The weirdest people in the world?

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.

Cyclic variations in our vigilance

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.

Low fat makes you happier?

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.

The sooner you can sleep, the better you learn.

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.

Neurogenetics of remembering emotions past

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.

Evolution of "the God gene"

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.

Cognitive science and the origin of religions

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

When the boss feels inadequate - power, incompetence, and aggression

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.

Pig smarts

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.

Dreams as brain tuneups

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.

Debate over the term Asperger's syndrome - continued

Autism expert Simon Baron-Cohen (cousin of the comic actor Sacha Baron-Cohen) weighs in on the debate that I mentioned in my 11/4/09 post over dropping the term Asperger's syndrome.

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.

How you feel - the brain's bottom up and top down pathways

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.

Partner photographs can reduce experimentally induced pain

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.

Evolution of the end of Origin of the Species

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)

References

• 1. F. Darwin, Ed., The Life and Letters of Charles Darwin (John Murray, London, 1887).
• 2. G. de Beer, Evolution by Natural Selection (Cambridge Univ. Press, Cambridge, 1958).
• 3. C. Darwin, On the Origin of Species by Natural Selection... (John Murray, London, 1859).

An anatomical signature for literacy

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.

A little fellatio goes a long way...

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.

Manipulating sex differences in romantic selectivity

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.

Denialism

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.”

Neural correlates of musical consonance and dissonance

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.

Can you believe...? The perfect product

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.”

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.

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).

Genes that influence our adaptability to changing rewards

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.

Like us, monkeys don't like computer faces that are 'too real'.

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.

Our left and right hemispheres can selectively track expected value

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.

Genetic enhancement of memory.

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.

We can generate a novel body image internally, without external feedback

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.

Social functions of gossip

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.

The modern dating game.

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.

Asperger's syndrome to become Autism spectrum disorder?

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.”

The dynamics of social inequality.

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.

The best way to measure brain signals...

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.

Dog smarts

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.

Wicked Manors....

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.

Prosociality in large human groups more likely due to culture than to genetics.

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 F_ST (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.

A drug that protects prefrontal cortex from stress.

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.

Extroverts and introverts

I couldn't resist passing this on from the I CAN HAS CHEEZ BURGER site:

The brain's anatomy of emotion induced by music.

From Tranel, Adolphs, and collaborators, a fascinating piece of work reported in the International Journal of Psychology (check out the other articles in this issue, which has the theme 'Central and peripheral nervous system interactions: From mind to brain to body' Here is the abstract from their paper, followed by one table:

Does feeling an emotion require changes in autonomic responses, as William James proposed? Can feelings and autonomic responses be dissociated? Findings from cognitive neuroscience have identified brain structures that subserve feelings and autonomic response, including those induced by emotional music. In the study reported here, we explored whether feelings and autonomic responses can be dissociated by using music, a stimulus that has a strong capacity to induce emotional experiences. We tested two brain regions predicted to be differentially involved in autonomic responsivity (the ventromedial prefrontal cortex) and feeling (the right somatosensory cortex). Patients with damage to the ventromedial prefrontal cortex were impaired in their ability to generate skin-conductance responses to music, but generated normal judgments of their subjective feelings in response to music. Conversely, patients with damage to the right somatosensory cortex were impaired in their self-rated feelings in response to music, but generated normal skin-conductance responses to music. Control tasks suggested that neither impairment was due to basic defects in hearing the music or in cognitively recognizing the intended emotion of the music. The findings provide evidence for a double dissociation between feeling emotions and autonomic responses to emotions, in response to music stimuli.

I thought the music clips they used to elicit emotional responses were interesting (click to enlarge):


By the way, here is another recent article by Salimpoor et al. on emotional arousal caused by music.

Dopamine, a molecule of motivation

Angier does a summary.

MindBlog on the road.

