Joseph et al. offer a review of recent work showing that dietary changes favoring berry fruit, nut, fish oil, and curcumin intake, as well as and caloric restriction mimetics (such as resveratrol) may provide beneficial effects in aging and prevent or delay the onset of neurodegenerative diseases such as Alzheimer disease. While many of the mechanisms for the beneficial effects of these nutritional interventions have yet to be discerned, it is clear that they involve decreases in oxidative/inflammatory stress signaling, increases in protective signaling, and may even involve hormetic effects to protect against the two major villains of aging, oxidative and inflammatory stressors. (Hormetic is a term used to describe generally-favorable biological responses to low exposures to toxins and other stressors.)
Monday, November 30, 2009
Rizzolatti and colleagues carry the mirror neuron story to an even higher level in a study of regret:
Previous studies showed that the understanding of others' basic emotional experiences is based on a “resonant” mechanism, i.e., on the reactivation, in the observer's brain, of the cerebral areas associated with those experiences. The present study aimed to investigate whether the same neural mechanism is activated both when experiencing and attending complex, cognitively-generated, emotions. A gambling task and functional-Magnetic-Resonance-Imaging (fMRI) were used to test this hypothesis using regret, the negative cognitively-based emotion resulting from an unfavorable counterfactual comparison between the outcomes of chosen and discarded options. Do the same brain structures that mediate the experience of regret become active in the observation of situations eliciting regret in another individual? Here we show that observing the regretful outcomes of someone else's choices activates the same regions that are activated during a first-person experience of regret, i.e. the ventromedial prefrontal cortex, anterior cingulate cortex and hippocampus. These results extend the possible role of a mirror-like mechanism beyond basic emotions.
Friday, November 27, 2009
In a NYTimes OpEd piece appropriate to yesterday's Thanksgiving rituals Kristof notes a new crop of books on religion that that he feels are less combative and more thoughtful than extreme fundamentalist (The "Left Behind" novels) or atheist (Dawkins, Harris, Hitchens) efforts.
One of these is “The Evolution of God,” by Robert Wright, who explores how religions have changed — improved — over the millennia. He notes that God, as perceived by humans, has mellowed from the capricious warlord sometimes depicted in the Old Testament who periodically orders genocides...Karen Armstrong’s “The Case for God,” likewise doesn’t posit a Grandpa-in-the-Sky; rather, she sees God in terms of an ineffable presence that can be neither proven nor disproven in any rational sense. To Ms. Armstrong, faith belongs to the realm of life’s mysteries, beyond the world of reason, and people on both sides of the “God gap” make the mistake of interpreting religious traditions too literally...“The Faith Instinct,” by...Nicholas Wade, suggests a reason for the durability of faith: humans may be programmed for religious belief, because faith conferred evolutionary advantages in primitive times. That doesn’t go to the question of whether God exists, but it suggests that religion in some form may be with us for eons to come.
Acerbi et al. ask what might make different groups of people more liberal or conservative (or open minded versus having inflexible views), and develop a model which shows that cultural evolution can maintain openness to new information as well as effectiveness at cultural transmission. They consider how rules of cultural transmission can be modified by social learning. For example, individuals might learn from others whether or not to rely on social information. Their model predicts smaller societies to be more conservative, which agrees with the observation that traditional societies (whose very name implies conservatism) tend to be small. It is consistent with archaeological evidence showing that large cultural repertoires can be maintained only by large groups.
We present a model of cultural evolution in which an individual's propensity to engage in social learning is affected by social learning itself. We assume that individuals observe cultural traits displayed by others and decide whether to copy them based on their overall preference for the displayed traits. Preferences, too, can be transmitted between individuals. Our results show that such cultural dynamics tends to produce conservative individuals, i.e., individuals who are reluctant to copy new traits. Openness to new information, however, can be maintained when individuals need significant time to acquire the cultural traits that make them effective cultural models. We show that a gradual enculturation of young individuals by many models and a larger cultural repertoire to be acquired are favorable circumstances for the long-term maintenance of openness in individuals and groups. Our results agree with data about lifetime personality change, showing that openness to new information decreases with age. Our results show that cultural remodeling of cultural transmission is a powerful force in cultural evolution, i.e., that cultural evolution can change its own dynamics.
I want to point you to this great post at Neuroskeptic. Here is its ending text:
"The placebo effect" has become a vague catch-all term for anything that seems to happen to people when you give them a sugar pill. Of course, lots of things could happen. They could feel better just because of the passage of time. Or they could realize that they're supposed to feel better and say they feel better, even if they don't.
The "true" placebo effect refers to improvement (or worsening) of symptoms driven purely by the psychological expectation of such. But even this is something of a catch-all term. Many things could drive this improvement. Suppose you give someone a placebo pill that you claim will make them more intelligent, and they believe it.
Believing themselves to be smarter, they start doing smart things like crosswords, math puzzles, reading hard books (or even reading Neuroskeptic), etc. But the placebo itself was just a nudge in the right direction. Anything which provided that nudge would also have worked - and the nudge itself can't take all the credit.
The strongest meaning of the "placebo effect" is a direct effect of belief upon symptoms. You give someone a sugar pill or injection, and they immediately feel less pain, or whatever. But even this effect encompasses two kinds of things. It's one thing if the original symptoms have a "real" medical cause, like a broken leg. But it's another thing if the original symptoms are themselves partially or wholly driven by psychological factors, i.e. if they are "psychosomatic".
If a placebo treats a "psychosomatic" disease, then that's not because the placebo has some mysterious, mind-over-matter "placebo effect". All the mystery, rather, lies with the psychosomatic disease. But this is a crucial distinction.
People seem more willing to accept the mind-over-matter powers of "the placebo" than they are to accept the existence of psychosomatic illness. As if only doctors with sugar pills possess the power of suggestion. If a simple pill can convince someone that they are cured, surely the modern world in all its complexity could convince people that they're ill.
Thursday, November 26, 2009
Yet another lucidly presented bit of work from a collaboration involving Dolan's group at University College London:
The maxim "no pain, no gain" summarizes scenarios in which an action leading to reward also entails a cost. Although we know a substantial amount about how the brain represents pain and reward separately, we know little about how they are integrated during goal-directed behavior. Two theoretical models might account for the integration of reward and pain. An additive model specifies that the disutility of costs is summed linearly with the utility of benefits, whereas an interactive model suggests that cost and benefit utilities interact so that the sensitivity to benefits is attenuated as costs become increasingly aversive. Using a novel task that required integration of physical pain and monetary reward, we examined the mechanism underlying cost–benefit integration in humans. We provide evidence in support of an interactive model in behavioral choice. Using functional neuroimaging, we identify a neural signature for this interaction such that, when the consequences of actions embody a mixture of reward and pain, there is an attenuation of a predictive reward signal in both ventral anterior cingulate cortex and ventral striatum. We conclude that these regions subserve integration of action costs and benefits in humans, a finding that suggests a cross-species similarity in neural substrates that implement this function and illuminates mechanisms that underlie altered decision making under aversive conditions.
