Brain markers of psychopathy.

Philippi et al. analyze 142 adult male prison inmates, and offer a detailed analysis showing that psychopathy can be correlated with altered connectivity in the default mode, frontoparietal, and cingulo-opercular networks. There are no correlations with connectivity in auditory or visual networks. The authors note that "the large and diverse inmate sample affords us a unique opportunity to examine the neural correlates of the two primary “factors” and the four “facets,” or dimensions, of psychopathy. Factor 1 corresponds to the interpersonal/affective traits of psychopathy (e.g., callousness, egocentrism), whereas Factor 2 corresponds to the lifestyle/antisocial features (e.g., impulsivity, irresponsibility). Factor 1 can be further subdivided into Facet 1 (interpersonal traits) and Facet 2 (affective traits), whereas Factor 2 can be further subdivided into Facet 3 (lifestyle traits) and Facet 4 (antisocial traits)." Here is their rather dense and condensed abstract:

Psychopathy is a personality disorder characterized by callous antisocial behavior and criminal recidivism. Here we examine whether psychopathy is associated with alterations in functional connectivity in three large-scale cortical networks. Using fMRI in 142 adult male prison inmates, we computed resting-state functional connectivity using seeds from the default mode network, frontoparietal network, and cingulo-opercular network. To determine the specificity of our findings to these cortical networks, we also calculated functional connectivity using seeds from two comparison primary sensory networks: visual and auditory networks. Regression analyses related network connectivity to overall psychopathy scores and to subscores for the “factors” and “facets” of psychopathy: Factor 1, interpersonal/affective traits; Factor 2, lifestyle/antisocial traits; Facet 1, interpersonal; Facet 2, affective; Facet 3, lifestyle; Facet 4, antisocial. Overall psychopathy severity was associated with reduced functional connectivity between lateral parietal cortex and dorsal anterior cingulate cortex. The two factor scores exhibited contrasting relationships with functional connectivity: Factor 1 scores were associated with reduced functional connectivity in the three cortical networks, whereas Factor 2 scores were associated with heightened connectivity in the same networks. This dissociation was evident particularly in the functional connectivity between anterior insula and dorsal anterior cingulate cortex. The facet scores also demonstrated distinct patterns of connectivity. We found no associations between psychopathy scores and functional connectivity within visual or auditory networks. These findings provide novel evidence on the neural correlates of psychopathy and suggest that connectivity between cortical association hubs, such as the dorsal anterior cingulate cortex, may be a neurobiological marker of the disorder.

Sign language as a window on universals in linguistic representation of events.

From Strickland et al., I've learned a new word - telicity:

According to a theoretical tradition dating back to Aristotle, verbs can be classified into two broad categories. Telic verbs (e.g., “decide,” “sell,” “die”) encode a logical endpoint, whereas atelic verbs (e.g., “think,” “negotiate,” “run”) do not, and the denoted event could therefore logically continue indefinitely. Here we show that sign languages encode telicity in a seemingly universal way and moreover that even nonsigners lacking any prior experience with sign language understand these encodings. In experiments 1–5, nonsigning English speakers accurately distinguished between telic (e.g., “decide”) and atelic (e.g., “think”) signs from (the historically unrelated) Italian Sign Language, Sign Language of the Netherlands, and Turkish Sign Language. These results were not due to participants' inferring that the sign merely imitated the action in question. In experiment 6, we used pseudosigns to show that the presence of a salient visual boundary at the end of a gesture was sufficient to elicit telic interpretations, whereas repeated movement without salient boundaries elicited atelic interpretations. Experiments 7–10 confirmed that these visual cues were used by all of the sign languages studied here. Together, these results suggest that signers and nonsigners share universally accessible notions of telicity as well as universally accessible “mapping biases” between telicity and visual form.

Oxytocin makes formidable men more likeable.

