Unconscious actions of testosterone

Here is an interesting observation from Terburg et al.:

Throughout vertebrate phylogeny, testosterone has motivated animals to obtain and maintain social dominance—a fact suggesting that unconscious primordial brain mechanisms are involved in social dominance. In humans, however, the prevailing view is that the neocortex is in control of primordial drives, and testosterone is thought to promote social dominance via conscious feelings of superiority, indefatigability, strength, and anger. Here we show that testosterone administration in humans prolongs dominant staring into the eyes of threatening faces that are viewed outside of awareness, without affecting consciously experienced feelings. These findings reveal that testosterone motivates social dominance in humans in much the same ways that it does in other vertebrates: involuntarily, automatically, and unconsciously.

Quantitative analysis of language evolution.

Modern computation techniques and the mass digitization of books have made possible the systematic analysis of one of humankind's most important cultural artifacts, its languages. A analysis by Hughes et al. is quite different from studies in the dating of literary works, the analysis of the coarse-grained structure of literary history (and the evolution of genre), and most notably, a recent analysis of Google Books that examined temporal trends in content-word usage. (One of the co-authors of the study is a polymath, David Krakauer, who recently become Director of our Wisconsin Institute of Discovery here at the University of Wisconsin and is also Co-Director of its Center for Complexity and Collective Computation). Hughes et al. focus on the usage of content-free words as the basis of a first large-scale study of the similarity structure of literary style. Content-free words are the “syntactic glue” of a language: They are words that carry little meaning on their own but form the bridge between words that convey meaning. Their joint frequency of usage is known to provide a useful stylistic fingerprint for authorship, and thus suggests a method of comparing author styles. Their dataset was a subset of 537 authors in the Project Gutenberg database composed of those who wrote after the year 1550, had at least five works in English in the Project Gutenberg collection, and for whom birth and death date information was available. The primary results of the analysis are that time provides the most coherent means of clustering work and that a trend of diminishing stylistic influence is observed as one moves forward in time. Such a finding is consistent with a simple evolutionary model for stylistic influence, which assumes that imitation attends preferentially to contemporary authors. The authors uncover quantitative support of the previously purely anecdotal notion of a literary “style of a time.” They note that their findings suggest the utility and perhaps the creation of a new field of stylometric analysis in culturomics. Here is their abstract:

Literature is a form of expression whose temporal structure, both in content and style, provides a historical record of the evolution of culture. In this work we take on a quantitative analysis of literary style and conduct the first large-scale temporal stylometric study of literature by using the vast holdings in the Project Gutenberg Digital Library corpus. We find temporal stylistic localization among authors through the analysis of the similarity structure in feature vectors derived from content-free word usage, nonhomogeneous decay rates of stylistic influence, and an accelerating rate of decay of influence among modern authors. Within a given time period we also find evidence for stylistic coherence with a given literary topic, such that writers in different fields adopt different literary styles. This study gives quantitative support to the notion of a literary “style of a time” with a strong trend toward increasingly contemporaneous stylistic influence.

It seems a bit amazing that their analysis of the use of 307 content-free words that included prepositions, articles, conjunctions, “to be” verbs, and some common nouns and pronouns allowed them to cluster authors in time and by narrative theme, and that content-free word frequencies were found to be fairly faithfully transmitted among authors of a similar period, even when imitation at this level of textual resolution seems to be out of the question. Moving into the present, this imitation becomes increasingly localized to our contemporaries. Further edited clips:

We propose that for the earliest periods in our dataset, and through the early modern period, the number of published works remained relatively low. This allowed authors to have sufficient time to sample (read) very broadly from the full range of historically published works. Common phrasing, and norms of syntax and grammar, remain relatively unchanged for long periods of time. This generates decay rates in similarity as a function of temporal distance that are not significantly different from the average, because authors are influenced by models distributed uniformly in time. However, for more recent authors, the number of possible choices of books to read has increased dramatically, and with a finite amount of time, a subset of these works must be chosen, leading to rather heterogeneous reading patterns and a greater overall diversity of authored works. The pattern accelerates in the later modern period, with even more authors to choose from and selection dominated by contemporaneous authors. This suggests a simple evolutionary model for patterns of influence.