Here is another bit on music or musicians. (I seem to be doing a fair number of postings in this area, maybe because I'm back into more hard core piano playing since returning to Fort Lauderdale...my hands are fatigued after 3 hours of Dvorak and Dohnanyi piano quintets yesterday.) Rosenkranz et al. show that an overly expanded spatial integration of proprioceptive input into the hand motor cortex that can cause deficiencies in hand motor controls (dystonia) can be reversed by proprioceptive training in pianists with musician's dystonia to the pattern seen in healthy pianists. (The training intervention requires the subject's attention to be focused for 15 min on random vibrations delivered to three hand muscles.):
Professional musicians are an excellent model of long-term motor learning effects on structure and function of the sensorimotor system. However, intensive motor skill training has been associated with task-specific deficiency in hand motor control, which has a higher prevalence among musicians (musician's dystonia) than in the general population. Using a transcranial magnetic stimulation paradigm, we previously found an expanded spatial integration of proprioceptive input into the hand motor cortex [sensorimotor organization (SMO)] in healthy musicians. In musician's dystonia, however, this expansion was even larger. Whereas motor skills of musicians are likely to be supported by a spatially expanded SMO, we hypothesized that in musician's dystonia this might have developed too far and now disrupts rather than assists task-specific motor control. If so, motor control should be regained by reversing the excessive reorganization in musician's dystonia. Here, we test this hypothesis and show that a 15 min intervention with proprioceptive input (proprioceptive training) restored SMO in pianists with musician's dystonia to the pattern seen in healthy pianists. Crucially, task-specific motor control improved significantly and objectively as measured with a MIDI (musical instrument digital interface) piano, and the amount of behavioral improvement was significantly correlated to the degree of sensorimotor reorganization. In healthy pianists and nonmusicians, the SMO and motor performance remained essentially unchanged. These findings suggest that the differentiation of SMO in the hand motor cortex and the degree of motor control of intensively practiced tasks are significantly linked and finely balanced. Proprioceptive training restored this balance in musician's dystonia to the behaviorally beneficial level of healthy musicians.
Wednesday, November 25, 2009
Natalie Angier does a summary of some recent studies on oxytocin, several of which I've already mentioned in MindBlog posts (enter oxytocin in the search box to list them). Of particular interest is recent work from Keltner's group showing that genetic differences in people’s responsiveness to the effects of oxytocin are linked to their ability to read faces, infer the emotions of others, feel distress at others’ hardship and even to identify with characters in a novel. Here is the abstract from the Keltner group:
Oxytocin, a peptide that functions as both a hormone and neurotransmitter, has broad influences on social and emotional processing throughout the body and the brain. In this study, we tested how a polymorphism (rs53576) of the oxytocin receptor relates to two key social processes related to oxytocin: empathy and stress reactivity. Compared with individuals homozygous for the G allele of rs53576 (GG), individuals with one or two copies of the A allele (AG/AA) exhibited lower behavioral and dispositional empathy, as measured by the “Reading the Mind in the Eyes” Test and an other-oriented empathy scale. Furthermore, AA/AG individuals displayed higher physiological and dispositional stress reactivity than GG individuals, as determined by heart rate response during a startle anticipation task and an affective reactivity scale. Our results provide evidence of how a naturally occurring genetic variation of the oxytocin receptor relates to both empathy and stress profiles.
Interesting observations by Palagi et al:
Yawn contagion in humans has been proposed to be related to our capacity for empathy. It is presently unclear whether this capacity is uniquely human or shared with other primates, especially monkeys. Here, we show that in gelada baboons (Theropithecus gelada) yawning is contagious between individuals, especially those that are socially close, i.e., the contagiousness of yawning correlated with the level of grooming contact between individuals. This correlation persisted after controlling for the effect of spatial association. Thus, emotional proximity rather than spatial proximity best predicts yawn contagion. Adult females showed precise matching of different yawning types, which suggests a mirroring mechanism that activates shared representations. The present study also suggests that females have an enhanced sensitivity and emotional tuning toward companions. These findings are consistent with the view that contagious yawning reveals an emotional connection between individuals. This phenomenon, here demonstrated in monkeys, could be a building block for full-blown empathy.
Three different yawning displays performed by gelada baboons. Covered teeth yawning (left) uncovered teeth yawning (middle). and uncovered gums yawning (right).
Tuesday, November 24, 2009
Rudoy et al. (PDF here) find that if, while asleep, people hear sounds that had earlier been associated with objects at specific spatial locations, upon waking they recalled these locations more accurately than other locations for which no reminder cues were provided. Consolidation thus operates during sleep with high specificity and is subject to systematic influences through simple auditory stimulation.
Steven Mithen (author of The Singing Neanderthals) does a summary of his ideas on the evolutionary basis of musicality in this open access article in the Annals of the New York Academy of Sciences.
Why does music pervade our lives and those of all known human beings living today and in the recent past? Why do we feel compelled to engage in musical activity, or at least simply enjoy listening to music even if we choose not to actively participate? I argue that this is because musicality—communication using variations in pitch, rhythm, dynamics and timbre, by a combination of the voice, body (as in dance), and material culture—was essential to the lives of our pre-linguistic hominin ancestors. As a consequence we have inherited a desire to engage with music, even if this has no adaptive benefit for us today as a species whose communication system is dominated by spoken language. In this article I provide a summary of the arguments to support this view.
From Parbery-Clark et al.:
Musicians have lifelong experience parsing melodies from background harmonies, which can be considered a process analogous to speech perception in noise. To investigate the effect of musical experience on the neural representation of speech-in-noise, we compared subcortical neurophysiological responses to speech in quiet and noise in a group of highly trained musicians and nonmusician controls. Musicians were found to have a more robust subcortical representation of the acoustic stimulus in the presence of noise. Specifically, musicians demonstrated faster neural timing, enhanced representation of speech harmonics, and less degraded response morphology in noise. Neural measures were associated with better behavioral performance on the Hearing in Noise Test (HINT) for which musicians outperformed the nonmusician controls. These findings suggest that musical experience limits the negative effects of competing background noise, thereby providing the first biological evidence for musicians' perceptual advantage for speech-in-noise.
Monday, November 23, 2009
I liked this column by Thomas Friedman. Some clips:
...I’m not ready to cede the 21st century to China just yet...there are still two really important things that can’t be commoditized. Fortunately, America still has one of them: imagination...Who would cede a century in which imagination will have such a high value to an authoritarian society that controls its Internet and jails political prisoners?
But while our culture of imagination is still vibrant, the other critical factor that still differentiates countries today — and is not a commodity — is good governance, which can harness creativity. And that we may be losing. Why? Because at least six things have come together to fracture our public space and paralyze our ability to forge optimal solutions:
1) Money in politics has become so pervasive that lawmakers have to spend most of their time raising it, selling their souls to those who have it or defending themselves from the smallest interest groups with deep pockets that can trump the national interest.
2) The gerrymandering of political districts means politicians of each party can now choose their own voters and never have to appeal to the center.
