Lifespan changes in brain and cognition - early life sets the stage.

Walhovd et al. present a fascinating study on the origins of lifespan changes in brain and cognition, defining an extensive cortical region wherein surface area relates positively to general cognitive ability (GCA) in development. They find evidence that especially prefrontal and medial and posterolateral temporal clusters relate more strongly to GCA:

Significance

Brain and cognition change with age, with early gains and later declines. Attempts have been made to identify age-specific mechanisms, focusing on when and how declines begin in adults. However, even though general cognitive ability declines with age, there is a high stability in individuals’ cognitive ability relative to their same-age peers. Here we show that the relation between brain and cognition appears remarkably stable through the human lifespan. The cortical area change trajectories of higher and lower cognitive ability groups were parallel through life. Birth weight and parental education were identified as predictors, which provides novel evidence for stability in brain–cognition relationships throughout life, and indicates that early life factors impact brain and cognition for the entire life course.

Abstract

Neurodevelopmental origins of functional variation in older age are increasingly being acknowledged, but identification of how early factors impact human brain and cognition throughout life has remained challenging. Much focus has been on age-specific mechanisms affecting neural foundations of cognition and their change. In contrast to this approach, we tested whether cerebral correlates of general cognitive ability (GCA) in development could be extended to the rest of the lifespan, and whether early factors traceable to prenatal stages, such as birth weight and parental education, may exert continuous influences. We measured the area of the cerebral cortex in a longitudinal sample of 974 individuals aged 4–88 y (1,633 observations). An extensive cortical region was identified wherein area related positively to GCA in development. By tracking area of the cortical region identified in the child sample throughout the lifespan, we showed that the cortical change trajectories of higher and lower GCA groups were parallel through life, suggesting continued influences of early life factors. Birth weight and parental education obtained from the Norwegian Mother–Child Cohort study were identified as such early factors of possible life-long influence. Support for a genetic component was obtained in a separate twin sample (Vietnam Era Twin Study of Aging), but birth weight in the child sample had an effect on cortical area also when controlling for possible genetic differences in terms of parental height. Our results provide novel evidence for stability in brain–cognition relationships throughout life, and indicate that early life factors impact brain and cognition for the entire life course.

A summary graphic from the review by Jagust:

Conceptual model linking brain development, cognition, brain reserve, and late-life cognitive decline. Early life exposures and genes affect brain development, which in turn is related to GCA. GCA and education are related to one another, and provide brain reserve with advancing age. The graph demonstrates two individuals with high (blue) and low (red) brain reserve. Although the rate of their age-related cognitive decline is identical, the person with higher reserve crosses the threshold for dependence at an older age, thus experiencing a longer independent life. Early-life exposures, however, also confer indirect beneficial effects in addition to brain development, and these are likely to be salutary over the lifespan.

Neural link between affective understanding and interpersonal attraction

From Anders et al.:

Being able to comprehend another person’s intentions and emotions is essential for successful social interaction. However, it is currently unknown whether the human brain possesses a neural mechanism that attracts people to others whose mental states they can easily understand. Here we show that the degree to which a person feels attracted to another person can change while they observe the other’s affective behavior, and that these changes depend on the observer’s confidence in having correctly understood the other’s affective state. At the neural level, changes in interpersonal attraction were predicted by activity in the reward system of the observer’s brain. Importantly, these effects were specific to individual observer–target pairs and could not be explained by a target’s general attractiveness or expressivity. Furthermore, using multivoxel pattern analysis (MVPA), we found that neural activity in the reward system of the observer’s brain varied as a function of how well the target’s affective behavior matched the observer’s neural representation of the underlying affective state: The greater the match, the larger the brain’s intrinsic reward signal. Taken together, these findings provide evidence that reward-related neural activity during social encounters signals how well an individual’s “neural vocabulary” is suited to infer another person’s affective state, and that this intrinsic reward might be a source of changes in interpersonal attraction.

Statistics versus judgement.

This interesting website, pointed out to me by a friend, offers to send a daily gem of information to you, usually an excerpt from a published book...so, being a glutton for input streams, I signed up. I usually move on after glancing at a given day's topic, but this excerpt from Kahneman's "Thinking, Fast and Slow" I pass on, after excerpting even further:

In his book Clinical vs. Statistical Prediction: A The­oretical Analysis and a Review of the Evidence, psychoanalyst Paul Meehl gave evidence that statistical models almost always yield better predictions and diagnoses than the judgment of trained professionals. In fact, experts frequently give different answers when presented with the same information within a matter of a few minutes...Meehl's book provoked shock and disbelief among clinical psychologists, and the controversy it started has engendered a stream of research that is still flowing today, more than fifty years after its publication. The number of studies reporting comparisons of clinical and statistical predictions has increased to roughly two hundred, but the score in the contest between algorithms and humans has not changed. About 60% of the studies have shown significantly better accuracy for the algo­rithms. The other comparisons scored a draw in accuracy, but a tie is tanta­mount to a win for the statistical rules, which are normally much less expensive to use than expert judgment. No exception has been convinc­ingly documented.

