Rewards work better than punishment in enhancing cooperation

Rand and colleagues have examined cooperation among 192 participants in a public goods game probing the fundamental tension between the interests of an individual and a group. In more than 50 rounds of interaction, each of four participants in a group would decide how much to contribute toward a common pool that benefited all four equally. Each participant was then able — at a cost to himself or herself — to either reward or punish each of the three other subjects for their contributions to the group, or lack thereof. Here is their abstract:

The public goods game is the classic laboratory paradigm for studying collective action problems. Each participant chooses how much to contribute to a common pool that returns benefits to all participants equally. The ideal outcome occurs if everybody contributes the maximum amount, but the self-interested strategy is not to contribute anything. Most previous studies have found punishment to be more effective than reward for maintaining cooperation in public goods games. The typical design of these studies, however, represses future consequences for today’s actions. In an experimental setting, we compare public goods games followed by punishment, reward, or both in the setting of truly repeated games, in which player identities persist from round to round. We show that reward is as effective as punishment for maintaining public cooperation and leads to higher total earnings. Moreover, when both options are available, reward leads to increased contributions and payoff, whereas punishment has no effect on contributions and leads to lower payoff. We conclude that reward outperforms punishment in repeated public goods games and that human cooperation in such repeated settings is best supported by positive interactions with others.

Friendship networks revealed by cell phone data.

Lazer and colleagues have compared data gathered through self-reporting versus data gathered through cell phone usage to determine whether such information can prove reliable in predicting friendships and job satisfaction. The study followed 94 subjects over the course of nine months.

Data collected from mobile phones have the potential to provide insight into the relational dynamics of individuals. This paper compares observational data from mobile phones with standard self-report survey data. We find that the information from these two data sources is overlapping but distinct. For example, self-reports of physical proximity deviate from mobile phone records depending on the recency and salience of the interactions. We also demonstrate that it is possible to accurately infer 95% of friendships based on the observational data alone, where friend dyads demonstrate distinctive temporal and spatial patterns in their physical proximity and calling patterns. These behavioral patterns, in turn, allow the prediction of individual-level outcomes such as job satisfaction.

Bad health is good business

Everyone should read this Michael Pollan article. Just two classic clips:

...food system reform has not figured in the national conversation about health care reform...the government is putting itself in the uncomfortable position of subsidizing both the costs of treating Type 2 diabetes and the consumption of high-fructose corn syrup.

There’s lots of money to be made selling fast food and then treating the diseases that fast food causes...As things stand, the health care industry finds it more profitable to treat chronic diseases than to prevent them. There’s more money in amputating the limbs of diabetics than in counseling them on diet and exercise.

This reminds me of the British Empire's 19th century Chinese tea for Indian opium scam that made opium addicts of the chinese.

At risk for pathological gambling.

I had not realized that treating Parkinson's disease or restless legs syndrome with dopamine agonists (mimics or enhancers) has been associated with impulse control disorders and pathological gambling. Abler et al. look at correlative changes in the brain:

We scanned 12 female restless leg syndrome patients without a history of pathological gambling. All patients were scanned twice: once whilst taking their regular medication with low dose dopamine receptor agonists and once after a washout phase interval. They performed an established gambling game task involving expectation and receipt or omission of monetary rewards at different levels of probabilities. Upon expectation of rewards, reliable ventral striatal activation was detected only when patients were on, but not when patients were off medication....Chronic dopamine receptor agonist medication changed the neural signalling of reward expectation predisposing the dopaminergic reward system to mediate an increased appetitive drive.

What if you were born with only one cerebral hemisphere?

Wolf Singer and collaborators have examined a woman whose right cerebral hemisphere did not develop after birth. Normally this hemisphere would receive information about the left visual field. From their abstract:

Despite the complete loss of her right hemisphere (di- and telencephalon) at birth, the patient's remaining hemisphere has not only developed maps of the contralateral (right) visual hemifield but, surprisingly, also maps of the ipsilateral (left) visual hemifield. Retinal ganglion-cells changed their predetermined crossing pattern in the optic chiasm and grew to the ipsilateral LGN. In the visual cortex, islands of ipsilateral visual field representations were located along the representations of the vertical meridian. In V1, smooth and continuous maps from contra- and ipsilateral hemifield overlap each other, whereas in ventral V2 and V3 ipsilateral quarter field representations invaded small distinct cortical patches. This reveals a surprising flexibility of the self-organizing developmental mechanisms responsible for map formation.