3) The cable TV culture encourages shouting and segregating people into their own political echo chambers.
4) A permanent presidential campaign leaves little time for governing.
5) The Internet, which, at its best, provides a check on elites and establishments and opens the way for new voices and, which, at its worst provides a home for every extreme view and spawns digital lynch mobs from across the political spectrum that attack anyone who departs from their specific orthodoxy.
6) A U.S. business community that has become so globalized that it only comes to Washington to lobby for its own narrow interests; it rarely speaks out anymore in defense of national issues like health care, education and open markets.
And, while I'm passing on interesting New York Times pieces, this one on economic recovery viewed as self fulfilling prophecy.
Some work from van Veen et al. on attitude changes induced by cognitive dissonance:
When our actions conflict with our prior attitudes, we often change our attitudes to be more consistent with our actions. This phenomenon, known as cognitive dissonance, is considered to be one of the most influential theories in psychology. However, the neural basis of this phenomenon is unknown. Using a Solomon four-group design, we scanned participants with functional MRI while they argued that the uncomfortable scanner environment was nevertheless a pleasant experience. We found that cognitive dissonance engaged the dorsal anterior cingulate cortex and anterior insula; furthermore, we found that the activation of these regions tightly predicted participants' subsequent attitude change. These effects were not observed in a control group. Our findings elucidate the neural representation of cognitive dissonance, and support the role of the anterior cingulate cortex in detecting cognitive conflict and the neural prediction of attitude change.
Luders et al. examine brain differences not dependent on size in gray matter distributions between men and women. They find a number of regions where matched women had significantly larger gray matter (GM) volumes than in matched men, suggesting that anatomical differences between male and female brains exist independently of brain size effects. While they did not detect any regions of larger GM volume in men than in women, there were a number of regions indicating larger GM volumes in women than in men. Comparing men and women with identical brain sizes, they detected the largest clusters in the right and left caudate extending into adjacent regions of the basal ganglia, as well as into the left orbitofrontal region. These findings appear to disagree with previous findings indicating that brain volume (rather than sex) is the main variable accounting for differences in gray matter proportion. Their abstract:
The different brain anatomy of men and women is both a classic and continuing topic of major interest. Among the most replicated and robust sex differences are larger overall brain dimensions in men, and relative increases of global and regional gray matter (GM) in women. However, the question remains whether sex-typical differences in brain size (i.e., larger male and smaller female brains) or biological sex itself account for the observed sex effects on tissue amount and distribution. Exploring cerebral structures in men and women with similar brain size may clarify the true contribution of biological sex. We thus examined a sample of 24 male and 24 female subjects with brains identical in size, in addition to 24 male and 24 female subjects with considerable brain size differences. Using this large set of brains (n = 96), we applied a well validated and automated voxel-based approach to examine regional volumes of GM. While we revealed significant main effects of sex, there were no significant effects of brain size (and no significant interactions between sex and brain size). When conducting post hoc tests, we revealed a number of regions where women had larger GM volumes than men. Importantly, these sex effects remained evident when comparing men and women with the same brain size. Altogether, our findings suggest that the observed increased regional GM volumes in female brains constitute sex-dependent redistributions of tissue volume, rather than individual adjustments attributable to brain size.
Friday, November 20, 2009
Many broad claims about human behavior are based on experiments done samples drawn from western, educated, industrialized, rich, and democratic societies (i.e. WEIRD - the subjects of psychological experiments are mainly U.S. college undergraduates!). Henrich et al. argue in a Brain and Behavioral Sciences preprint (PDF here) that WEIRD subjects are particularly unusual compared with the rest of our species - frequent outliers. Here is their abstract:
Behavioral scientists routinely publish broad claims about human psychology and behavior in the world’s top journals based on samples drawn entirely from Western, Educated, Industrialized, Rich and Democratic (WEIRD) societies. Researchers—often implicitly—assume that either there is little variation across human populations, or that these “standard subjects” are as representative of the species as any other population. Are these assumptions justified? Here, our review of the comparative database from across the behavioral sciences suggests both that there is substantial variability in experimental results across populations and that WEIRD subjects are particularly unusual compared with the rest of the species—frequent outliers. The domains reviewed include visual perception, fairness, cooperation, spatial reasoning, categorization and inferential induction, moral reasoning, reasoning styles, self-concepts and related motivations, and the heritability of IQ. The findings suggest that members of WEIRD societies, including young children, are among the least representative populations one could find for generalizing about humans. Many of these findings involve domains that are associated with fundamental aspects of psychology, motivation, and behavior—hence, there are no obvious a priori grounds for claiming that a particular behavioral phenomenon is universal based on sampling from a single subpopulation. Overall, these empirical patterns suggests that we need to be less cavalier in addressing questions of human nature on the basis of data drawn from this particularly thin, and rather unusual, slice of humanity. We close by proposing ways to structurally re-organize the behavioral sciences to best tackle these challenges.
I had been unaware that our vigilance during a sustained attention task varies in a systematic way. Aue et al. have examined suggested rhythmic oscillations in the vigilance with which we maintain sustained attention by developing some continuous performance tasks:
...The current series of investigations sought to manipulate suggested periodicities of 1.5 and 5.2 min by altering task difficulty: tracking a white dot moving in a random pattern across an otherwise black computer display , administering caffeine, and testing on an ecologically valid task (simulated driving). Strong evidence of a 1.5 min periodicity was found across studies. Most participants did not demonstrate a 5.2 min periodicity. Moreover, the 1.5 min periodicity was resistant to task manipulations and appeared in similar levels across conditions in all experiments. These rhythms may be indicative of an endogenous system that modulates sustained attention in humans.
Thursday, November 19, 2009
Here is a curious fragment... Brinkworth et al. studied 106 obese people put on either a low fat or low carbohydrate diet for a year, doing psychological assessment tests during this period. Initially, shedding pounds put both groups in a better mood. But, in the low carbohydrate group this effect began to wear off after the first few weeks. Over 1 year, there was a favorable effect of an energy-restricted low fat diet compared with an isocaloric low carbohydrate diet on mood state and affect in overweight individuals, but both diets had similar effects on working memory and speed of information processing.
Van Der Werf et al. investigate whether motor skill enhancement through prior observation requires sleep to follow the observation to consolidate the procedural memory:
Numerous studies have shown that sleep enhances memory for motor skills learned through practice. Motor skills can, however, also be learned through observation, a process possibly involving the mirror neuron system. We investigated whether motor skill enhancement through prior observation requires sleep to follow the observation, either immediately or after a delay, to consolidate the procedural memory. Sequence-specific fingertapping performance was tested in 64 healthy subjects in a balanced design. Electromyography verified absence of overt or subliminal hand muscle activations during observation. The results show that immediate sleep is necessary for the enhancement of a motor skill through prior observation. Immediate sleep improved the speed of subsequent performance by 22 ± 11% (mean ± SEM) (P = 0.04) and reduced the error rate by 42 ± 19% (P = 0.02). In contrast, no performance gains occurred if sleep was initiated more than 12 h after observation. A second study on 64 subjects ruled out explicit familiarity with the sequence or the spatiotemporal rhythm of the sequence to underlie performance improvements. The sleep-dependent observational motor learning enhancement is at least similar to that previously reported for implicit and declarative memory. The apparent prerequisite of observing real movements indicates that subjects transfer experience obtained through observation of movements to subsequent self-initiated movements, in the absence of practice. Moreover, the consolidation of this transfer requires an early sleep window. These findings could improve learning new motor skills in athletes and children, but also in patients having to remaster skills following stroke or injury.