The range of predicted outcomes has expanded to cover medical vari­ables such as the longevity of cancer patients, the length of hospital stays, the diagnosis of cardiac disease, and the susceptibility of babies to sudden infant death syndrome; economic measures such as the prospects of success for new businesses, the evaluation of credit risks by banks, and the future career satisfaction of workers; questions of interest to government agencies, including assessments of the suitability of foster parents, the odds of recidivism among juvenile offenders, and the likelihood of other forms of violent behavior; and miscellaneous outcomes such as the evaluation of scientific presentations, the winners of football games, and the future prices of Bor­deaux wine. Each of these domains entails a significant degree of uncer­tainty and unpredictability. We describe them as 'low-validity environments.' In every case, the accuracy of experts was matched or exceeded by a simple algorithm.

Another reason for the inferiority of expert judgment is that humans are incorrigibly inconsistent in making summary judgments of complex information. When asked to evaluate the same information twice, they frequently give different answers. The extent of the inconsistency is often a matter of real concern. Experienced radiologists who evaluate chest X-rays as 'normal' or 'abnormal' contradict themselves 20% of the time when they see the same picture on separate occasions. A study of 101 indepen­dent auditors who were asked to evaluate the reliability of internal corpo­rate audits revealed a similar degree of inconsistency. A review of 41 separate studies of the reliability of judgments made by auditors, pathologists, psy­chologists, organizational managers, and other professionals suggests that this level of inconsistency is typical, even when a case is reevaluated within a few minutes. Unreliable judgments cannot be valid predictors of anything

How China is changing your internet.

Here is a fascinating piece done by the NYTimes on the parallel universe of the internet in China.

 

The long lives of fairy tales.

I pass on some clips from a review by Pagel of work by Da Silva and Tehrani suggesting that some common fairy tales can be traced back 7,000 years or more, long before written languages appeared.

The Indo-European language family is a collection of related languages that probably arose in Anatolia and is now spoken all over western Eurasia. Its modern descendants include the Celtic, Germanic and Italic or Romance languages of western Europe, the Slavic languages of Russia and much of the Balkans, and the Indo-Iranian languages including Persian, as well as Sanskrit and most of the languages of the Indian sub-continent.

Language evolves faster than genes and language is predominantly vertically transmitted. Similarities and differences among vocabulary items, then, play the same role for cultural phylogenies as genes do for species trees, and provide greater resolution over short timescales. The Indo-European language tree is one of the most carefully studied of these language phylogenies

With a phylogenetic tree in hand, the authors recorded the presence or absence of each of 275 fairy tales in fifty Indo-European languages...Of the 275 tales, the authors discarded 199 after performing two tests of horizontal transmission...This left a group of 76 tales for which vertical transmission over the course of Indo-European history was the dominant signal for the patterns of shared presence and absence among contemporary societies. Hänsel and Gretel didn’t make this cut, but Beauty and the Beast did.

Evolutionary statistical methods were then applied to calculate a probability that each of the tales was present at each of various major historical splitting points on the Indo-European language phylogeny, taking account of uncertainty both in the phylogeny and in the reconstructed state. Calculating the ancestral probabilities depends only upon the distribution of tales in the contemporary languages in combination with the phylogenetic tree and so neatly gets around the problem that few if any tales exist as ‘fossil’ texts...Fourteen of the 76 tales, including Beauty and the Beast, were assigned a 50% or greater chance of having been present in the common ancestor of the entire western branch of the Indo-European languages. ..

A further four of the fourteen tales — but not Beauty and the Beast — had a 50% or greater probability of being present at the root of the Indo-European tree. A proto-Indo-European origin for these four tales represents a probable age of over 7,000 years. The tale with the highest probability (87%) of being present at the root was The Smith and the Devil whose story of a smith selling his soul to the devil is echoed today in the modern story of Faust. The authors suggest that metal working technology — as implied by the presence of a smith — could have been available this long ago.