An interesting tidbit from Chen et al.:

Physical size and strength are associated with dominance and threat. The current study tested (i) whether men’s evaluations of male strangers would be negatively influenced by cues indicating physical formidability, and (ii) whether these evaluations would be influenced by oxytocin, a neuropeptide that mediates social behavior and reduces social anxiety. In a placebo-controlled double-blind design, we administered either oxytocin (24 I.U.) or placebo intranasally to 100 healthy males and assessed their responses to an image of either a physically formidable (strong) or physically non-formidable (weak) male peer. Whereas participants receiving placebo expressed dislike and avoidance of the strong male relative to the weak male, oxytocin selectively improved social evaluation of the strong male. These results provide first evidence that oxytocin regulates social evaluation of peers based on body features indicating strength and formidability. We discuss the possibility that oxytocin may promote the expansion of social networks by increasing openness toward potentially threatening individuals.

Serotonin deficiency correlates with stress vulnerability.

From Sachs et al., a statement of significance, followed by a more detailed abstract:

Significance

The biological factors that determine whether an individual develops mental illness, such as depression or posttraumatic stress disorder, or responds adequately to pharmacotherapy remain almost completely unknown. Using genetically modified mice, we demonstrate that low levels of brain serotonin lead to increased vulnerability to psychosocial stress and prevent the antidepressant-like effects of fluoxetine following stress exposure. Our data also show that inhibiting the lateral habenula can reverse stress-induced behavioral avoidance in serotonin-deficient animals, which fail to respond to fluoxetine. Our results provide additional insight into the serotonin deficiency hypothesis of depression and highlight the potential of targeting the lateral habenula to treat depression and anxiety disorders in patients who fail to respond to selective serotonin reuptake inhibitors.

Abstract

Brain serotonin (5-HT) deficiency and exposure to psychosocial stress have both been implicated in the etiology of depression and anxiety disorders, but whether 5-HT deficiency influences susceptibility to depression- and anxiety-like phenotypes induced by psychosocial stress has not been formally established. Most clinically effective antidepressants increase the extracellular levels of 5-HT, and thus it has been hypothesized that antidepressant responses result from the reversal of endogenous 5-HT deficiency, but this hypothesis remains highly controversial. Here we evaluated the impact of brain 5-HT deficiency on stress susceptibility and antidepressant-like responses using tryptophan hydroxylase 2 knockin (Tph2KI) mice, which display 60–80% reductions in brain 5-HT. Our results demonstrate that 5-HT deficiency leads to increased susceptibility to social defeat stress (SDS), a model of psychosocial stress, and prevents the fluoxetine (FLX)-induced reversal of SDS-induced social avoidance, suggesting that 5-HT deficiency may impair antidepressant responses. In light of recent clinical and preclinical studies highlighting the potential of inhibiting the lateral habenula (LHb) to achieve antidepressant and antidepressant-like responses, we also examined whether LHb inhibition could achieve antidepressant-like responses in FLX-insensitive Tph2KI mice subjected to SDS. Our data reveal that using designer receptors exclusively activated by designer drugs (DREADDs) to inhibit LHb activity leads to reduced SDS-induced social avoidance behavior in both WT and Tph2KI mice. This observation provides additional preclinical evidence that inhibiting the LHb might represent a promising alternative therapeutic approach under conditions in which selective 5-HT reuptake inhibitors are ineffective.

The urge to instruct.

I thought I would pass on this humorous piece by Peter Funt on his review of YouTube videos on how to break in a new baseball glove. After reviewing videos on using microwave ovens, jacuzzis, mallets, oil, heat, hot water:

After nearly two hours of viewing, I’ve learned that: (a) it appears no certification is necessary to teach on YouTube; (b) although baseball is the national pastime, no one knows how to break in a glove; and (c) if you accidentally lock a new mitt in an old car, you might be able to use a tennis ball to break in.

This sets me to mulling on what motivates the making of such videos, and indeed, what motives me to pass on or describe articles about mind, brain, and behavior that I have very little real critical insight into. Just as with a kid showing off a new toy, the 'gee whiz' or 'this is neat' moment that comes from encountering a new idea or bit of work is enhanced by sharing it with others.