The negative influence of authors from a preceding generation in the period 1907–1952 could be explained by the Modernist movement. Modernist authors, who are contained within this time period, display a radical shift in style as they reject their immediate stylistic predecessors yet remain a part of a dominant movement that included many of their contemporaries. The contemporary influence of writing programs and their often close readings of contemporary works and feedback (sometimes called “reflexive modernism”) has also been suggested to contribute to this effect. The overall pattern that we find is that the stylistic influence of the past is diminishing at an increasing rate, which suggests that style itself is evolving at an accelerating pace.

The patterns of influence are a first discovery from the corpus. Implicit in this is a temporal clustering of similarity and quantitative support for the qualitative suggestions of a notion of a “style of a time.” It is also worth noting that the implicit temporal clustering of similarity is not an exclusively temporal phenomenon. A network representation of the authors reveals evidence of thematic clustering as well. Examples include interesting groupings of English poets and playwrights, military leaders, and a collection of important naturalists, social thinkers, and historians. This is suggestive and supportive of the hypothesis that word frequencies are not only typical of a given time but also of a field of inquiry. Historians and naturalists do not only write about different topics, they write about them differently. Taken together with the patterns of decay in influence this suggests that whereas authors of the 18th and 19th centuries continued to be influenced by previous centuries, authors of the late 20th century are strongly influenced by authors from their own decade. The so-called “anxiety of influence”, whereby authors are understood in terms of their response to canonical precursors, is becoming an “anxiety of impotence,” in which the past exerts a diminishing stylistic influence on the present. These results are consistent with many complex, scaling phenomena such as those found in urban and technological systems, where there has been an accelerating rate of change into the present. This is a rather intriguing pattern of short-term cultural evolution that is different from the constant rates of change reported for names and pottery or the reduced rates of lexical substitution of frequently used words over thousands of years. Further analysis will elucidate not only the transmission mechanisms generating temporally localized styles but additional stylistic factors that help differentiate the style of one author from that of another.

Social jetlag and obesity.

Roenneberg et al. do an epidemiological study, showing that, beyond sleep duration, the difference between natural circadian sleep rhythm and the actual times of sleep people observe (social jetlag) is associated with increased body mass index. They suggest that living “against the clock” may be a factor contributing to the modern epidemic of obesity. (But... it seems to me people were doing this before the obesity epidemic was noted. Most experts attribute the epidemic to increased physical inactivity and abundance of cheap highly caloric foods.) Here is their summary and abstract:

-In 70% of the population, biological and social clocks differ by >1 hr (social jetlag) -Social jetlag is a predictor of BMI, especially for overweight individuals -The decrease of sleep duration over the past decade concerns only workdays -Individuals are progressively exposed to decreasing light, and their chronotypes delay

Abstract

Obesity has reached crisis proportions in industrialized societies. Many factors converge to yield increased body mass index (BMI). Among these is sleep duration. The circadian clock controls sleep timing through the process of entrainment. Chronotype describes individual differences in sleep timing, and it is determined by genetic background, age, sex, and environment (e.g., light exposure). Social jetlag quantifies the discrepancy that often arises between circadian and social clocks, which results in chronic sleep loss. The circadian clock also regulates energy homeostasis, and its disruption—as with social jetlag—may contribute to weight-related pathologies. Here, we report the results from a large-scale epidemiological study, showing that, beyond sleep duration, social jetlag is associated with increased BMI. Our results demonstrate that living “against the clock” may be a factor contributing to the epidemic of obesity. This is of key importance in pending discussions on the implementation of Daylight Saving Time and on work or school times, which all contribute to the amount of social jetlag accrued by an individual. Our data suggest that improving the correspondence between biological and social clocks will contribute to the management of obesity.

Social interactions prime us for motor empathy or resonance.

Hogeveen and Obhi1 find that recent experience tunes our mirroring systems to particular agent types. A bit from their introduction, followed by the abstract:

Detecting and responding to biological stimuli such as predators or potential mates is a fundamental and adaptive capability, supported by rain areas such as the posterior superior temporal sulcus (pSTS) which is biased for processing biological motion. The pSTS and the parietofrontal mirror system form part of a wider action observation network (AON), which is thought to underlie many social abilities. Motor resonance (MR) is the activation of matching motor representations during observation of action(s) made by others, and could index mirror activity within the wider AON.