We are the ones we've been waiting for?

That messianic phrase from Obama's campaign turns out not to pan out very well, as illustrated particularly by the current health care debate. Anand Giridharadas notes that web participatory democracy has yielded some rather embarrassing results so far:

During the transition, the administration created an online “Citizen’s Briefing Book” for people to submit ideas to the president. “The best-rated ones will rise to the top, and after the Inauguration, we’ll print them out and gather them into a binder like the ones the president receives every day from experts and advisors,” Valerie Jarrett, a senior adviser to Mr. Obama, wrote to supporters...They received 44,000 proposals and 1.4 million votes for those proposals. The results were quietly published, but they were embarrassing — not so much to the administration as to us, the ones we’ve been waiting for...In the middle of two wars and an economic meltdown, the highest-ranking idea was to legalize marijuana, an idea nearly twice as popular as repealing the Bush tax cuts on the wealthy. Legalizing online poker topped the technology ideas, twice as popular as nationwide wi-fi. Revoking the Church of Scientology’s tax-exempt status garnered three times more votes than raising funding for childhood cancer.

Yet another theory on why we sleep

Among the functions of sleep suggested are memory consolidation and repair of neuronal wear and tear. Jerome Siegel offers a rationale for why the duration of sleep varies so much between animals. From Carey's reivew:

Why should lions get 15 hours a night and giraffes just 5 — when it is the giraffes who will be running for their lives come hunting time? How on earth do migrating birds, in flight for days on end, sleep? Why is it that some people are early birds as young adults and night owls when they’re older?

[Siegel]...argues that sleep evolved to optimize animals’ use of time, keeping them safe and hidden when the hunting, fishing or scavenging was scarce and perhaps risky. In that view, differences in sleep quality, up to and including periods of insomnia, need not be seen as problems but as adaptations to the demands of the environment...Consider the big brown bat, perhaps the longest-sleeping mammal of them all. It snoozes 20 hours a day, and spends the other 4 hunting mosquitoes and moths in the dusk and early evening. Increased waking time would seem to be highly maladaptive for this animal, since it would expend energy and be exposed to predatory birds with better vision and better flight abilities.

In humans, it is well known that sleep quality changes with age, from the long, deep plunges of early childhood to the much lighter, more frequently interrupted five or six hours that many elderly people call a night’s sleep...In Dr. Siegel’s view, it’s a matter of tradeoffs: older people no longer have a child’s need to grow, which requires deep, long sleep and may have more need and more ability to do things for themselves instead.

Why do we swear? For pain relief.

An interesting little nugget from Scientific American Mind.

Social contagion - Is happiness (or obesity) catching?

Clive Thompson does a nice article in this past Sunday's New York Times magazine on social contagion. It covers the Framingham study that I have mentioned in previous posts along with other studies that document how good as well as bad behaviors pass from friend to friend almost as if they were contagious viruses.

...behaviors may spread partly through the subconscious social signals that we pick up from those around us, which serve as cues to what is considered normal behavior. Scientists have been documenting this phenomenon; for example, experiments have shown that if a person is seated next to someone who’s eating more, he will eat more, too, unwittingly calibrating his sense of what constitutes a normal meal.

While emotional mirroring might be the most alluring idea about why behaviors spread, there are..

..two other possible explanations. One is “homophily,” the tendency of people to gravitate toward others who are like them. People who are gaining weight might well prefer to hang out with others who are also gaining weight, just as people who are happy might seek out others who are happy. The other possible explanation is that the shared environment — and not social contagion — might be causing the people of Framingham to change in groups. If a McDonald’s opens up in a Framingham neighborhood, it could cause a cluster of people living nearby to gain weight or become slightly happier (or sadder, depending on what they think about McDonald’s). The cluster of people would appear as though they are sharing a contagious form of behavior, but it would be an illusion.