The "Good Life"

The previous post noting recent work by Dacher Keltner and collaborators prompted me to have another look at the website of "The Greater Good Science Center" at the University of California Berkeley that Keltner and others have established. It has recently developed another website, Greater Good in Action, that offers engaging brief exercises in practices shown by research to enhance and build all sorts of good stuff: connection, empathy, kindness, compassion, forgiveness, gratitude, happiness, optimism, resilience to stress, awe, etc. Just clicking through, and spending maybe 5-10 minutes, on a few of the exercises leaves me with a mushy warm glow of contentment, which persists for varying periods of time until my usual default curmudgeonly self reappears. You might enjoy trying some.

Why do we experience awe?

Awe, like reverence, is a pro-social emotion that subordinates individual self interest to a larger whole. Dacher Keltner and Paul Piff, in their NYTimes piece publicizing of their more academic publication (marketing is a necessity these days) describe five different studies, each providing experimental evidence that awe helps bind us to others, motivating us to be more generous and helpful to strangers, to act in collaborative ways that enable strong groups and cohesive communities. The positive effect of awe on prosociality are partly explained by feelings of a smaller self.

...even brief experiences of awe, such as being amid beautiful tall trees, lead people to feel less narcissistic and entitled and more attuned to the common humanity people share with one another. In the great balancing act of our social lives, between the gratification of self-interest and a concern for others, fleeting experiences of awe redefine the self in terms of the collective, and orient our actions toward the needs of those around us.

You could make the case that our culture today is awe-deprived. Adults spend more and more time working and commuting and less time outdoors and with other people...Attendance at arts events — live music, theater, museums and galleries — has dropped over the years...Arts and music programs in schools are being dismantled in lieu of programs better suited to standardized testing; time outdoors and for novel, unbounded exploration are sacrificed for résumé-building activities.

We believe that awe deprivation has had a hand in a broad societal shift that has been widely observed over the past 50 years: People have become more individualistic, more self-focused, more materialistic and less connected to others. To reverse this trend, we suggest that people insist on experiencing more everyday awe, to actively seek out what gives them goose bumps, be it in looking at trees, night skies, patterns of wind on water or the quotidian nobility of others — the teenage punk who gives up his seat on public transportation, the young child who explores the world in a state of wonder, the person who presses on against all odds.

Lack of exercise disrupts body’s rhythms.

Natural daily rhythms in spontaneous movement patterns in both humans and mice show scale invariance, i.e., movement patterns repeat over time scales of minutes to hours. These scale invariant patterns decay with aging in both humans and mice, apparently correlating with progressive dysfunction of circadian pacemaker circuits in the brain's suprachiasmatic nucleus. Scheer and collaborators have now shown that in both aged and young mice exercise is a crucial variable. Loss of scale invariance associated with both inactivity and aging can be restored by exercise, even in old animals.

In healthy humans and other animals, behavioral activity exhibits scale invariance over multiple timescales from minutes to 24 h, whereas in aging or diseased conditions, scale invariance is usually reduced significantly. Accordingly, scale invariance can be a potential marker for health. Given compelling indications that exercise is beneficial for mental and physical health, we tested to what extent a lack of exercise affects scale invariance in young and aged animals. We studied six or more mice in each of four age groups (0.5, 1, 1.5, and 2 y) and observed an age-related deterioration of scale invariance in activity fluctuations. We found that limiting the amount of exercise, by removing the running wheels, leads to loss of scale-invariant properties in all age groups. Remarkably, in both young and old animals a lack of exercise reduced the scale invariance in activity fluctuations to the same level. We next showed that scale invariance can be restored by returning the running wheels. Exercise during the active period also improved scale invariance during the resting period, suggesting that activity during the active phase may also be beneficial for the resting phase. Finally, our data showed that exercise had a stronger influence on scale invariance than the effect of age. The data suggest that exercise is beneficial as revealed by scale-invariant parameters and that, even in young animals, a lack of exercise leads to strong deterioration in these parameters.

It’s not a stream of consciousness, its a rhythm.