Understanding the neural basis of social behavior has become an important goal for cognitive neuroscience and a key aim is to link neural processes observed in the laboratory to more naturalistic social behaviors in real-world contexts. Although it is accepted that mirror mechanisms contribute to the occurrence of motor resonance (MR) and are common to action execution, observation, and imitation, questions remain about mirror (and MR) involvement in real social behavior and in processing nonhuman actions. To determine whether social interaction primes the MR system, groups of participants engaged or did not engage in a social interaction before observing human or robotic actions. During observation, MR was assessed via motor-evoked potentials elicited with transcranial magnetic stimulation. Compared with participants who did not engage in a prior social interaction, participants who engaged in the social interaction showed a significant increase in MR for human actions. In contrast, social interaction did not increase MR for robot actions. Thus, naturalistic social interaction and laboratory action observation tasks appear to involve common MR mechanisms, and recent experience tunes the system to particular agent types.

Serotonin modulates reward value in our decision making.

Seymour et al. find further behavioral and neural evidence that serotonin modulates (is necessary for) distinct behavioral and anatomical components of decision-making. Most surprising is their observation of a strongly positive dependence of reward outcome value on serotonin signaling, with corresponding cue-value-related activity in vmPFC and prediction-error-related activity in dorsolateral putamen (for errors). This value-dependent effect was behaviorally and anatomically distinct from an effect of serotonin on behavioral flexibility, as indicated by choice perseveration. Here is their abstract:

Establishing a function for the neuromodulator serotonin in human decision-making has proved remarkably difficult because if its complex role in reward and punishment processing. In a novel choice task where actions led concurrently and independently to the stochastic delivery of both money and pain, we studied the impact of decreased brain serotonin induced by acute dietary tryptophan depletion. Depletion selectively impaired both behavioral and neural representations of reward outcome value, and hence the effective exchange rate by which rewards and punishments were compared. This effect was computationally and anatomically distinct from a separate effect on increasing outcome-independent choice perseveration. Our results provide evidence for a surprising role for serotonin in reward processing, while illustrating its complex and multifarious effects.

The neurogenetics of nice.

Interesting observations from Poulin et al...They note that all prosocial acts require people to contend with concerns about potential exploitation or loss of resources (i.e., threats). If oxytocin and vasopressin moderate responses to such threats, they may influence a wide variety of prosocial behaviors, including those outside a laboratory context. It is known that oxytocin administration reduces amygdalar reactivity to negative stimuli,and amygdalar reactivity, in turn, mediates oxytocin’s effects on generosity in the context of an economic game. The G/G genotype of the rs53576 single-nucleotide polymorphism (SNP) for OXTR also predicts lower cardiovascular reactivity to startle anticipation than do the A/A and A/G genotypes. Here is their abstract:

Oxytocin, vasopressin, and their receptor genes influence prosocial behavior in the laboratory and in the context of close relationships. These peptides may also promote social engagement following threat. However, the scope of their prosocial effects is unknown. We examined oxytocin receptor (OXTR) polymorphism rs53576, as well as vasopressin receptor 1a (AVPR1a) polymorphisms rs1 and rs3 in a national sample of U.S. residents (n = 348). These polymorphisms interacted with perceived threat to predict engagement in volunteer work or charitable activities and commitment to civic duty. Specifically, greater perceived threat predicted engagement in fewer charitable activities for individuals with A/A and A/G genotypes of OXTR rs53576, but not for G/G individuals. Similarly, greater perceived threat predicted lower commitment to civic duty for individuals with one or two short alleles for AVPR1a rs1, but not for individuals with only long alleles. Oxytocin, vasopressin, and their receptor genes may significantly influence prosocial behavior and may lie at the core of the caregiving behavioral system.

Higher maternal cortisol correlates with later affective problems.