Wednesday, November 18, 2009
It turns out that genetic makeup would determine how vididly Proust's narrator, on biting into a madeleine cake dipped in tea, would experience his emotional memories. Work by Rasch et al. suggests that individual differences in the ADRA2B gene that codes the α2B adrenoreceptor, which plays an important role in vasoconstriction and blood pressure regulation, is also related to brain activation patterns underlying heightened emotional recall:
Emotionally arousing events are typically well remembered, but there is a large interindividual variability for this phenomenon. We have recently shown that a functional deletion variant of ADRA2B, the gene encoding the α2b-adrenergic receptor, is related to enhanced emotional memory in healthy humans and enhanced traumatic memory in war victims. Here, we investigated the neural mechanisms of this effect in healthy participants by using fMRI. Carriers of the ADRA2B deletion variant exhibited increased activation of the amygdala during encoding of photographs with negative emotional valence compared with noncarriers of the deletion. Additionally, functional connectivity between amygdala and insula was significantly stronger in deletion carriers. The present findings indicate that the ADRA2B deletion variant is related to increased responsivity and connectivity of brain regions implicated in emotional memory.
Articles on a particular topic seem to come out in clusters. Shortly after doing yesterday's post on the origin of religions I see this article by Nicholas Wade in the NYTimes. He makes some further interesting points.
For atheists, it is not a particularly welcome thought that religion evolved because it conferred essential benefits on early human societies and their successors. If religion is a lifebelt, it is hard to portray it as useless...For believers, it may seem threatening to think that the mind has been shaped to believe in gods, since the actual existence of the divine may then seem less likely.
It is easier to see from hunter-gatherer societies how religion may have conferred compelling advantages in the struggle for survival. Their rituals emphasize not theology but intense communal dancing that may last through the night. The sustained rhythmic movement induces strong feelings of exaltation and emotional commitment to the group. Rituals also resolve quarrels and patch up the social fabric.
The ancestral human population of 50,000 years ago, to judge from living hunter-gatherers, would have lived in small, egalitarian groups without chiefs or headmen. Religion served them as an invisible government. It bound people together, committing them to put their community’s needs ahead of their own self-interest. For fear of divine punishment, people followed rules of self-restraint toward members of the community. Religion also emboldened them to give their lives in battle against outsiders. Groups fortified by religious belief would have prevailed over those that lacked it, and genes that prompted the mind toward ritual would eventually have become universal.
Could the evolutionary perspective on religion become the basis for some kind of detente between religion and science? Biologists and many atheists have a lot of respect for evolution and its workings, and if they regarded religious behavior as an evolved instinct they might see religion more favorably, or at least recognize its constructive roles. Religion is often blamed for its spectacular excesses, whether in promoting persecution or warfare, but gets less credit for its staple function of patching up the moral fabric of society. But perhaps it doesn’t deserve either blame or credit. If religion is seen as a means of generating social cohesion, it is a society and its leaders that put that cohesion to good or bad ends.
Tuesday, November 17, 2009
Elizabeth Culotta writes the 11th essay in Science's series in honor of the Year of Darwin, which explores the human propensity to believe in unseen deities. She describes a new field:'the cognitive science of religion', which draws on psychology, anthropology, and neuroscience to understand the mental building blocks of religious thought. Here are a few slightly edited clips from the essay:
...there remains a yawning gap between the material evidence of the archaeological record and the theoretical models of psychologists. Archaeological objects fall short of revealing our ancestors' minds while on the psychological side more evidence is needed.
...Many researchers take the use of symbols as a clue to budding spirituality. As far back as 100,000 years ago, people at the South African site of Blombos Cave incised pieces of ochre with geometric designs, creating the first widely recognized signs of symbolic behavior.
...While archaeologists trace the outward expressions of religious and symbolic behavior, another group of researchers is trying to trace more subtle building blocks of religious belief, seeking religion's roots in our minds.
...According to the emerging cognitive model of religion, we are so keenly attuned to the designs and desires of other people that we are hypersensitive to signs of "agents": thinking minds like our own... a "hypertrophy of social cognition" leads us to attribute random events or natural phenomena to the agency of another being.
...young children prefer "teleological," or purpose-driven, explanations rather than mechanical ones for natural phenomena...in several studies British and American children in first, second, and fourth grades were asked whether rocks are pointy because they are composed of small bits of material or in order to keep animals from sitting on them. The children preferred the teleological explanation. They give an animistic quality to the rock; it's protecting itself...we all from childhood have a bias to see the natural world as purposefully designed. It's a small step to suppose that the design has a designer.
...a hair-trigger agency detector could work with another sophisticated element of the human mind to make us prone to believe in gods: what's called theory of mind, or the understanding that another being has a mind with intentions, desires, and beliefs of its own.
...If you suspect that an agent was responsible for some mysterious event, it's a short step to thinking that the agent has a mind like your own. Higher order theory of mind enables you to represent mental states of beings not immediately or visibly present, and who could have a very different perspective than your own. That's what you need to have a rich representation of what it might be like to be a god. (It's also what is needed to have a functional religion, because people need to know that others share their beliefs.) As Darwin put it, humans developing religion "would naturally attribute to spirits the same passions, the same love of vengeance, or simplest form of justice, and the same affections which they themselves feel."
...Some fMRI studies lend support to this idea. When subjects in an fMRI scanner are asked to evaluate statements about God's emotions and relationships to humans, such as, "God is removed from the world" and "God is forgiving," the areas that light up, such as the inferior frontal gyrus on both sides of the brain, are also involved in theory of mind. This and other results argue against any special "god region" of the brain as some have suggested; rather, religious belief might co-opt widely distributed brain sectors, including many concerned with so-called theory of mind.