In the NYTimes Gray Matter series Gregory Hickok gives an exegesis on the implications of his Psychological Science paper "The Rhythm of Perception." Some edited clips:

IN 1890, the American psychologist William James famously likened our conscious experience to the flow of a stream...recent research has shown that the “stream” of consciousness is, in fact, an illusion. We actually perceive the world in rhythmic pulses (brain waves that correlate with states like calm alertness and deep sleep) rather than as a continuous flow....We are exploring the possibility that brain rhythms are not merely a reflection of mental activity but a cause of it, helping shape perception, movement, memory and even consciousness itself...What this means is that the brain samples the world in rhythmic pulses, perhaps even discrete time chunks, much like the individual frames of a movie. From the brain’s perspective, experience is not continuous but quantized.

It turns out, for example, that our ability to detect a subtle event, like a slight change in a visual scene, oscillates over time, cycling between better and worse perceptual sensitivity several times a second. Research shows that these rhythms correlate with electrical rhythms of the brain.

If that’s hard to picture, here’s an analogy: Imagine trying to see an animal through a thick, swirling fog that varies in density as it drifts. The distinctness of the animal’s form will oscillate with the density of the fog, alternating between periods of relative clarity and opaqueness. According to recent experiments, this is how our perceptual systems sample the world — but rather than fog, it’s brain waves that drive the oscillations...Rhythms in the environment, such as those in music or speech, can draw neural oscillations into their tempo, effectively synchronizing the brain’s rhythms with those of the world around us.

In the study reported in Psychological Science Hickok and colleagues:

...presented listeners with a three-beat-per-second rhythm (a pulsing “whoosh” sound) for only a few seconds and then asked the listeners to try to detect a faint tone immediately afterward. The tone was presented at a range of delays between zero and 1.4 seconds after the rhythm ended. Not only did we find that the ability to detect the tone varied over time by up to 25 percent — that’s a lot — but it did so precisely in sync with the previously heard three-beat-per-second rhythm.

Why would the brain do this? One theory is that it’s the brain’s way of focusing attention. Picture a noisy cafe filled with voices, clanging dishes and background music. As you attend to one particular acoustic stream — say, your lunch mate’s voice — your brain synchronizes its rhythm to the rhythm of the voice and enhances the perceptibility of that stream, while suppressing other streams, which have their own, different rhythms. (More broadly, this kind of synchronization has been proposed as a mechanism for communication between neural networks within the brain.)

All of this points to the need for a new metaphor. We should talk of the “rhythm” of thought, of perception, of consciousness. Conceptualizing our mental experience this way is not only more accurate, but it also situates our mind within the broader context of the daily, monthly and yearly rhythms that dominate our lives.

Humans need not apply.

Check out this chilling video on the increasing obsolescence of humans, which was referenced in a recent meeting of the Chaos and Complexity Seminar group I attend at the University of Wisconsin (when I am in Madison during the warm months). Then note the partial solace offered by Carr's essay "Why Robots Will Always Need Us."

How we fashion meaning and purpose.

This is a brief post about some material I thought I might get to cohere, maybe something along the lines of purpose as an evolved means of generating order, part of the big story of order evolving from chaos in the universe. I was wrong about the coherence, but I think the links are worth mentioning. The “Big History Project” is an effort to generate a modern origin story that transcends previous stories because it is global. From David Christian:

...in modern science we've gotten used to the idea that science doesn't offer meaning in the way that institutional religions did in the past. I'm increasingly thinking that this idea that modernity puts us in a world without meaning….may be completely wrong. We may be living in an intellectual building site, where a new story is being constructed. It's vastly more powerful than the previous stories because it's the first one that is global. It's not anchored in a particular culture or a particular society. This is an origin story that works for humans in Beijing as well as in Buenos Aires...it sums over vastly more information than any early origin story….across so many domains, the amount of information, of good, rigorous ideas, is so rich that we can tease out that story.

The Christian's Big History project reminds me of the Natural Sciences 5 course originated by my mentor George Wald, which I taught in when I was a Harvard senior and then graduate student in 1963-67. These efforts have started with cosmology, the origin of the university, the solar systems and earth, the appearance and evolution of life, and finally the human story. I had a look at Chapter 5 of the online Big History Project (aimed at middle and high school level, 13-17 year olds) and found it reasonably engaging.