Considering all these notions might lead us to ask why not more of the fairy tales appeared right back at the Indo-European root, or perhaps to wonder if some could go back even further. Perhaps some do. Flood myths appear in many of the world’s cultures, with some speculation that they date to the end of the last Ice Age perhaps 15,000 to 20,000 years ago when sea levels rose dramatically — if true, the western Bible story of Noah is just a comparatively recent hand-me-down.

Brain changes during hypnosis

Jiang et al. do the most detailed analysis to date of brain changes that are distinctive to people undergoing hypnosis:

Hypnosis has proven clinical utility, yet changes in brain activity underlying the hypnotic state have not yet been fully identified. Previous research suggests that hypnosis is associated with decreased default mode network (DMN) activity and that high hypnotizability is associated with greater functional connectivity between the executive control network (ECN) and the salience network (SN). We used functional magnetic resonance imaging to investigate activity and functional connectivity among these three networks in hypnosis. We selected 57 of 545 healthy subjects with very high or low hypnotizability using two hypnotizability scales. All subjects underwent four conditions in the scanner: rest, memory retrieval, and two different hypnosis experiences guided by standard pre-recorded instructions in counterbalanced order. Seeds for the ECN, SN, and DMN were left and right dorsolateral prefrontal cortex, dorsal anterior cingulate cortex (dACC), and posterior cingulate cortex (PCC), respectively. During hypnosis there was reduced activity in the dACC, increased functional connectivity between the dorsolateral prefrontal cortex (DLPFC;ECN) and the insula in the SN, and reduced connectivity between the ECN (DLPFC) and the DMN (PCC). These changes in neural activity underlie the focused attention, enhanced somatic and emotional control, and lack of self-consciousness that characterizes hypnosis.

Why do people infer “ought” from “is”?

Tworek and Cimpian offer an interesting perspective, doing experiments illustrating how we ascribe intrinsic value to what is customary. I give the start of their introduction setting the context, and then their abstract:

In his dissent from the Supreme Court decision recognizing a federal constitutional right for people to marry a same-sex partner, Chief Justice Roberts noted that heterosexual marriage has been around “for millennia” in societies all over the world: “the Kalahari Bushmen and the Han Chinese, the Carthaginians and the Aztecs”. A possible reading of this remark is that we should take what is typical as a signpost for what is good—how things ought to be.1 Whatever the correct interpretation here, the tendency to move seamlessly from “is” to “ought” is a mainstay of everyday reasoning. However, the validity of such “is”-to-“ought” inferences (or ought inferences) is at best uncertain. The mere existence of a pattern of behavior does not, by itself, reveal that the behavior is good.2 For instance, slavery and child labor were common throughout history, and still are in some parts of the world, yet it does not follow that people ought to engage in these practices. Why, then, do people frequently draw ought inferences and find them persuasive?

Abstract

People tend to judge what is typical as also good and appropriate—as what ought to be. What accounts for the prevalence of these judgments, given that their validity is at best uncertain? We hypothesized that the tendency to reason from “is” to “ought” is due in part to a systematic bias in people’s (nonmoral) explanations, whereby regularities (e.g., giving roses on Valentine’s Day) are explained predominantly via inherent or intrinsic facts (e.g., roses are beautiful). In turn, these inherence-biased explanations lead to value-laden downstream conclusions (e.g., it is good to give roses). Consistent with this proposal, results from five studies (N = 629 children and adults) suggested that, from an early age, the bias toward inherence in explanations fosters inferences that imbue observed reality with value. Given that explanations fundamentally determine how people understand the world, the bias toward inherence in these judgments is likely to exert substantial influence over sociomoral understanding.

How our brain and visceral monitoring encode the ‘self’

Babo-Rebelo et al. show that two seemingly distinct roles of the default brain network (DN), in self-related cognition on the one hand, and in the monitoring of bodily signals for autonomous function regulation, on the other, are functionally coupled. They do this by testing whether the amplitudes of heartbeat-evoked responses (HERs) during thoughts systematically covary with their self-relatedness, and whether this mechanism engages the DN. They employ two scales of self-relatedness. The “Me” scale described the content of the thought oriented either toward oneself or toward an external object, event, or person. The “I” scale described the engagement of the participant as the protagonist or the agent in the thought. Here is their abstract:

The default network (DN) has been consistently associated with self-related cognition, but also to bodily state monitoring and autonomic regulation. We hypothesized that these two seemingly disparate functional roles of the DN are functionally coupled, in line with theories proposing that selfhood is grounded in the neural monitoring of internal organs, such as the heart. We measured with magnetoencephalograhy neural responses evoked by heartbeats while human participants freely mind-wandered. When interrupted by a visual stimulus at random intervals, participants scored the self-relatedness of the interrupted thought. They evaluated their involvement as the first-person perspective subject or agent in the thought (“I”), and on another scale to what degree they were thinking about themselves (“Me”). During the interrupted thought, neural responses to heartbeats in two regions of the DN, the ventral precuneus and the ventromedial prefrontal cortex, covaried, respectively, with the “I” and the “Me” dimensions of the self, even at the single-trial level. No covariation between self-relatedness and peripheral autonomic measures (heart rate, heart rate variability, pupil diameter, electrodermal activity, respiration rate, and phase) or alpha power was observed. Our results reveal a direct link between selfhood and neural responses to heartbeats in the DN and thus directly support theories grounding selfhood in the neural monitoring of visceral inputs. More generally, the tight functional coupling between self-related processing and cardiac monitoring observed here implies that, even in the absence of measured changes in peripheral bodily measures, physiological and cognitive functions have to be considered jointly in the DN.

Leave the kids alone! A cognitive case for un-parenting

I want to pass on some clips from the text of a recent review by Glausiusz of Alison Gopnik's book on child-rearing "The Gardener and the Carpenter," and also from the NYTimes pieces by Gopnik summarizing its main arguments. (Her bottom line: "We don’t have to make children learn, we just have to let them learn." Clips from the book review:

An Amazon trawl for “parenting books” last month offered up 186,262 results. ..This is less genre than tsunami...Yet, as Alison Gopnik notes...the word parenting became common only in the 1970s, rising in popularity as traditional sources of wisdom about child-rearing — large extended families, for example — fell away...Gopnik...argues that the message of this massive modern industry is misguided.

It assumes that the 'right' parenting techniques or expertise will sculpt your child into a successful adult. But using a scheme to shape material into a product is the modus operandi of a carpenter, whose job it is to make the chair steady or the door true. There is very little empirical evidence, Gopnik says, that “small variations” in what parents do (such as whether they sleep-train) “have reliable and predictable long-term effects on who those children become”. Raising and caring for children is more like tending a garden: it involves “a lot of exhausted digging and wallowing in manure” to create a safe, nurturing space in which innovation, adaptability and resilience can thrive. Her approach focuses on helping children to find their own way, even if it isn't one you'd choose for them. The lengthy childhood of our species gives kids ample opportunity to explore, exploit and experiment before they are turned out into an unpredictable world.

Clips from Gopnik:

It’s not just that young children don’t need to be taught in order to learn. In fact, studies show that explicit instruction, the sort of teaching that goes with school and “parenting,” can be limiting. When children think they are being taught, they are much more likely to simply reproduce what the adult does, instead of creating something new.

My lab tried a different version of the experiment with the complicated toy. This time, though, the experimenter acted like a teacher. She said, “I’m going to show you how my toy works,” instead of “I wonder how this toy works.” The children imitated exactly what she did, and didn’t come up with their own solutions.

The children seem to work out, quite rationally, that if a teacher shows them one particular way to do something, that must be the right technique, and there’s no point in trying something new. But as a result, the kind of teaching that comes with schools and “parenting” pushes children toward imitation and away from innovation.

There is a deep irony here. Parents and policy makers care about teaching because they recognize that learning is increasingly important in an information age. But the new information economy, as opposed to the older industrial one, demands more innovation and less imitation, more creativity and less conformity.

In fact, children’s naturally evolved learning techniques are better suited to that sort of challenge than the teaching methods of the past two centuries.

Uncalculating cooperation is used to signal trustworthiness.

Jordan et al. devise an economic game experiment whose results help to explain a range of puzzling behaviors, such as extreme altruism, the use of ethical principles, and romantic love:

Significance

Human prosociality presents an evolutionary puzzle, and reciprocity has emerged as a dominant explanation: cooperating today can bring benefits tomorrow. Reciprocity theories clearly predict that people should only cooperate when the benefits outweigh the costs, and thus that the decision to cooperate should always depend on a cost–benefit analysis. Yet human cooperation can be very uncalculating: good friends grant favors without asking questions, romantic love “blinds” us to the costs of devotion, and ethical principles make universal moral prescriptions. Here, we provide the first evidence, to our knowledge, that reputation effects drive uncalculating cooperation. We demonstrate, using economic game experiments, that people engage in uncalculating cooperation to signal that they can be relied upon to cooperate in the future.