Many favor an additional class of explanations for why religion is so prominent in every culture: It promotes cooperative behavior among strangers and so creates stable groups. The hypothesis is that religion is actually adaptive: By encouraging helpful behavior, religious groups boost the biological survival and reproduction of their members. Adhering to strict behavioral rules may signal that a religion's members are strongly committed to the group and so will not seek a free ride, a perennial problem in cooperative groups
Fast and Chen note that a startling 37% of American workers—roughly 54 million people—have been bullied at work, primarily having been sabotaged, yelled at, or belittled by their bosses . This statistic resonates with research showing a link between social power and aggression (i.e., acts aimed at harming other individuals, physically or otherwise). However, it also indicates that the link between power and aggression is not universal—after all, 63% of American workers have not been bullied at work. These observations raise an intriguing pair of questions: When are power holders most likely to behave aggressively, and why do they do so? Their abstract (PDF here):
When and why do power holders seek to harm other people? The present research examined the idea that aggression among the powerful is often the result of a threatened ego. Four studies demonstrated that individuals with power become aggressive when they feel incompetent in the domain of power. Regardless of whether power was measured in the workplace, manipulated via role recall, or assigned in the laboratory, it was associated with heightened aggression when paired with a lack of self-perceived competence. As hypothesized, this aggression appeared to be driven by ego threat: Aggressiveness was eliminated among participants whose sense of self-worth was boosted. Taken together, these findings suggest that (a) power paired with self-perceived incompetence leads to aggression, and (b) this aggressive response is driven by feelings of ego defensiveness. Implications for research on power, competence, and aggression are discussed.
Monday, November 16, 2009
Broom et al. observe that domestic pigs can quickly learn how mirrors work and will use their understanding of reflected images to scope out their surroundings and find their food. Angier reviews this work and notes that:
Other researchers have found that pigs are brilliant at remembering where food stores are cached and how big each stash is relative to the rest. They’ve shown that Pig A can almost instantly learn to follow Pig B when the second pig shows signs of knowing where good food is stored, and that Pig B will try to deceive the pursuing pig and throw it off the trail so that Pig B can hog its food in peace.One researcher looks
... at the pig as a great animal model for human lifestyle diseases...Pigs like to lie around, they like to drink if given the chance, they’ll smoke and watch TV.
Benedict Carey reviews the latest dream model suggested by Alan Hobson, whose work has stressed the more biological aspects of dreams and downplayed the idea that dreams have great psychological, psychoanalytic or Jungian archetypal significance. In general his models have suggested dreams to be confabulations generated in response to bottom up signals from the limbic system getting some regenerative exercise. His latest model suggests that REM sleep may constitute a protoconscious state, providing a virtual reality model of the world that is of functional use to the development and maintenance of waking consciousness. The main function of rapid-eye-movement sleep, or REM, when most dreaming occurs, is physiological. The brain is warming its circuits, anticipating the sights and sounds and emotions of waking.
Part of the reason the diagnostic manual can move the boundaries and add or remove “mental disorders” so easily is that it focuses on surface appearances or behavior (symptoms) and is silent about causes. Symptoms can be arranged into groups in many ways, and there is no single right way to cluster them. Psychiatry is not at the stage of other branches of medicine, where a diagnostic category depends on a known biological mechanism. An example of where this does occur is Down syndrome, where surface appearances are irrelevant. Instead the cause — an extra copy of Chromosome 21 — is the sole determinant to obtain a diagnosis. Psychiatry, in contrast, does not yet have any diagnostic blood tests with which to reveal a biological mechanism.
..science hasn’t had a proper chance to test if there is a biological difference between Asperger syndrome and classic autism. My colleagues and I recently published the first candidate gene study of Asperger syndrome, which identified 14 genes associated with the condition.
We don’t yet know if Asperger syndrome is genetically identical or distinct from classic autism, but surely it makes scientific sense to wait until these two subgroups have been thoroughly tested before lumping them together in the diagnostic manual. I am the first to agree with the concept of an autistic spectrum, but there may be important differences between subgroups that the psychiatric association should not blur too hastily.
Friday, November 13, 2009
Ochsner et al use MRI to examine what is now becoming a common distinction, to consider the extent to which emotions arise via low-level processes that provide quick, bottom-up affective analyses of stimuli, versus high-level, top-down cognitive appraisal processes that draw upon stored knowledge. They did this by examining responses in trials with normatively aversive images (bottom-up trials) and also in novel trials in which participants cognitively interpreted neutral images as aversive (top-down trials). Here is the abstract, followed by a summary figure.
Emotions are generally thought to arise through the interaction of bottom-up and top-down processes. However, prior work has not delineated their relative contributions. In a sample of 20 females, we used functional magnetic resonance imaging to compare the neural correlates of negative emotions generated by the bottom-up perception of aversive images and by the top-down interpretation of neutral images as aversive. We found that (a) both types of responses activated the amygdala, although bottom-up responses did so more strongly; (b) bottom-up responses activated systems for attending to and encoding perceptual and affective stimulus properties, whereas top-down responses activated prefrontal regions that represent high-level cognitive interpretations; and (c) self-reported affect correlated with activity in the amygdala during bottom-up responding and with activity in the medial prefrontal cortex during top-down responding. These findings provide a neural foundation for emotion theories that posit multiple kinds of appraisal processes and help to clarify mechanisms underlying clinically relevant forms of emotion dysregulation.
Master et al. make the not very suprising yet interesting observation that the known pain-attenuating effects of social support can be observed by merely activating the mental representation of a supportive other. Simply viewing a loved one's picture can have pain-attenuating effects, a finding which fits with social psychological research showing that being primed with a social construct is enough to activate associated mental representations and to bias behavior. Simple reminders of loved ones, apart from actual supportive social interactions, appear to be sufficient to engender feelings of support.
Thursday, November 12, 2009
A fascinating compilation by Nickalls:
NOTE BOOK OF 1837
Astronomers might formerly have said that God foreordered each planet to move in its particular destiny. In the same manner God orders each animal created with certain forms in certain countries; but how much more simple and sublime [a] power—let attraction act according to certain law, such are inevitable consequences—let animals be created, then by the fixed laws of generation, such will be their successors. (1)
SKETCH OF 1842
There is a simple grandeur in the view of life with powers of growth, assimilation and reproduction, being originally breathed into matter under one or a few forms, and that whilst this our planet has gone circling on according to fixed laws, and land and water, in a cycle of change, have gone on replacing each other, that from so simple an origin, through the process of gradual selection of infinitesimal changes, endless forms most beautiful and most wonderful have been evolved. (2)
ESSAY OF 1844
There is a simple grandeur in this view of life with its several powers of growth, reproduction and of sensation, having been originally breathed into matter under a few forms, perhaps into only one, and that whilst this planet has gone cycling onwards according to the fixed laws of gravity and whilst land and water have gone on replacing each other—that from so simple an origin, through the selection of infinitesimal varieties, endless forms most beautiful and most wonderful have been evolved. (2)
ON THE ORIGIN OF SPECIES, 1859
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved. (3)
Here is some fascinating work from Carreiras et al. showing brain changes in adult Colombian guerrillas re-integrating into mainstream society and learning to read for the first time as adults:
Language is a uniquely human ability that evolved at some point in the roughly 6,000,000 years since human and chimpanzee lines diverged. Even in the most linguistically impoverished environments, children naturally develop sophisticated language systems. In contrast, reading is a learnt skill that does not develop without intensive tuition and practice. Learning to read is likely to involve ontogenic structural brain changes, but these are nearly impossible to isolate in children owing to concurrent biological, environmental and social maturational changes. In Colombia, guerrillas are re-integrating into mainstream society and learning to read for the first time as adults. This presents a unique opportunity to investigate how literacy changes the brain, without the maturational complications present in children. Here we compare structural brain scans from those who learnt to read as adults (late-literates) with those from a carefully matched set of illiterates. Late-literates had more white matter in the splenium of the corpus callosum and more grey matter in bilateral angular, dorsal occipital, middle temporal, left supramarginal and superior temporal gyri. The importance of these brain regions for skilled reading was investigated in early literates, who learnt to read as children. We found anatomical connections linking the left and right angular and dorsal occipital gyri through the area of the corpus callosum where white matter was higher in late-literates than in illiterates; that reading, relative to object naming, increased the interhemispheric functional connectivity between the left and right angular gyri; and that activation in the left angular gyrus exerts top-down modulation on information flow from the left dorsal occipital gyrus to the left supramarginal gyrus. These findings demonstrate how the regions identified in late-literates interact during reading, relative to object naming, in early literates.