How we change our decisions...

Resulaj et al develop a new model that accounts for how and when we change our mind after we make a decision. They do a series of experiments on subjects who were asked to move a handle to one of two positions dependent on a noisy visual stimulus. Analysis of the rare occasions where subjects changed their mind half way through selecting their answer shows that even after making a decision the brain continues to process the information it had gathered — information still in the processing pipeline— to either reverse or reaffirm its initial decision. Their new theory introduces the acts of vacillation and self correction into the decision-making process. The abstract outlines their basis idea:

A decision is a commitment to a proposition or plan of action based on evidence and the expected costs and benefits associated with the outcome. Progress in a variety of fields has led to a quantitative understanding of the mechanisms that evaluate evidence and reach a decision. Several formalisms propose that a representation of noisy evidence is evaluated against a criterion to produce a decision. Without additional evidence, however, these formalisms fail to explain why a decision-maker would change their mind. Here we extend a model, developed to account for both the timing and the accuracy of the initial decision, to explain subsequent changes of mind. Subjects made decisions about a noisy visual stimulus, which they indicated by moving a handle. Although they received no additional information after initiating their movement, their hand trajectories betrayed a change of mind in some trials. We propose that noisy evidence is accumulated over time until it reaches a criterion level, or bound, which determines the initial decision, and that the brain exploits information that is in the processing pipeline when the initial decision is made to subsequently either reverse or reaffirm the initial decision. The model explains both the frequency of changes of mind as well as their dependence on both task difficulty and whether the initial decision was accurate or erroneous. The theoretical and experimental findings advance the understanding of decision-making to the highly flexible and cognitive acts of vacillation and self-correction.

How chaos drives the brain.

I've been meaning to point out this excellent article in The New Scientist describing evidence that self-organised criticality is important brain function. It has links to a number of useful references.

Looming global disaster, anyone?

A panel of experts publishes a manifesto or guide in Science that is just the ticket for someone like myself who verges on clinical depression after every morning reading of the New York Times:

Energy, food, and water crises; climate disruption; declining fisheries; increasing ocean acidification; emerging diseases; and increasing antibiotic resistance are examples of serious, intertwined global-scale challenges spawned by the accelerating scale of human activity. They are outpacing the development of institutions to deal with them and their many interactive effects. The core of the problem is inducing cooperation in situations where individuals and nations will collectively gain if all cooperate, but each faces the temptation to take a free ride on the cooperation of others. The nation-state achieves cooperation by the exercise of sovereign power within its boundaries. The difficulty to date is that transnational institutions provide, at best, only partial solutions, and implementation of even these solutions can be undermined by internation competition and recalcitrance.


Figure - Interactive effects of global drivers on unwanted outcomes in the state of the world. Some outcomes also act as drivers of others (dashed arrows).

The major powers must be willing to enforce agreements, but legitimacy will depend on acceptance by numerous and diverse countries and by nongovernmental actors, such as civil society and business. This seems to be the basis for the greater success of the Montreal Protocol relative to the Kyoto Protocol. Strong backing by a majority for collective action, even though it may restrict individual freedoms, is necessary to institute and uphold an agreement. Formal sanctions are necessary to prevent cheating and are more likely to succeed where the backing is based on transparent, common norms. Agreements should not only be instruments of change but should establish processes for change, engaging a wide set of actors.

The institution of the nation-state has helped improve the well-being of many individuals, but at the cost of reduced global resilience. To address our common threats we need greater interaction among existing institutions, as well as new institutions, to help construct and maintain a global-scale social contract.

Our brain's fast response to morally objectionable statements.

Van Berkum et. al. make observations that go alongside the observations on moral conviction and religiosity mentioned in last friday's post.

How does the brain respond to statements that clash with a person's value system? We recorded event-related brain potentials while respondents from contrasting political-ethical backgrounds completed an attitude survey on drugs, medical ethics, social conduct, and other issues. Our results show that value-based disagreement is unlocked by language extremely rapidly, within 200 to 250 ms after the first word that indicates a clash with the reader's value system (e.g., "I think euthanasia is an acceptable/unacceptable…"). Furthermore, strong disagreement rapidly influences the ongoing analysis of meaning, which indicates that even very early processes in language comprehension are sensitive to a person's value system. Our results testify to rapid reciprocal links between neural systems for language and for valuation.