Sobering data from Buss et al:

Stress-related variation in the intrauterine milieu may impact brain development and emergent function, with long-term implications in terms of susceptibility for affective disorders. Studies in animals suggest limbic regions in the developing brain are particularly sensitive to exposure to the stress hormone cortisol. However, the nature, magnitude, and time course of these effects have not yet been adequately characterized in humans. A prospective, longitudinal study was conducted in 65 normal, healthy mother–child dyads to examine the association of maternal cortisol in early, mid-, and late gestation with subsequent measures at approximately 7 y age of child amygdala and hippocampus volume and affective problems. After accounting for the effects of potential confounding pre- and postnatal factors, higher maternal cortisol levels in earlier but not later gestation was associated with a larger right amygdala volume in girls (a 1 SD increase in cortisol was associated with a 6.4% increase in right amygdala volume), but not in boys. Moreover, higher maternal cortisol levels in early gestation was associated with more affective problems in girls, and this association was mediated, in part, by amygdala volume. No association between maternal cortisol in pregnancy and child hippocampus volume was observed in either sex. The current findings represent, to the best of our knowledge, the first report linking maternal stress hormone levels in human pregnancy with subsequent child amygdala volume and affect. The results underscore the importance of the intrauterine environment and suggest the origins of neuropsychiatric disorders may have their foundations early in life.

Seeing where our brains think about our thinking

More fascinating work from Ray Dolan's group at the Wellcome Trust Center for Neuroimaging at University College, London:

Neuroscience has made considerable progress in understanding the neural substrates supporting cognitive performance in a number of domains, including memory, perception, and decision making. In contrast, how the human brain generates metacognitive awareness of task performance remains unclear. Here, we address this question by asking participants to perform perceptual decisions while providing concurrent metacognitive reports during fMRI scanning. We show that activity in right rostrolateral prefrontal cortex (rlPFC) satisfies three constraints for a role in metacognitive aspects of decision-making. Right rlPFC showed greater activity during self-report compared to a matched control condition, activity in this region correlated with reported confidence, and the strength of the relationship between activity and confidence predicted metacognitive ability across individuals. In addition, functional connectivity between right rlPFC and both contralateral PFC and visual cortex increased during metacognitive reports. We discuss these findings in a theoretical framework where rlPFC re-represents object-level decision uncertainty to facilitate metacognitive report.

I'll also pass on Figure 5 and it's legend from the text:

Individual difference and connectivity analyses. The top panel illustrates the significant correlation between confidence-related activity in right rlPFC and metacognitive accuracy across subjects. The bottom panel depicts results of an exploratory psychophysiological interaction analysis (displayed at p < 0.001, uncorrected), revealing whole-brain corrected (p < 0.05) increases in connectivity between right rlPFC and visual cortex (lingual gyrus) and between right rlPFC and left dlPFC in Report compared to Follow trials.

My amygdala made me do it...

James Atlas writes an engaging piece on a topic that has been the subject of many MindBlog posts: how our supposedly rational 'upstairs' decisions are actually nudged or determined by unconscious or implicit 'downstairs' mechanisms. He doesn't include in his list of recent books Jonathan Haidt's "The Righteous Mind", which is beautifully written and one of those few books I actually read through, rather than just reading its reviews. A few clips from the Atlas article:

WHY are we thinking so much about thinking these days?...Jonah Lehrer’s “Imagine: How Creativity Works,” ...Charles Duhigg’s book “The Power of Habit: Why We Do What We Do in Life and Business,” ...“Subliminal: How Your Unconscious Mind Rules Your Behavior,” by Leonard Mlodinow...Kahneman's “Thinking, Fast and Slow” goes to the heart of the matter: How aware are we of the invisible forces of brain chemistry, social cues and temperament that determine how we think and act? Has the concept of free will gone out the window?

These books possess a unifying theme: The choices we make in day-to-day life are prompted by impulses lodged deep within the nervous system. Not only are we not masters of our fate; we are captives of biological determinism. Once we enter the portals of the strange neuronal world known as the brain, we discover that — to put the matter plainly — we have no idea what we’re doing.

