec 7th
A recent Mind Hacks post, and a comment by John Bunch there, set me thinking, regarding whether perfectionism could have a developmental genesis. Perfectionism , like other personality traits, would likely be having both genetic and environmental factors contributing ti its development. So, before proceeding further, I would like to list the factors of perfectionism as identified in a recent study by Frost et al, they are:
- Excessive concern over making mistakes
- The doubting of quality of one’s actions
- High personal standards
- Perception of high parental expectations and criticisms
- A preference for order and organization
To me they present in a nice order on the five developmental factors related to trust (whether mistakes will be tolerated or not), Autonomy vs shame and doubt(doubting quality of one’s actions), Initiative vs guilt (setting high standards to avoid guilt), industry vs inferiority(judging oneself by perceived parental standards) and finally Identity vs role confusion (having order and organization in life to relive the role confusion). Thus, all the perfectionist traits are a result of some deficient achieving of a developmental milestone – especially in relation to goal pursuing.
Here I come to my second theme- the comment by John Bunch, tries to draw fascinating parallels between the need to avoid mistakes in Perfectionists and the avoidance of risks in Passive Aggressives – and relates both of them to Carol Dwecks work with parsing and installing in children a fixed, entity like belief of personality and intelligence versus a growth mindset that has room for improvements and change. It is worthwhile here to recount Carol Dwecks experiments in which her team found that those children who had fixed, entity like view of intelligence gave up earlier on solving difficult tasks , avoided hard tests, weer more concerned with their image and projecting a good face than in learning – and one can easily see that these are seed for the later perfectionist traits of fear of mistakes, perceived high expectations and criticisms of parents etc. Similarly in Passive Aggressives this translates into risk avoidance – different mechanism chosen, due to underlying genetic temperaments, but to the same environmental stimuli of the fixed intelligence or talent myth installation.
By the way, the five factors of Perfectionsim can also be construed in terms of the big five factors -
- Neuroticism (cognitive)- worry over mistakes.
- Conscientiousness (motivational)- high and unrealistic standards
- Extraversion (behavioural) – doubt over actions
- Agreeableness (social)- perceived criticism and expectations
- Openness (exploratory) – organization and order
I would love to hear more comments on this developmental theory of perfectionism. A quick search on Google revealed a promising dissertation that links perfectionism to helpless explanatory style which fits with Dwecks theory.
Rasing Successful kids
Dec 4th
Carol Dweck, whose research I have covered extensively earlier, writes in this month’s Scientific American Mind , regarding how to raise a successful child. She touches upon the entity vs incremental theories of intelligence, which she frames as fixed and innate abilities vis-a-vis a growth mindset. As per this theory having successful and intelligent children depends on not praising the children for their smarts or intelligence or talent , but on their efforts and hard work. Also, to inculcate in them a sense of brain’s malleability and to view challenges as resulting in growth as a result of facing difficulties and seeing the challenges as opportunities for brain development and learning. this view purportedly leads to more motivation and effort while facing life challenges or solving educational problems. Ironically, the article is titled The Secret to Raising Smart Kids, while in my opinion , to not reinforce the ‘smart’ stereotype, it should have been labeled The Secret to Raising Successful Kids. this would have also captured the recent Strenberg’s emphasis on successful intelligence.
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