Over the past month of unseasonably cold weather here in Middleton Wisconsin my movement has become increasingly stiff and arthritic, so today I am loading up the car and driving with my two abyssinian cats to Fort Lauderdale for the winter, unable to predict the frequency of posts for the next few days. The picture shows a Maple tree in my front yard.

A jaded view....

A less positive view of humankind than the one described in the previous post - from the Oct. 26 issue of The New Yorker. The caption: "Well, that was a waste of time." :

Nature's lessons for a more kind society.

Blog reader Gary Olson has pointed me to his review of Franz De Waal's new book
"The Age of Empathy: Nature’s Lessons For A Kinder Society." From that review:

de Waal provides compelling support for the proposition that humans are “preprogrammed to reach out.” From dolphins ferrying injured companions to safety and grieving elephants, baboons and cats (yes, even cats) to commiserating mice and hydrophobic chimps risking death to save a drowning companion, this is a major contribution to understanding the biological genesis of our inborn capacity for empathy, hence morality.

In seven crisply written and wholly accessible chapters de Waal methodically demolishes the rationale behind Gordon Gekko’s admonition in the film "Wall Street" that greed “captures the essence of the evolutionary spirit.”...De Waal objects to an unrestrained market system, not capitalism itself. He prefers that the economic system be mitigated by more attention to empathy in order to soften its rough edges...Nevertheless, de Waal seriously underestimates certain capitalist imperatives and the role played by elites in cultivating callousness, thereby undermining social solidarity, reciprocity and empathy. Capitalist culture devalues an empathic disposition, and, as Erich Fromm argued some fifty years ago, there is a basic incompatibility between the underlying principles of capitalism and the lived expression of an ethos of empathy.

Learning sculpts our spontaneous resting brain activity.

Lewis et al. have demonstrated that learning an attention-demanding visual task modifies the spontaneous correlation of activity in the resting human brain - suggesting that the functional architecture of the brain is partly a product of previous experience. At left is a clay model representation of the human brain provided by Lewis, colored to indicate putative areas in frontal, temporal, and parietal cortex changed by a task. The abstract:

The brain is not a passive sensory-motor analyzer driven by environmental stimuli, but actively maintains ongoing representations that may be involved in the coding of expected sensory stimuli, prospective motor responses, and prior experience. Spontaneous cortical activity has been proposed to play an important part in maintaining these ongoing, internal representations, although its functional role is not well understood. One spontaneous signal being intensely investigated in the human brain is the interregional temporal correlation of the blood-oxygen level-dependent (BOLD) signal recorded at rest by functional MRI (functional connectivity-by-MRI, fcMRI, or BOLD connectivity). This signal is intrinsic and coherent within a number of distributed networks whose topography closely resembles that of functional networks recruited during tasks. While it is apparent that fcMRI networks reflect anatomical connectivity, it is less clear whether they have any dynamic functional importance. Here, we demonstrate that visual perceptual learning, an example of adult neural plasticity, modifies the resting covariance structure of spontaneous activity between networks engaged by the task. Specifically, after intense training on a shape-identification task constrained to one visual quadrant, resting BOLD functional connectivity and directed mutual interaction between trained visual cortex and frontal-parietal areas involved in the control of spatial attention were significantly modified. Critically, these changes correlated with the degree of perceptual learning. We conclude that functional connectivity serves a dynamic role in brain function, supporting the consolidation of previous experience.

Monkeys drumming - a gestural origin of speech and music?