The 18th-century philosopher David Hume (much quoted by Mr. Lehrer) didn’t have an M.R.I. scanner at his disposal, but he framed the question in much the same way. His major work, “A Treatise of Human Nature,” explored the ways in which habit, or “custom,” rules our lives. Hume’s experiments with perception — how we respond to colors, distance, numerical sets — prefigure the rigorous science of Professor Kahneman. His intent was to show us “the natural infirmity and unsteadiness both of our imagination and senses.” Consciousness, like philosophy itself, stands on a “weak foundation.”

If Hume seems modern, William James reads like a contemporary. Writing toward the end of the 19th century, James addressed the same question that had concerned Hume — how the unconscious operates as a physical process, not just, as Freud would have it, a mental one. In his now-classic essay, “Habit,” he argued that even our most complex acts are reflexive — “concatenated discharges in the nerve-centres.” ...we can train ourselves to change if we work at it hard enough. Self-awareness sets us free. “The great thing, then, in all education,” writes James, “is to make our nervous system our ally instead of our enemy.”

Does this mean we have no “agency,” no capacity to act on our own? Or can autonomy thrive within the prison of self-ignorance? “We have to believe it does,” says Steven Lukes, a professor of sociology at New York University highly admired for his work in moral philosophy. “If we seriously thought that our intentions made no difference to how we behave, we couldn’t go on using the language of ethics. How would we go on living the lives we live?” Or doing what we think is right? “People have free will when they ‘feel’ they have free will,” says Professor Kahneman. “If we didn’t believe in it, we would have no responsibility.”

But of course what one “feels,” as we’ve learned from all these books, could well be — indeed, probably is — an illusion. As Timothy Wilson puts it with haunting simplicity: “We are strangers to ourselves.” Hopefully...Strangers who can learn how to be friends.

The sentiments above are very much in the vein of my "I-Illusion" web lecture.

Further cognitive advantages of bilinguals.

Interesting work from Krizman et al.:

Bilingualism profoundly affects the brain, yielding functional and structural changes in cortical regions dedicated to language processing and executive function [Crinion J, et al. (2006) Science 312:1537–1540; Kim KHS, et al. (1997) Nature 388:171–174]. Comparatively, musical training, another type of sensory enrichment, translates to expertise in cognitive processing and refined biological processing of sound in both cortical and subcortical structures. Therefore, we asked whether bilingualism can also promote experience-dependent plasticity in subcortical auditory processing. We found that adolescent bilinguals, listening to the speech syllable [da], encoded the stimulus more robustly than age-matched monolinguals. Specifically, bilinguals showed enhanced encoding of the fundamental frequency, a feature known to underlie pitch perception and grouping of auditory objects. This enhancement was associated with executive function advantages. Thus, through experience-related tuning of attention, the bilingual auditory system becomes highly efficient in automatically processing sound. This study provides biological evidence for system-wide neural plasticity in auditory experts that facilitates a tight coupling of sensory and cognitive functions.

Reunion of Bownds' Vision Laboratory

Before I started the thread of reading and writing that led to this MindBlog, I spent 35 years doing laboratory experiments on how the rods and cones or our retinas change light into a nerve signal. Next weekend, on the occasion of my 70th birthday, many of the researchers, graduate students, and postdoctoral students who passed through my laboratory are assembling back here in Madison for a laboratory reunion. For this reunion I've pasted together some laboratory history showing pictures, listing contributions, etc., and thought I would pass it on for MindBlog readers who might be curious about my past.

Emotion reversed in the brains of left handers.

Fascinating observations from Brookshire and Casasanto:

According to decades of research on affective motivation in the human brain, approach motivational states are supported primarily by the left hemisphere and avoidance states by the right hemisphere. The underlying cause of this specialization, however, has remained unknown. Here we conducted a first test of the Sword and Shield Hypothesis (SSH), according to which the hemispheric laterality of affective motivation depends on the laterality of motor control for the dominant hand (i.e., the “sword hand," used preferentially to perform approach actions) and the nondominant hand (i.e., the “shield hand," used preferentially to perform avoidance actions).

To determine whether the laterality of approach motivation varies with handedness, we measured alpha-band power (an inverse index of neural activity) in right- and left-handers during resting-state electroencephalography and analyzed hemispheric alpha-power asymmetries as a function of the participants' trait approach motivational tendencies. Stronger approach motivation was associated with more left-hemisphere activity in right-handers, but with more right-hemisphere activity in left-handers.