Wednesday, November 11, 2009
I can't resist passing on this item in ScienceNow:
Oral sex is surprisingly rare in the animal kingdom. Humans do it, of course. As do bonobos, our close relatives. But now researchers have observed the practice for the first time in a non-primate. Libiao Zhang, a biologist at Guangdong Entomological Institute in Guangzhou, China, and colleagues had been studying the mating behavior of the short-nosed fruit bat (Cynopterus sphinx), which is native to southeast Asia....Of the 20 observed mating bat pairs, 70% of the females performed fellatio on the males, the team reports online this week in PLoS ONE. The males never withdrew while being licked, and the authors found that the longer a female licked, the longer copulation lasted (for each second of licking, the female bats gained 6 seconds of copulation). The team speculates that licking helps maintain the male's erection, and that the saliva increases lubrication, both of which may prolong intercourse. In all, fellating females mated for an average of 4 minutes, twice as long as the other females.
From Finkel and Eastwick:
Men tend to be less selective than women when evaluating and pursuing potential romantic partners. The present experiment employed speed-dating procedures to test a novel explanation for this sex difference: The mere act of physically approaching a potential romantic partner (vs. being approached), a behavior that is more characteristic of men than of women, increases one's attraction to that partner. This hypothesis was supported in a sample of speed daters (N= 350) who attended a heterosexual event where either men (eight events) or women (seven events) rotated from one partner to the next while members of the other sex remained seated. Rotators were significantly less selective than were sitters, which meant that the tendency for men to be less selective than women at events where men rotated disappeared at events where women rotated. These effects were mediated by increased self-confidence among rotators relative to sitters.
Tuesday, November 10, 2009
Janet Maslin offers a review of an interesting new book by Michael Specter: DENIALISM -How Irrational Thinking Hinders Scientific Progress, Harms the Planet and Threatens Our Lives. He explores the ways in which scientific information is misunderstood by a sizeable portion of the populace, struggling with change, that deflects reality to bask in more comfortable illusion. Here are a few clips:
In “The Organic Fetish,” a chapter that ably illustrates this book’s tactics and purpose, he uses Whole Foods as the apotheosis of a strain of magical thinking. First of all, he asks, what exactly is organic food? Is it more healthful than genetically engineered food or than food that has been harvested by robot-guided machinery rather than human hands? And are organic fertilizers more earth-friendly than synthetic ones? “There are no short answers to those questions (at least none that are true),” he says...And whatever the merits of organic farming for societies that can afford it, what happens in places where food, land or water are scarce? There is a case to be made for agricultural methods that make the most efficient use of new technologies, and thus for genetically engineered crops that produce increased yields. But these are widely derided as Frankenfoods. Their ability to scare people and trigger blanket resistance is one of this book’s foremost illustrations of denialism in action.
Of all the grenades lobbed by “Denialism,” the most explosive is aimed at Dr. Weil, the otherwise-sacrosanct avatar of New Age medicine. In the chapter called “The Era of Echinacea” Mr. Specter describes signing up for one of Dr. Weil’s customized mail-order regimens. “Dr. Weil, who argues that we need to reject the prevailing impersonal approach, reached out from cyberspace to recommend each of these pills wholeheartedly and specifically, just for me,” But Mr. Specter decided that the pills advocated by Dr. Weil fell into three categories: those that did no particular good, those that did some good but could interfere with the effects of prescribed medicines, and those that “seemed just plain dangerous.”..What bothered him more than Dr. Weil’s advice was Dr. Weil’s philosophy. “The idea that accruing data is simply one way to think about science has become a governing tenet of the alternative belief system,” Mr. Specter writes. And the additional idea that the evidence of experience is as important as the results of meticulous scientific testing is, in Mr. Specter’s view, one of the most dangerous forms of denialism, especially when it comes from a figure of Dr. Weil’s stature. As “Denialism” puts it: “It is much easier to dismiss a complete kook — there are thousands to choose from — than a respected physician who, interspersed with disquisitions about life forces and energy fields, occasionally has something useful to say.”
Bidelman and Krishnan make interesting observations suggesting that very fundamental low level sensory processing at the level of the brain stem may determine what sound intervals we find consonant or dissonant:
Consonant and dissonant pitch relationships in music provide the foundation of melody and harmony, the building blocks of Western tonal music. We hypothesized that phase-locked neural activity within the brainstem may preserve information relevant to these important perceptual attributes of music. To this end, we measured brainstem frequency-following responses (FFRs) from nonmusicians in response to the dichotic presentation of nine musical intervals that varied in their degree of consonance and dissonance. Neural pitch salience was computed for each response using temporally based autocorrelation and harmonic pitch sieve analyses. Brainstem responses to consonant intervals were more robust and yielded stronger pitch salience than those to dissonant intervals. In addition, the ordering of neural pitch salience across musical intervals followed the hierarchical arrangement of pitch stipulated by Western music theory. Finally, pitch salience derived from neural data showed high correspondence with behavioral consonance judgments (r = 0.81). These results suggest that brainstem neural mechanisms mediating pitch processing show preferential encoding of consonant musical relationships and, furthermore, preserve the hierarchical pitch relationships found in music, even for individuals without formal musical training. We infer that the basic pitch relationships governing music may be rooted in low-level sensory processing and that an encoding scheme that favors consonant pitch relationships may be one reason why such intervals are preferred behaviorally.
Monday, November 09, 2009
Starting to read this piece by Miller and Stone at first left me speechless with incredulity. This would appear to be the perfect scam (or business model) - getting people to pay real money for a product that doesn't exist. We're talking about virtual goods with a marginal cost of zero and a profit margin of 100%. The virtual goods are things like swords and spells in virtual fantasy realms, or...