The second source I want to mention is a piece by Worthen titled "Wanted: A Theology of Atheism." The title is an oxymoron [Greek Theos (god) + logia (subject of study)], presumably intentional. It discusses efforts, of the sort described in some previous MindBlog posts, to form secular (godless) forums, churches, or assemblies that meet our human need for communal settings that reinforce kindness and moral behavior, that balance the needs of the community against self interest. Worthen quotes Sam Harris's:

...promoting science as a universal moral guide. This proposal is an old one. The 19th-century French philosopher Auguste Comte and the American intellectuals Walter Lippmann and John Dewey all wrote that moral progress depended on the scientific method.

Morality depends on “the totality of facts that relate to human well-being, and our knowledge of it grows the more we learn about ourselves, in fields ranging from molecular biology to economics,” Harris has stressed the special role of his own field, cognitive science. Every discovery about the brain’s experience of pleasure and suffering has implications for how we should treat other humans. Moral philosophy is really an “undeveloped branch of science” whose laws apply in Peoria just as they do in the Punjab.

Pragmatist philosophers like Philip Kitcher offer a different approach to the question of atheist morality, one based on “the sense that ethical life grows out of our origins, the circumstances under which our ancestors lived, and it’s a work in progress,” he said. In the pragmatist tradition, science is useful, but ethical claims are not objective scientific facts. They are only “true” if they seem to “work” in real life.

Sleep stabilizes, but does not enhance, motor performance training.

From Nettersheim et al., a result challenging the prominent model that sleep enhances the performance of a newly learned skill (which is my experience in learning difficulat new piano passages):

Sleep supports the consolidation of motor sequence memories, yet it remains unclear whether sleep stabilizes or actually enhances motor sequence performance. Here we assessed the time course of motor memory consolidation in humans, taking early boosts in performance into account and varying the time between training and sleep. Two groups of subjects, each participating in a short wake condition and a longer sleep condition, were trained on the sequential finger-tapping task in the evening and were tested (1) after wake intervals of either 30 min or 4 h and (2) after a night of sleep that ensued either 30 min or 4 h after training. The results show an early boost in performance 30 min after training and a subsequent decay across the 4 h wake interval. When sleep followed 30 min after training, post-sleep performance was stabilized at the early boost level. Sleep at 4 h after training restored performance to the early boost level, such that, 12 h after training, performance was comparable regardless of whether sleep occurred 30 min or 4 h after training. These findings indicate that sleep does not enhance but rather stabilizes motor sequence performance without producing additional gains.

Cultural differences, emotional expressivity, and smiles

Rychlowska et al. analyze cultural display rules from 32 countries to reveal that the extent to which a country’s present-day population descends from numerous versus few source countries is associated with norms favoring greater emotional expressivity.

A small number of facial expressions may be universal in that they are produced by the same basic affective states and recognized as such throughout the world. However, other aspects of emotionally expressive behavior vary widely across culture. Just why do they vary? We propose that some cultural differences in expressive behavior are determined by historical heterogeneity, or the extent to which a country’s present-day population descended from migration from numerous vs. few source countries over a period of 500 y. Our reanalysis of data on cultural rules for displaying emotion from 32 countries reveals that historical heterogeneity explains substantial, unique variance in the degree to which individuals believe that emotions should be openly expressed. We also report an original study of the underlying states that people believe are signified by a smile. Cluster analysis applied to data from nine countries, including Canada, France, Germany, India, Indonesia, Israel, Japan, New Zealand, and the United States, reveals that countries group into “cultures of smiling” determined by historical heterogeneity. Factor analysis shows that smiles sort into three social-functional subtypes: pleasure, affiliative, and dominance. The relative importance of these smile subtypes varies as a function of historical heterogeneity. These findings thus highlight the power of social-historical factors to explain cross-cultural variation in emotional expression and smile behavior.

How biased are our brains?

Kristof reviews some recent work on unconscious bias, particularly racial bias.

Scholars suggest that in evolutionary times we became hard-wired to make instantaneous judgments about whether someone is in our “in group” or not — because that could be lifesaving. A child who didn’t prefer his or her own group might have been at risk of being clubbed to death...tests of unconscious biases... suggest that people turn out to have subterranean racial and gender biases that they are unaware of and even disapprove of.