The hemispheric correlates of approach motivation reversed between right- and left-handers, consistent with the way they typically use their dominant and nondominant hands to perform approach and avoidance actions. In both right- and left-handers, approach motivation was lateralized to the same hemisphere that controls the dominant hand. This covariation between neural systems for action and emotion provides initial support for the SSH.

Compounds that increase muscle endurance also enhance cognition

Recent experiments from Kobilo et al. build on several studies that have shown that exercise enhances cognition (in both humans and mice). They show that giving sedentary mice either of two drugs that induce the same kinds of changes in their muscles that exercise does enhances their performance in subsequent tests of memory and learning. Since these drugs do not cross the blood-brain barrier, peripheral triggers appear be activating the cellular and molecular cascades in the brain that lead to improvements in cognition.

Physical activity improves learning and hippocampal neurogenesis. It is unknown whether compounds that increase endurance in muscle also enhance cognition. We investigated the effects of endurance factors, peroxisome proliferator-activated receptor δ agonist GW501516 and AICAR, activator of AMP-activated protein kinase on memory and neurogenesis. Mice were injected with GW for 7 d or AICAR for 7 or 14 d. Two weeks thereafter mice were tested in the Morris water maze. AICAR (7 d) and GW improved spatial memory. Moreover, AICAR significantly, and GW modestly, elevated dentate gyrus neurogenesis. Thus, pharmacological activation of skeletal muscle may mediate cognitive effects.

Universality of facial expressions of emotion challenged.

This  work by Jack et al (open access to full article) comes as quite a challenge to the prevailing orthodoxy on the universality of human facial movements associated with the six basic emotional states:

Since Darwin’s seminal works, the universality of facial expressions of emotion has remained one of the longest standing debates in the biological and social sciences. Briefly stated, the universality hypothesis claims that all humans communicate six basic internal emotional states (happy, surprise, fear, disgust, anger, and sad) using the same facial movements by virtue of their biological and evolutionary origins [Susskind JM, et al. (2008) Nat Neurosci 11:843–850]. Here, we refute this assumed universality. Using a unique computer graphics platform that combines generative grammars [Chomsky N (1965) MIT Press, Cambridge, MA] with visual perception, we accessed the mind’s eye of 30 Western and Eastern culture individuals and reconstructed their mental representations of the six basic facial expressions of emotion. Cross-cultural comparisons of the mental representations challenge universality on two separate counts. First, whereas Westerners represent each of the six basic emotions with a distinct set of facial movements common to the group, Easterners do not. Second, Easterners represent emotional intensity with distinctive dynamic eye activity. By refuting the long-standing universality hypothesis, our data highlight the powerful influence of culture on shaping basic behaviors once considered biologically hardwired. Consequently, our data open a unique nature–nurture debate across broad fields from evolutionary psychology and social neuroscience to social networking via digital avatars.

Linking social environment to gene expression.

Tung et al. report work on rhesus macaque monkeys - consonant with more limited human studies - showing that dominance rank causes a plastic imprint on regulation of immune system genes. They find that social status can be predicted by gene expression data with 80% accuracy.

Variation in the social environment is a fundamental component of many vertebrate societies. In humans and other primates, adverse social environments often translate into lasting physiological costs. The biological mechanisms associated with these effects are therefore of great interest, both for understanding the evolutionary impacts of social behavior and in the context of human health. However, large gaps remain in our understanding of the mechanisms that mediate these effects at the molecular level. Here we addressed these questions by leveraging the power of an experimental system that consisted of 10 social groups of female macaques, in which each individual's social status (i.e., dominance rank) could be experimentally controlled. Using this paradigm, we show that dominance rank results in a widespread, yet plastic, imprint on gene regulation, such that peripheral blood mononuclear cell gene expression data alone predict social status with 80% accuracy. We investigated the mechanistic basis of these effects using cell type-specific gene expression profiling and glucocorticoid resistance assays, which together contributed to rank effects on gene expression levels for 694 (70%) of the 987 rank-related genes. We also explored the possible contribution of DNA methylation levels to these effects, and identified global associations between dominance rank and methylation profiles that suggest epigenetic flexibility in response to status-related behavioral cues. Together, these results illuminate the importance of the molecular response to social conditions, particularly in the immune system, and demonstrate a key role for gene regulation in linking the social environment to individual physiology.