In Restaurant City, a game by Playfish on Facebook, 18 million active users manage their own cafe and stock it with virtual casseroles and cakes. In Zynga’s game FarmVille, 62 million agrarian dreamers cultivate a farm, plant squash seeds and harvest their crops with tractors. (the figure shows a consumer with her cat, Demon Baby, bought for the game Pet Society.)Crazy? Maybe not:
...strong — and somewhat rational — motives are at work. Users of social networks can buy one another gifts, like images of flowers and birthday cakes, typically for a dollar each. Facebook recently expanded its gift store to allow other companies to list their virtual wares, like greeting cards...“It’s not about the good itself, it’s about the underlying human emotion or desire,” said Moshe Koyfman, a principal at Spark Capital, which has invested in two virtual-goods start-ups. “The recipient knows the person took time, picked something meaningful and spent money on it.”Maybe we should view this as the ultimate "Green" consumer product - money spent with zero environmental impact (if you accept that the energy sucking infrastructure of the internet would be there anyway).
Some game fans claim that in some cases, virtual goods can be better than the real thing. Jamie Kwong, a 13-year-old in Altadena, Calif., spends hours a week on a “paper doll” site called Stardoll, buying dresses and handbags. She created Juillet606, with brown eyes and hair to match her own. Unlike the actual paper dolls she used to play with, the tabs do not rip off....“With Stardoll it all stays on there, my brother can’t get on it, and everything is good,” she said.
Krugel et al show that a genetic change that leads to replacement of the amino acid valine with methionine in an enzyme regulating brain dopamine levels alters the flexible adaptation of reward based learning.
We show a behavioral advantage for the phylogenetically ancestral Val/Val genotype in an instrumental reversal learning task that requires rapid and flexible adaptation of decisions to changing reward contingencies in a dynamic environment...we discovered that a higher and more flexible learning rate underlies the advantage of the Val/Val genotype. Model-based fMRI analysis revealed that greater and more differentiated striatal fMRI responses to prediction errors reflect this advantage on the neurobiological level. Learning rate-dependent changes in effective connectivity between the striatum and prefrontal cortex were greater in the Val/Val than Met/Met genotype, suggesting that the advantage results from a downstream effect of the prefrontal cortex that is presumably mediated by differences in dopamine metabolism. These results show a critical role of dopamine in processing the weight a particular prediction error has on the expectation updating for the next decision.
Friday, November 06, 2009
Synthetic agents such as androids or computer-animated characters can elicit responses from us (mainly of positive emotional valence) similar to those elicited by real humans as long as they have a low resemblance to humans. But, if these agents become too realistic, we find them unsettling. This feeling of eeriness is known as the “uncanny valley” and is associated with entities that elicit the concept of a human, but do meet all of the requirements for being one. Steckenfinger and Ghazanfar find that monkeys apparently have the same kind of response.
Very realistic human-looking robots or computer avatars tend to elicit negative feelings in human observers. This phenomenon is known as the “uncanny valley” response. It is hypothesized that this uncanny feeling is because the realistic synthetic characters elicit the concept of “human,” but fail to live up to it. That is, this failure generates feelings of unease due to character traits falling outside the expected spectrum of everyday social experience. These unsettling emotions are thought to have an evolutionary origin, but tests of this hypothesis have not been forthcoming. To bridge this gap, we presented monkeys with unrealistic and realistic synthetic monkey faces, as well as real monkey faces, and measured whether they preferred looking at one type versus the others (using looking time as a measure of preference). To our surprise, monkey visual behavior fell into the uncanny valley: They looked longer at real faces and unrealistic synthetic faces than at realistic synthetic faces.
Palminteri et al. show that the expected values of two options, which were cued by visual symbols and chosen with either the left or right hand, enhanced activity, respectively, in the right or left (i.e. contralateral) ventral prefrontal cortex, thus respecting the topography of the brain systems elicited by the available options.
A main focus in economics is on binary choice situations, in which human agents have to choose between two alternative options. The classical view is that decision making consists of valuating each option, comparing the two expected values, and selecting the higher one. Some neural correlates of option values have been described in animals, but little is known about how they are represented in the human brain: are they integrated into a single center or distributed over different areas? To address this issue, we examined whether the expected values of two options, which were cued by visual symbols and chosen with either the left or right hand, could be distinguished using functional magnetic resonance imaging. The two options were linked to monetary rewards through probabilistic contingencies that subjects had to learn so as to maximize payoff. Learning curves were fitted with a standard computational model that updates, on a trial-by-trial basis, the value of the chosen option in proportion to a reward prediction error. Results show that during learning, left and right option values were specifically expressed in the contralateral ventral prefrontal cortex, regardless of the upcoming choice. We therefore suggest that expected values are represented in a distributed manner that respects the topography of the brain systems elicited by the available options.
Thursday, November 05, 2009
Just as I was thinking about doing a post on the recent paper by Wang et al. showing improved memory performance in rats genetically engineered to over-express a subunit of a synaptic receptor gene, my son-in-law J.T. Smith pointed out a very nice summary of the work in h+ magazine.
Our body image, as well as our body's location in space, can be manipulated by altering sensory feedback from the environment. Now Moseley and Brugger make the amazing observation that we can change our sense of ownership and agency to include impossible movements, independent of sensory feedback from the body or external feedback about task performance.
The feeling we have of our own body, sometimes called “body image,” is fundamental to self-awareness. However, by altering sensory input, the body image can be modified into impossible configurations. Can impossible movements of the body image be conjured solely via internally generated mechanisms, and, if so, do the structural characteristics of the body image modify to accommodate the new movements? We encouraged seven amputees with a vivid phantom arm to learn to perform a phantom wrist movement that defied normal anatomical constraints. Four reported success. Learning the impossible movement coincided in time with a profound change in the body image of the arm, including a sense of ownership and agency over a modified wrist joint. Remarkably, some previous movements and functional tasks involving the phantom arm became more difficult once the shift in body image had occurred. Crucially, these introspective reports were corroborated by robust empirical data from motor imagery tasks, about which amputees were naïve and to which assessors were blind. These results provide evidence that: a completely novel body image can be constructed solely by internally generated mechanisms; that the interdependence between movement repertoire and structural constraints of the body persists even when the structural constraints imparted by the body do not—the body image we construct still constrains imagined movements; and that motor learning does not necessarily need sensory feedback from the body or external feedback about task performance.
John Tierney does a nice piece on one sort of contemporary ethnography, in this case dealing with gossip as reputational warfare.
...this time enthnographers have returned from the field with footage of a truly savage native ritual: teachers at an elementary school in the Midwest dishing about their principal behind her back.
Wednesday, November 04, 2009
Two fascinating articles (Brooks, who points to Yang) on how how technology has so fundamentally changed the ways we seek both one time and long term partners. I've tried the Grindr iPhone App described below by Yang (its GPS feature doesn't work worth diddly... it told me a handsome guy was 2,000 ft. away, and after we began to set up a meeting, he turned out to be in Iowa!). It is clear, as noted by Brooks, that all this technology "seems to threaten the sort of recurring and stable reciprocity that is the building block of trust."
So there’s this iPhone app called Grindr. It’s a GPS-enabled social-networking service for gay men. It tells you how many feet away a possible hookup is standing. Each profile comes with a picture, a tagline, the relevant stats, and a declaration of interest. You scroll through a column of heads and torsos arranged in descending order of proximity, tapping on the ones that seem promising and chatting with the ones who want the same things you do. As you make your way through the city, the menu of men reshuffles, and the erotic terrain updates in real time.