From Remediosa, Logothetisa, and Kaysera:

Salient sounds such as those created by drumming can serve as means of nonvocal acoustic communication in addition to vocal sounds. Despite the ubiquity of drumming across human cultures, its origins and the brain regions specialized in processing such signals remain unexplored. Here, we report that an important animal model for vocal communication, the macaque monkey, also displays drumming behavior, and we exploit this finding to show that vocal and nonvocal communication sounds are represented by overlapping networks in the brain's temporal lobe. Observing social macaque groups, we found that these animals use artificial objects to produce salient periodic sounds, similar to acoustic gestures. Behavioral tests confirmed that these drumming sounds attract the attention of listening monkeys similarly as conspecific vocalizations. Furthermore, in a preferential looking experiment, drumming sounds influenced the way monkeys viewed their conspecifics, suggesting that drumming serves as a multimodal signal of social dominance. Finally, by using high-resolution functional imaging we identified those brain regions preferentially activated by drumming sounds or by vocalizations and found that the representations of both these communication sounds overlap in caudal auditory cortex and the amygdala. The similar behavioral responses to drumming and vocal sounds, and their shared neural representation, suggest a common origin of primate vocal and nonvocal communication systems and support the notion of a gestural origin of speech and music.


Characteristics of drumming sounds. (A) In this example, a macaque drums by firmly grasping the cage door with his forelimbs and shaking it vigorously and repeatedly. The inset displays the typical facial expression during drumming: open-mouth threatening, staring, forward directed pinnae. (B) Drumming sounds are acoustically distinct from typical vocalizations such as screams, grunts, or pant-threats. The repetitive beat pattern of the drumming sound produced by this action is visible in the time-frequency spectrum. The black line displays the power spectrum.

Meditation training can enhance the stability of our attention

Several groups collaborate to show that meditation training can can significantly affect attention and brain function.

The capacity to stabilize the content of attention over time varies among individuals, and its impairment is a hallmark of several mental illnesses. Impairments in sustained attention in patients with attention disorders have been associated with increased trial-to-trial variability in reaction time and event-related potential deficits during attention tasks. At present, it is unclear whether the ability to sustain attention and its underlying brain circuitry are transformable through training. Here, we show, with dichotic listening task performance and electroencephalography, that training attention, as cultivated by meditation, can improve the ability to sustain attention. Three months of intensive meditation training reduced variability in attentional processing of target tones, as indicated by both enhanced theta-band phase consistency of oscillatory neural responses over anterior brain areas and reduced reaction time variability. Furthermore, those individuals who showed the greatest increase in neural response consistency showed the largest decrease in behavioral response variability. Notably, we also observed reduced variability in neural processing, in particular in low-frequency bands, regardless of whether the deviant tone was attended or unattended. Focused attention meditation may thus affect both distracter and target processing, perhaps by enhancing entrainment of neuronal oscillations to sensory input rhythms, a mechanism important for controlling the content of attention. These novel findings highlight the mechanisms underlying focused attention meditation and support the notion that mental training can significantly affect attention and brain function.

Election night 2008: testosterone level of male McCain voters dropped

Stanton et al. collected saliva samples from 183 study participants before and after the results of the 2008 presidential election were announced. The results show that male Barack Obama voters (winners) had stable post-outcome testosterone levels, whereas testosterone levels dropped in male John McCain and Robert Barr (Libertarian candidate) voters (losers). There were no significant effects in female voters. These results were consistent with earlier studies showing testosterone decreases in male supporters of an athletic team after it loses a game.

Emotional contagion without conscious awareness

Tamietto et al. make the fascinating observation that unseen emotionally expressive facial or body movements (stimuli presented to the blind portion of the visual field of patients with damage to their visual cortex) cause arousal and facial reactions. They suggest that emotional contagion represents affective reactions mediated by visual pathways of old evolutionary origin that bypass cortical vision and allow emotion communication and affect sharing. Here is their abstract:

The spontaneous tendency to synchronize our facial expressions with those of others is often termed emotional contagion. It is unclear, however, whether emotional contagion depends on visual awareness of the eliciting stimulus and which processes underlie the unfolding of expressive reactions in the observer. It has been suggested either that emotional contagion is driven by motor imitation (i.e., mimicry), or that it is one observable aspect of the emotional state arising when we see the corresponding emotion in others. Emotional contagion reactions to different classes of consciously seen and “unseen” stimuli were compared by presenting pictures of facial or bodily expressions either to the intact or blind visual field of two patients with unilateral destruction of the visual cortex and ensuing phenomenal blindness. Facial reactions were recorded using electromyography, and arousal responses were measured with pupil dilatation. Passive exposure to unseen expressions evoked faster facial reactions and higher arousal compared with seen stimuli, therefore indicating that emotional contagion occurs also when the triggering stimulus cannot be consciously perceived because of cortical blindness. Furthermore, stimuli that are very different in their visual characteristics, such as facial and bodily gestures, induced highly similar expressive responses. This shows that the patients did not simply imitate the motor pattern observed in the stimuli, but resonated to their affective meaning. Emotional contagion thus represents an instance of truly affective reactions that may be mediated by visual pathways of old evolutionary origin bypassing cortical vision while still providing a cornerstone for emotion communication and affect sharing.

Health improves during economic depressions.

Having to live more lean and mean in economically hard times is apparently good for us. From Granados and Roux:

Recent events highlight the importance of examining the impact of economic downturns on population health. The Great Depression of the 1930s was the most important economic downturn in the U.S. in the twentieth century. We used historical life expectancy and mortality data to examine associations of economic growth with population health for the period 1920–1940. We conducted descriptive analyses of trends and examined associations between annual changes in health indicators and annual changes in economic activity using correlations and regression models. Population health did not decline and indeed generally improved during the 4 years of the Great Depression, 1930–1933, with mortality decreasing for almost all ages, and life expectancy increasing by several years in males, females, whites, and nonwhites. For most age groups, mortality tended to peak during years of strong economic expansion (such as 1923, 1926, 1929, and 1936–1937). In contrast, the recessions of 1921, 1930–1933, and 1938 coincided with declines in mortality and gains in life expectancy. The only exception was suicide mortality which increased during the Great Depression, but accounted for less than 2% of deaths. Correlation and regression analyses confirmed a significant negative effect of economic expansions on health gains. The evolution of population health during the years 1920–1940 confirms the counterintuitive hypothesis that, as in other historical periods and market economies, population health tends to evolve better during recessions than in expansions.

The nagging thing you don't understand about yourself

The 150th issue of the British Psychological Association's Research Digest email has posted a series of fascinating responses by leading psychologists to the request that they look inwards and share, in 150 words, one nagging thing they still don't understand about themselves.

The ages of mankind

Here is a neat graphic from the New York Times, apparently motivated by a paper this month in The Lancet saying that half of all the babies born in developed countries in 2007 will live to be 104. This suggests the addition of a 4th life stage, "Old old age" to current categories of youth, adulthood, and old age. The graphic depicts the stages of life as viewed in different historical eras by a variety of writers.

The 'society of selves' in each of us

David Brooks does a nice layman's summary titled "Where the Wild Things Are" of our modern views on how an individual's 'character' is composed - not from the top down by a single unifying feature, but rather from a pandora's box of possible selves, each of which can appear under a particular set of circumstances.

The Fat and Short of It

Engber writes a brief article on the fact that not only are there correlations between excess fat and health risk, but also shorter height correlates with increased coronary heart disease, diabetes or stroke. Also,

In the labor market, the effects of height and weight tend to run in parallel. A 2004 study by John Cawley of Cornell University found that severely obese white women who weigh more than two standard deviations above average — women who weigh, for example, more than 212 pounds if they’re 5 feet 4 inches tall — are paid up to 9 percent less for their work. Likewise, a decrease in a man’s height to the 25th percentile from the 75th — roughly to 5 feet 8 inches from 6 feet— is associated with, on average, a dip in earnings of 6 to 10 percent...And like obese people, short people are less likely to finish college than those of average weight. A paper from the July issue of the journal Economics and Human Biology used survey data from more than 450,000 adults to conclude that male college graduates are, on average, more than an inch taller than men who never finished high school.