I thought I would point out a recently published book, the subject of a forthcoming multiple review in Behavioral and Brain Sciences, which argues that the power of biases on perception is usually overstated, that perceptions of individuals and groups tend to be accurate. The précis of the book can be downloaded here. Book title and abstract:

Lee Jussim - Social Perception and Social Reality: Why Accuracy Dominates Bias and Self-Fulfilling Prophecy (Oxford University Press, 2012)

Abstract: Social Perception and Social Reality reviews the evidence in social psychology and related fields and reaches three conclusions: 1. Although errors, biases, and self-fulfilling prophecies in person perception, are real, reliable, and occasionally quite powerful, on average, they tend to be weak, fragile and fleeting; 2. Perceptions of individuals and groups tend to be at least moderately, and often highly accurate; and 3. Conclusions based on the research on error, bias, and self-fulfilling prophecies routinely greatly overstates their power and pervasiveness, and consistently ignores evidence of accuracy, agreement, and rationality in social perception. The weight of the evidence - including some of the most classic research widely interpreted as testifying to the power of biased and self-fulfilling processes - is that interpersonal expectations related to social reality primarily because they reflect rather than cause social reality. This is the case not only of teacher expectations, but also social stereotypes, both as perceptions of groups, and as the bases of expectations regarding individuals. The time is long overdue to replace cherry-picked and unjustified stories emphasizing error, bias, the power of self-fulfilling prophecies and the inaccuracy of stereotypes with conclusions that more closely correspond to the full range of empirical findings, which includes multiple failed replications of classic expectancy studies, meta-analyses consistently demonstrating small or at best moderate expectancy effects, and high accuracy in social perception.

After Phrenology: Neural Reuse and the Interactive Brain

I've been reading through an interesting article by Michael Anderson, a précis of a book accepted for publication and available as a PDF through BBS. I pass on the abstract:

Neural reuse is a form of neuroplasticity whereby neural elements originally developed for one purpose are put to multiple uses. A diverse behavioral repertoire is achieved via the creation of multiple, nested, and overlapping neural coalitions, in which each neural element is a member of multiple different coalitions and cooperates with a different set of partners at different times. This has profound implications for how we think about our continuity with other species, for how we understand the similarities and differences between psychological processes, and for how best to pursue a unified science of the mind. After Phrenology surveys the terrain and advocates for a series of reforms in psychology and cognitive neuroscience. The book argues that, among other things, we should capture brain function in a multi-dimensional manner, develop a new, action-oriented vocabulary for psychology, and recognize that higher-order cognitive processes are built from complex configurations of already evolved circuitry.

Neural basis of anxiety reduction by placebo.

Meyer et al. directly measure neural consequences of expecting a placebo treatment to be effective in relieving anxiety:

The beneficial effects of placebo treatments on fear and anxiety (placebo anxiolysis) are well known from clinical practice, and there is strong evidence indicating a contribution of treatment expectations to the efficacy of anxiolytic drugs. Although clinically highly relevant, the neural mechanisms underlying placebo anxiolysis are poorly understood. In two studies in humans, we tested whether the administration of an inactive treatment along with verbal suggestions of anxiolysis can attenuate experimentally induced states of phasic fear and/or sustained anxiety. Phasic fear is the response to a well defined threat and includes attentional focusing on the source of threat and concomitant phasic increases of autonomic arousal, whereas in sustained states of anxiety potential and unclear danger requires vigilant scanning of the environment and elevated tonic arousal levels. Our placebo manipulation consistently reduced vigilance measured in terms of undifferentiated reactivity to salient cues (indexed by subjective ratings, skin conductance responses and EEG event-related potentials) and tonic arousal [indexed by cue-unrelated skin conductance levels and enhanced EEG alpha (8–12 Hz) activity], indicating a downregulation of sustained anxiety rather than phasic fear. We also observed a placebo-dependent sustained increase of frontal midline EEG theta (4–7 Hz) power and frontoposterior theta coupling, suggesting the recruitment of frontally based cognitive control functions. Our results thus support the crucial role of treatment expectations in placebo anxiolysis and provide insight into the underlying neural mechanisms.