Egalitarian behavior and the insula.

Fascinating work from Dawes et al.:

Individuals are willing to sacrifice their own resources to promote equality in groups. These costly choices promote equality and are associated with behavior that supports cooperation in humans, but little is known about the brain processes involved. We use functional MRI to study egalitarian preferences based on behavior observed in the “random income game.” In this game, subjects decide whether to pay a cost to alter group members’ randomly allocated incomes. We specifically examine whether egalitarian behavior is associated with neural activity in the ventromedial prefrontal cortex and the insular cortex, two regions that have been shown to be related to social preferences. Consistent with previous studies, we find significant activation in both regions; however, only the insular cortex activations are significantly associated with measures of revealed and expressed egalitarian preferences elicited outside the scanner. These results are consistent with the notion that brain mechanisms involved in experiencing the emotional states of others underlie egalitarian behavior in humans.

From their discussion:

...this experiment shows that some parts of the brain are more active during egalitarian outcomes, and these activations are correlated with egalitarian behavior inside the scanner. However, a more crucial result is that the activations are also correlated with behavior outside the scanner, including self-reported preferences for egalitarian outcomes and game behavior that reveals how willing subjects are to use their own resources to obtain egalitarian outcomes within their groups. Taken together, the evidence suggests that the anterior insular cortex plays a critical role in egalitarian behavior in humans. This conclusion is consistent with a broader view of the insular cortex as a neural substrate that processes the relationship of the individual with respect to his or her environment. The predominately left-lateralized activation may point toward the possibility of a positive valence or energy-preserving mode related processing during egalitarian behavior (i.e., individuals may see the group as a greater good that is worth preserving). The fact that the insula is directly involved in physiological, food, and pain-related processing supports the general notion that prosocial behavior, which is important for survival of both the individual and the group/species, is implemented on a fundamental physiological level similar to breathing, heartbeat, hunger, and pain.

Adam Smith contended that moral sentiments like egalitarianism derived from a “fellow-feeling” that would increase with our level of sympathy for others, predicting not merely aversion to inequity, but also our propensity to engage in egalitarian behaviors. The evidence here supports such an interpretation. Although individuals may experience internal rewards when punishing antisocial behavior and may have preferences for social equality, our results suggest that it is the brain mechanisms involved in experiencing the emotional and social states of self and others that appear to be driving egalitarian behaviors.

Our results have important implications for theories of the evolution of prosocial behavior that suggest culturally transmitted “leveling mechanisms”—for example, food sharing and monogamy—stifle within-group competition and create circumstances in which intergroup antagonism generates selective pressure for altruistic behaviors. A concern for equality may have originally evolved because it fostered the conditions necessary for early human groups to maintain a high level of cooperation. Future research should focus on the interconnectivity of regions of the brain involved in egalitarianism and altruism to better understand how these two behaviors may have coevolved.

Choosing whether you are anxious or chilled out - a toolkit.

This is a followup on my May 2 post, which provided a link to a lecture that I now have given (this past Tuesday) to the Chaos and Complex Systems Seminar series here at UW Madison. Responses to that talk have been very positive. I thought I would suggest that MindBlog readers who want to get quickly to the "bottom line" click straight through the presentation to the fourth part of the talk (4. What are the regulators of calm and stress to which we have conscious access?), which describes a toolkit of "bottom-up" and "top-down" approaches or techniques that can influence whether we are calm or losing it.

The topics:
1. Structures of calm and arousal: What machinery has been cobbled together over evolutionary time? 2. What is going on in our brains and bodies during calm or stress?
3. What is the nature of the self that is having this experience?
4. What are the regulators of calm and stress to which we have conscious access?

12 month old human infants recognize stable social dominance relations.