How much sleep do we need?

Recent work suggests a role for sleep in memory and/or synaptic plasticity. There is a large difference in how much sleep people need, ranging from less than 6 to more than 9 hours. Short sleepers are found in families, as are long sleepers, which suggests a genetic basis for sleep duration. He et al. now show that a mutation in a transcriptional factor, DEC2, is associated with short sleep in humans and mice. DEC2 is a transcription factor (protein that regulates gene function) involved in cell proliferation and differentiation, response to hypoxia, and circadian rhythms. Here is their abstract:

Sleep deprivation can impair human health and performance. Habitual total sleep time and homeostatic sleep response to sleep deprivation are quantitative traits in humans. Genetic loci for these traits have been identified in model organisms, but none of these potential animal models have a corresponding human genotype and phenotype. We have identified a mutation in a transcriptional repressor (hDEC2-P385R) that is associated with a human short sleep phenotype. Activity profiles and sleep recordings of transgenic mice carrying this mutation showed increased vigilance time and less sleep time than control mice in a zeitgeber time– and sleep deprivation–dependent manner. These mice represent a model of human sleep homeostasis that provides an opportunity to probe the effect of sleep on human physical and mental health.

Stimulate your waking memory with an electrical cap

A tiny oscillating electrical stimulation of which we are completely unaware (passed between electrodes on the forehead and jaw) can have the effect of enhancing memory consolidation during waking, an effect shown previously during sleep. The abstract of the open access PNAS article from Kirov et al.:

The application of transcranial slow oscillation stimulation (tSOS; 0.75 Hz) was previously shown to enhance widespread endogenous EEG slow oscillatory activity when applied during a sleep period characterized by emerging endogenous slow oscillatory activity. Processes of memory consolidation typically occurring during this state of sleep were also enhanced. Here, we show that the same tSOS applied in the waking brain also induced an increase in endogenous EEG slow oscillations (0.4–1.2 Hz), although in a topographically restricted fashion. Applied during wakefulness tSOS, additionally, resulted in a marked and widespread increase in EEG theta (4–8 Hz) activity. During wake, tSOS did not enhance consolidation of memories when applied after learning, but improved encoding of hippocampus-dependent memories when applied during learning. We conclude that the EEG frequency and related memory processes induced by tSOS critically depend on brain state. In response to tSOS during wakefulness the brain transposes stimulation by responding preferentially with theta oscillations and facilitated encoding.

Convergence of human and dog evolution, striving to please

Topál et al. perform some fascinating comparative studies that look in dogs for a curious error noted first by Piaget, who showed that 10-month-old humans infants will persist in looking for a toy in box A, where it has been placed several times, even after having been shown that it has been moved to box B, whereas 12-month-old infants do not. This phenomenon marks a developmental milestone in human infant cognition. Adult dogs, like human infants, will persevere in searching erroneously in box A because they regard the placement of the toy by a human experimenter as a social teaching event. By contrast, wolves rapidly learn correctly to search box B. They also observed that infants are able to generalize and thus still persevere when one experimenter places the toy in box A and a second then places the toy in box B. Dogs, however, display episodic learning, and a second experimenter reduces their searching choice to chance. Topál et al. suggest that sensitivity to human communicative signals stems from convergent social evolution of the Homo and the Canis genera.

MindBlog posts in the queue

I think I'll start passing along links to bits of work that I find interesting, but that are so far down my list of potential blog postings that they are unlikely to make it into a regular post. It seems a pity to let them disappear, because I'm aware that a few MindBlog readers with more specialized interests might be interested in some of them.

A study that suggests that increased gamma band (~40 Hz) event-related synchronization is related to, but not sufficient for, consciousness.

Clelland et al. show that synthesis of new nerve cells contributes to formation of spatial memories.

I Heard That Coming: Bendixen et al. show that event related potentials can signal the predictability of pattern in an upcoming a tone sequence.

Watching whales watching us. The evidence suggesting association between sonar and whale deaths is very convincing.