How alarm amplifies through social networks.

We've all probably played the parlor game with 10 or more people sitting in a circle, with one whispering a word into the ear of the person to their right, continuing to pass the word by whispering to the right until it comes back to the originator, frequently altered from its original form. Moussaïd et al. do a version of this routine in an experiment on how risk perception of hazardous events such as contagious outbreaks, terrorist attacks, and climate change spread through social networks. They find that although the content of a message is gradually lost over repeated social transmissions, subjective perceptions of risk propagate and amplify due to social influence.

Understanding how people form and revise their perception of risk is central to designing efficient risk communication methods, eliciting risk awareness, and avoiding unnecessary anxiety among the public. However, public responses to hazardous events such as climate change, contagious outbreaks, and terrorist threats are complex and difficult-to-anticipate phenomena. Although many psychological factors influencing risk perception have been identified in the past, it remains unclear how perceptions of risk change when propagated from one person to another and what impact the repeated social transmission of perceived risk has at the population scale. Here, we study the social dynamics of risk perception by analyzing how messages detailing the benefits and harms of a controversial antibacterial agent undergo change when passed from one person to the next in 10-subject experimental diffusion chains. Our analyses show that when messages are propagated through the diffusion chains, they tend to become shorter, gradually inaccurate, and increasingly dissimilar between chains. In contrast, the perception of risk is propagated with higher fidelity due to participants manipulating messages to fit their preconceptions, thereby influencing the judgments of subsequent participants. Computer simulations implementing this simple influence mechanism show that small judgment biases tend to become more extreme, even when the injected message contradicts preconceived risk judgments. Our results provide quantitative insights into the social amplification of risk perception, and can help policy makers better anticipate and manage the public response to emerging threats.

Modulating movement intention and the extended present with tDCS.

Douglas et al. do a fascinating bit of work on the 'extended present' in which our brains function, during which our experienced intention to make a movement actually comes ~200 milliseconds after motor cortex signals initiating the movement (the famous Libet experiment showing we are 'late to action'). Conscious intention, or volition, provides the foundation for our attributing agency to ourselves, and for society attributing responsibility to an individual. A distorted sense of volition is a hallmark of many neurological and psychiatric illnesses such as alien hand syndrome, psychogenic movement disorders, and schizophrenia.

Conscious intention is a fundamental aspect of the human experience. Despite long-standing interest in the basis and implications of intention, its underlying neurobiological mechanisms remain poorly understood. Using high-definition transcranial DC stimulation (tDCS), we observed that enhancing spontaneous neuronal excitability in both the angular gyrus and the primary motor cortex caused the reported time of conscious movement intention to be ∼60–70 ms earlier. Slow brain waves recorded ∼2–3 s before movement onset, as well as hundreds of milliseconds after movement onset, independently correlated with the modulation of conscious intention by brain stimulation. These brain activities together accounted for 81% of interindividual variability in the modulation of movement intention by brain stimulation. A computational model using coupled leaky integrator units with biophysically plausible assumptions about the effect of tDCS captured the effects of stimulation on both neural activity and behavior. These results reveal a temporally extended brain process underlying conscious movement intention that spans seconds around movement commencement.

Brain correlates of loving kindness meditation.

Garrison and collaborators extend their work on brain correlates of meditation practice, noting again a central role for the posterior cingulate cortex/precuneus (for previous posts in this thread, enter "Garrison" in the MindBlog search box in the left column).