Has the search for erotic gratification ever been so efficient? Until recently, being a cad or coquette took a lot of work: You needed to buy a little black book, and you had to go around filling it, and then you had to schedule your calls for a time when the target of your seduction was likely to be at home. The less-self-assured daters in New York faced the sickening anxiety of the first phone call, or the cold approach in the bar. There were palliatives designed to help people cope—the newspaper personal ads, the paid dating services, the dirty videos and magazines—but they were generally understood to be the province of weirdos and losers.
No more. The social technologies that assist in dating and mating today are more than palliatives—they’ve changed the nature of the game. If the cold approach is more than you can deal with, put up a Craigslist ad, or join OkCupid, Manhunt, or Nerve. If the phone call makes you nervous, send a text message. And while you’re at it, send a text message to a half-dozen other people with everyone’s favorite late-night endearment: “where u at?” If nothing works out and you find yourself alone at home again, simply fire up XTube or YouPorn and choose from an endless variety of positions to help you reach a late-night climax.
Claudia Wallis does an article on the proposal to drop the name "Asperger's syndrome,' folding it, along with the term "pervasive developmental disorder" into the term "Autism spectrum disorder." The simple fact appears to be that "nobody has been able to show consistent differences between what clinicians diagnose as Asperger’s syndrome and what they diagnose as mild autistic disorder." The not so minor problem is that the general population views "Asperger's syndrome" more positively than autism, and the term has developed its own brand identity. "The Asperger’s diagnosis is used by health insurers, researchers, state agencies and schools — not to mention people with the disorder, many of whom proudly call themselves Aspies." On the other hand Ari Ne’eman, 21 - an activist who founded the Autistic Self-Advocacy Network, a 15-chapter organization he has built while in college - notes “My identity is attached to being on the autism spectrum, not some superior Asperger’s identity. I think the consolidation to one category of autism spectrum diagnosis will lead to better services.”
Tuesday, November 03, 2009
Borgerhoff Mulder et al. show that wealth inequality in 21 historical and contemporary "small-scale societies" is determined by the intergenerational transmission of different types of assets. From the editor's summary:
Wealthy contemporary societies exhibit varying extents of economic inequality, with the Nordic countries being relatively egalitarian, whereas there is a much larger gap between top and bottom in the United States. Borgerhoff Mulder et al. build a bare-bones model describing the intergenerational transmission of three different types of wealth—based on social networks, land and livestock, and physical and cognitive capacity—in four types of small-scale societies in which livelihoods depended primarily on hunting, herding, farming, or horticulture. Parameter estimates from a large-scale analysis of historical and ethnographic data were added to the model to reveal that the four types of societies display distinctive patterns of wealth transmission and that these patterns are associated with different extents of inequality.Here is the article abstract:
Small-scale human societies range from foraging bands with a strong egalitarian ethos to more economically stratified agrarian and pastoral societies. We explain this variation in inequality using a dynamic model in which a population’s long-run steady-state level of inequality depends on the extent to which its most important forms of wealth are transmitted within families across generations. We estimate the degree of intergenerational transmission of three different types of wealth (material, embodied, and relational), as well as the extent of wealth inequality in 21 historical and contemporary populations. We show that intergenerational transmission of wealth and wealth inequality are substantial among pastoral and small-scale agricultural societies (on a par with or even exceeding the most unequal modern industrial economies) but are limited among horticultural and foraging peoples (equivalent to the most egalitarian of modern industrial populations). Differences in the technology by which a people derive their livelihood and in the institutions and norms making up the economic system jointly contribute to this pattern.
Kind of a techie point, but I thought it interesting... Sirotin et al. have measured both increases in blood oxygenation and blood volume in the brains of two macaques while they performed a visual task. They find that blood-volume change is a better signal to use in brain imaging because it seems to be more closely linked to neural activity, occurring even before changes in blood oxygenation.
An engaging article on dog intelligence in Sunday's New York Times. And on the subject of dog smarts, a new and engaging book: Darwin's Dogs: How Darwin's Pets Helped Form a World-Changing Theory of Evolution (Frances Lincoln: 2009), by Emma Townshend.
Monday, November 02, 2009
I arrived at MindBlog's winter home in the Wilton Manors section of Fort Lauderdale just in time for Halloween. The photos (the one on the left being "Bride of Frankenstein with bride's maids") are from the Halloween street festival "Wicked Manors" held on the main street Wilton Drive, which is lined by gay bars and restaurants.
Bell et al. think about whether human prosocial behaviors such as food sharing, taxation, and warfare - nearly completely absent in other vertebrates - are more plausibly explained as arising from to cultural or genetic selection during competition among large groups. They use the term "group-level selection" to refer to the scenario in which groups differ in the frequency of individuals who are willing to sacrifice their own labor, time, or safety in ways that promote the competitive ability of the residential group, so that over time groups with higher frequencies of such “altruists” may tend to replace groups with fewer. A key point is that:
Selection for culturally-prescribed altruists occurs through the same process as for genes: groups of altruists leave more daughter societies. However, one advantage that cultural variation has over genetic is that it does not require violent inter-group competition, nor group extinctions. If failed groups were incorporated routinely into successful ones, conformist transmission and other forms of resocialization of failed groups can lead to effective cultural selection on groups even though such a pattern will generate rates of migration that keep genetic FST (a measure of genetic differentiation between populations) very low between neighbors. Thus selection on culture can be powerful precisely when genetic selection at the group level is weakest.The meat of the article is formal calculation using the Price equation (don't ask...) that suggests much greater scope for cultural rather than genetic group-level selection in allowing altruism to arise.
Here is an interesting piece from Hains et al. on stress and the prefrontal cortex. They use a rat model and a restraint stress paradigm to show that a drug can inhibit the working memory impairment and degenerative architectural changes caused by the stress.
The prefrontal cortex regulates behavior, cognition, and emotion by using working memory. Prefrontal functions are impaired by stress exposure. Acute, stress-induced deficits arise from excessive protein kinase C (PKC) signaling, which diminishes prefrontal neuronal firing. Chronic stress additionally produces architectural changes, reducing dendritic complexity and spine density of cortico-cortical pyramidal neurons, thereby disrupting excitatory working memory networks. In vitro studies have found that sustained PKC activity leads to spine loss from hippocampal-cultured neurons, suggesting that PKC may contribute to spine loss during chronic stress exposure. The present study tested whether inhibition of PKC with chelerythrine before daily stress would protect prefrontal spines and working memory. We found that inhibition of PKC rescued working memory impairments and reversed distal apical dendritic spine loss in layer II/III pyramidal neurons of rat prelimbic cortex. Greater spine density predicted better cognitive performance, the first direct correlation between pyramidal cell structure and working memory abilities. These findings suggest that PKC inhibitors may be neuroprotective in disorders with dysregulated PKC signaling such as bipolar disorder, schizophrenia, post-traumatic stress disorder, and lead poisoning—conditions characterized by impoverished prefrontal structural and functional integrity.