Interesting work from Mascaro and Csibra. They presented several dominance scenarios with block figures to infants, and then examined mean looking time when the dominance relation that the infant had become familiar with was subsequently violated. In the first study, for example, 9- and 12-mo-old infants were shown short animations depicting the actions of two agents. First, the “subordinate” agent was seen collecting small objects. Then the “dominant” agent entered and started to collect objects while the subordinate one let it succeed. In the second study, Twelve- and 15-mo-old infants watched familiarization events in which the agents did not collect objects but competed to stay in a little area, the boundaries of which were delimited by walls. First, the subordinate agent entered the area alone. Then the dominant agent arrived and monopolized the little area by repeatedly pushing the subordinate agent away. In subsequent viewings these dominance relations were either confirmed or violated. Mean gaze time increased significantly when the familiarized sequence was violated. Here is their abstract:

What are the origins of humans’ capacity to represent social relations? We approached this question by studying human infants’ understanding of social dominance as a stable relation. We presented infants with interactions between animated agents in conflict situations. Studies 1 and 2 targeted expectations of stability of social dominance. They revealed that 15-mo-olds (and, to a lesser extent, 12-mo-olds) expect an asymmetric relationship between two agents to remain stable from one conflict to another. To do so, infants need to infer that one of the agents (the dominant) will consistently prevail when her goals conflict with those of the other (the subordinate). Study 3 and 4 targeted the format of infants’ representation of social dominance. In these studies, we found that 12- and 15-mo-olds did not extend their expectations of dominance to unobserved relationships, even when they could have been established by transitive inference. These results suggest that infants' expectation of stability originates from their representation of social dominance as a relationship between two agents rather than as an individual property. Infants’ demonstrated understanding of social dominance reflects the cognitive underpinning of humans’ capacity to represent social relations, which may be evolutionarily ancient, and may be shared with nonhuman species.

In study 1,

Further work on when two heads are better or worse than one.

Studies that compare the accuracy of individual and group decision yield somewhat inconsistent results. The key to benefiting from other minds is to know when to rely on the group and when to walk alone. To follow up a thread started in two previous posts (here and here) on when two heads are better or worse than one, I pass on this work by Koriat. He shows that in an inference task involving two alternatives, optimal results are obtained with the simple heuristic of selecting the response expressed with the higher—or in the case of more than two heads, highest—degree of confidence. Here is the abstract:

A recent study, using a perceptual task, indicated that two heads were better than one provided that the members could communicate freely, presumably sharing their confidence in their judgments. Capitalizing on recent work on subjective confidence, I replicated this effect in the absence of any dyadic interaction by selecting on each trial the decision of the more confident member of a virtual dyad. However, because subjective confidence monitors the consensuality rather than the accuracy of a decision, when most participants were in error, reliance on the more confident member yielded worse decisions than those of the better individual. Assuming that for each issue group decisions are dominated by the more confident member, these results help specify when groups will be more or less accurate than individuals.

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Brain correlates of whether we help someone suffering.

I thought I would pass on this interesting paper that is being discussed by an emotion seminar group here on the Univ. of Wisc. campus.  Hein et al. touch on the question of whether we are fundamentally good or bad. Is our human nature always fundamentally prosocial?   They find it depends very much on whether we are helping one of "us" or one of "them."  Their summary of the main points, followed by their abstract:

• Empathy-related brain responses in anterior insula predict costly helping
• Helping ingroup and outgroup members is predicted by distinct neural responses
• Brain responses predict behavior toward outgroup members better than self-reports

Little is known about the neurobiological mechanisms underlying prosocial decisions and how they are modulated by social factors such as perceived group membership. The present study investigates the neural processes preceding the willingness to engage in costly helping toward ingroup and outgroup members. Soccer fans witnessed a fan of their favorite team (ingroup member) or of a rival team (outgroup member) experience pain. They were subsequently able to choose to help the other by enduring physical pain themselves to reduce the other's pain. Helping the ingroup member was best predicted by anterior insula activation when seeing him suffer and by associated self-reports of empathic concern. In contrast, not helping the outgroup member was best predicted by nucleus accumbens activation and the degree of negative evaluation of the other. We conclude that empathy-related insula activation can motivate costly helping, whereas an antagonistic signal in nucleus accumbens reduces the propensity to help.