Loving kindness is a form of meditation involving directed well-wishing, typically supported by the silent repetition of phrases such as “may all beings be happy,” to foster a feeling of selfless love. Here we used functional magnetic resonance imaging to assess the neural substrate of loving kindness meditation in experienced meditators and novices. We first assessed group differences in blood oxygen level-dependent (BOLD) signal during loving kindness meditation. We next used a relatively novel approach, the intrinsic connectivity distribution of functional connectivity, to identify regions that differ in intrinsic connectivity between groups, and then used a data-driven approach to seed-based connectivity analysis to identify which connections differ between groups. Our findings suggest group differences in brain regions involved in self-related processing and mind wandering, emotional processing, inner speech, and memory. Meditators showed overall reduced BOLD signal and intrinsic connectivity during loving kindness as compared to novices, more specifically in the posterior cingulate cortex/precuneus (PCC/PCu), a finding that is consistent with our prior work and other recent neuroimaging studies of meditation. Furthermore, meditators showed greater functional connectivity during loving kindness between the PCC/PCu and the left inferior frontal gyrus, whereas novices showed greater functional connectivity during loving kindness between the PCC/PCu and other cortical midline regions of the default mode network, the bilateral posterior insula lobe, and the bilateral parahippocampus/hippocampus. These novel findings suggest that loving kindness meditation involves a present-centered, selfless focus for meditators as compared to novices.

Essentialism

I pass on some clips from Richard Dawkins' brief essay, and suggest you also take a look at Lisa Barrett's comments on essentialist views of the mind:

Essentialism—what I’ve called "the tyranny of the discontinuous mind"—stems from Plato, with his characteristically Greek geometer’s view of things. For Plato, a circle, or a right triangle, were ideal forms, definable mathematically but never realised in practice. A circle drawn in the sand was an imperfect approximation to the ideal Platonic circle hanging in some abstract space. That works for geometric shapes like circles, but essentialism has been applied to living things and Ernst Mayr blamed this for humanity’s late discovery of evolution—as late as the nineteenth century. If, like Aristotle, you treat all flesh-and-blood rabbits as imperfect approximations to an ideal Platonic rabbit, it won’t occur to you that rabbits might have evolved from a non-rabbit ancestor, and might evolve into a non-rabbit descendant. If you think, following the dictionary definition of essentialism, that the essence of rabbitness is "prior to" the existence of rabbits (whatever "prior to" might mean, and that’s a nonsense in itself) evolution is not an idea that will spring readily to your mind, and you may resist when somebody else suggests it.

Essentialism rears its ugly head in racial terminology. The majority of "African Americans" are of mixed race. Yet so entrenched is our essentialist mind-set, American official forms require everyone to tick one race/ethnicity box or another: no room for intermediates. A different but also pernicious point is that a person will be called "African American" even if only, say, one of his eight great grandparents was of African descent. As Lionel Tiger put it to me, we have here a reprehensible "contamination metaphor." But I mainly want to call attention to our society’s essentialist determination to dragoon a person into one discrete category or another. We seem ill-equipped to deal mentally with a continuous spectrum of intermediates. We are still infected with the plague of Plato’s essentialism.

Moral controversies such as those over abortion and euthanasia are riddled with the same infection. At what point is a brain-dead accident-victim defined as "dead"? At what moment during development does an embryo become a "person"? Only a mind infected with essentialism would ask such questions. An embryo develops gradually from single-celled zygote to newborn baby, and there’s no one instant when "personhood" should be deemed to have arrived. The world is divided into those who get this truth and those who wail, "But there has to be some moment when the fetus becomes human." No, there really doesn’t, any more than there has to be a day when a middle aged person becomes old. It would be better—though still not ideal—to say the embryo goes through stages of being a quarter human, half human, three quarters human . . . The essentialist mind will recoil from such language and accuse me of all manner of horrors for denying the essence of humanness...Our essentialist urge toward rigid definitions of "human" (in debates over abortion and animal rights) and "alive" (in debates over euthanasia and end-of-life decisions) makes no sense in the light of evolution and other gradualistic phenomena.

We define a poverty "line": you are either "above" or "below" it. But poverty is a continuum. Why not say, in dollar-equivalents, how poor you actually are? The preposterous Electoral College system in US presidential elections is another, and especially grievous, manifestation of essentialist thinking. Florida must go either wholly Republican or wholly Democrat—all 25 Electoral College votes—even though the popular vote is a dead heat. But states should not be seen as essentially red or blue: they are mixtures in various proportions.

You can surely think of many other examples of "the dead hand of Plato"—essentialism. It is scientifically confused and morally pernicious. It needs to be retired.