Scientists have now documented behaviors like tool use and cooperative hunting strategies among whales. Orcas, or killer whales, have been found to mourn their own dead. Just three years ago, researchers at Mount Sinai School of Medicine in New York discovered, in the brains of a number of whale species, highly specialized neurons that are linked to, among other things, the use of language and were once thought to be the exclusive property of humans and a few other primates. Indeed, marine biologists are now revealing not only the dizzying variety of vocalizations among a number of whale species but also complex societal structures and cultures.

Vorauer et al. on multiculturalism versus avoidance in influencing the tone of dominant/minority group interactions.

David Sloane Wilson and collaborators on how nice guys can finish last. From the summary in Nature:

Selfish individuals can profit from the altruism of others in their group, and can even exploit a group's resources so much that the resources become exhausted — an event known as the tragedy of the commons...Omar Eldakar, of the University of Arizona in Tucson, and his colleagues have now shown experimentally that aggressive mating in water striders (Aquarius remigis) can result in one such tragedy. Harassment of female water striders by males has previously been shown to drive away females, diminishing the mating success of all males in a group...The team built pools and manipulated the number of aggressive and nonaggressive males in each. They found that hyperaggressive males had greater mating success than those which were not aggressive within mixed pools. But as the number of hyperaggressive insects increased, the mating success of both types decreased.

Testosterone levels and long term career choices

From Sapienzaore et al., more on testosterone, gender, and risk aversion:

Women are generally more risk averse than men. We investigated whether between- and within-gender variation in financial risk aversion was accounted for by variation in salivary concentrations of testosterone and in markers of prenatal testosterone exposure in a sample of >500 MBA students. Higher levels of circulating testosterone were associated with lower risk aversion among women, but not among men. At comparably low concentrations of salivary testosterone, however, the gender difference in risk aversion disappeared, suggesting that testosterone has nonlinear effects on risk aversion regardless of gender. A similar relationship between risk aversion and testosterone was also found using markers of prenatal testosterone exposure. Finally, both testosterone levels and risk aversion predicted career choices after graduation: Individuals high in testosterone and low in risk aversion were more likely to choose risky careers in finance. These results suggest that testosterone has both organizational and activational effects on risk-sensitive financial decisions and long-term career choices.

Moral conviction and religiosity - different in the viscera

An interesting bit from Wisneski et al. :

Theory and research point to different ways moral conviction and religiosity connect to trust in political authorities to decide controversial issues of the day. Specifically, we predicted that stronger moral convictions would be associated with greater distrust in authorities such as the U.S. Supreme Court making the "right" decisions regarding controversial issues. Conversely, we predicted that stronger religiosity would be associated with greater trust in authorities. We tested these hypotheses using a survey of a nationally representative sample of Americans (N = 727) that assessed the degree to which people trusted the U.S. Supreme Court to rule on the legal status of physician-assisted suicide. Results indicated that greater religiosity was associated with greater trust in the U.S. Supreme Court to decide this issue, and that stronger moral convictions about physician-assisted suicide were associated with greater distrust in the U.S. Supreme Court to decide this issue. Also, the processes underlying religious trust and distrust based on moral convictions were more quick and visceral than slow and carefully considered.

The amygdala contributes to both aversive and appetitive arousal

Apparently the "scram!" and "go for it" emotions share some brain wiring. Shabel and Janak note that a large part of the amygdala, whose activation is usually associated with aversive emotions, is also activated during appetitive emotions. Thus there do not appear to be different circuits for the amygdala and autonomic nervous system arousal caused by positive versus aversive stimuli.

The amygdala is important for determining the emotional significance of environmental stimuli. However, the degree to which appetitive and aversive stimuli are processed by the same or different neuronal circuits within the amygdala remains unclear. Here we show that neuronal activity during the expression of classically conditioned appetitive and aversive emotional responses is more similar than expected by chance, despite the different sensory modalities of the eliciting stimuli. We also found that the activity of a large number of cells (> 43%) was correlated with blood pressure, a measure of emotional arousal. Together, our results suggest that a substantial proportion of neuronal circuits within the amygdala can contribute to both appetitive and aversive emotional arousal.