Abstract

Humans frequently cooperate without carefully weighing the costs and benefits. As a result, people may wind up cooperating when it is not worthwhile to do so. Why risk making costly mistakes? Here, we present experimental evidence that reputation concerns provide an answer: people cooperate in an uncalculating way to signal their trustworthiness to observers. We present two economic game experiments in which uncalculating versus calculating decision-making is operationalized by either a subject’s choice of whether to reveal the precise costs of cooperating (Exp. 1) or the time a subject spends considering these costs (Exp. 2). In both experiments, we find that participants are more likely to engage in uncalculating cooperation when their decision-making process is observable to others. Furthermore, we confirm that people who engage in uncalculating cooperation are perceived as, and actually are, more trustworthy than people who cooperate in a calculating way. Taken together, these data provide the first empirical evidence, to our knowledge, that uncalculating cooperation is used to signal trustworthiness, and is not merely an efficient decision-making strategy that reduces cognitive costs. Our results thus help to explain a range of puzzling behaviors, such as extreme altruism, the use of ethical principles, and romantic love.

A brain area crucial to coping with stress.

Sinha et al. show that “neuroflexibility” in a specific region of our ventromedial prefrontal cortex enhances resilience to stress - an increase in its activity dampens down brain areas initially activated by stress. Subjects showing lower levels of this flexibility exhibited higher levels of maladaptive coping behaviors in real life.

Active coping underlies a healthy stress response, but neural processes supporting such resilient coping are not well-known. Using a brief, sustained exposure paradigm contrasting highly stressful, threatening, and violent stimuli versus nonaversive neutral visual stimuli in a functional magnetic resonance imaging (fMRI) study, we show significant subjective, physiologic, and endocrine increases and temporally related dynamically distinct patterns of neural activation in brain circuits underlying the stress response. First, stress-specific sustained increases in the amygdala, striatum, hypothalamus, midbrain, right insula, and right dorsolateral prefrontal cortex (DLPFC) regions supported the stress processing and reactivity circuit. Second, dynamic neural activation during stress versus neutral runs, showing early increases followed by later reduced activation in the ventrolateral prefrontal cortex (VLPFC), dorsal anterior cingulate cortex (dACC), left DLPFC, hippocampus, and left insula, suggested a stress adaptation response network. Finally, dynamic stress-specific mobilization of the ventromedial prefrontal cortex (VmPFC), marked by initial hypoactivity followed by increased VmPFC activation, pointed to the VmPFC as a key locus of the emotional and behavioral control network. Consistent with this finding, greater neural flexibility signals in the VmPFC during stress correlated with active coping ratings whereas lower dynamic activity in the VmPFC also predicted a higher level of maladaptive coping behaviors in real life, including binge alcohol intake, emotional eating, and frequency of arguments and fights. These findings demonstrate acute functional neuroplasticity during stress, with distinct and separable brain networks that underlie critical components of the stress response, and a specific role for VmPFC neuroflexibility in stress-resilient coping.

To remember something better, wait, then exercise.

Another nice bit on what exercise can do for you.  The abstract from van Dongen et al.:

Highlights

•Performing aerobic exercise 4 hr after learning improved associative memory 

•Exercise at this time also increased hippocampal pattern similarity during retrieval 

•Exercise performed immediately after learning had no effect on memory retention 

•Exercise could have potential as a memory intervention in educational settings

Summary

Persistent long-term memory depends on successful stabilization and integration of new memories after initial encoding. This consolidation process is thought to require neuromodulatory factors such as dopamine, noradrenaline, and brain-derived neurotrophic factor. Without the release of such factors around the time of encoding, memories will decay rapidly. Recent studies have shown that physical exercise acutely stimulates the release of several consolidation-promoting factors in humans, raising the question of whether physical exercise can be used to improve memory retention. Here, we used a single session of physical exercise after learning to exogenously boost memory consolidation and thus long-term memory. Three groups of randomly assigned participants first encoded a set of picture-location associations. Afterward, one group performed exercise immediately, one 4 hr later, and the third did not perform any exercise. Participants otherwise underwent exactly the same procedures to control for potential experimental confounds. Forty-eight hours later, participants returned for a cued-recall test in a magnetic resonance scanner. With this design, we could investigate the impact of acute exercise on memory consolidation and retrieval-related neural processing. We found that performing exercise 4 hr, but not immediately, after encoding improved the retention of picture-location associations compared to the no-exercise control group. Moreover, performing exercise after a delay was associated with increased hippocampal pattern similarity for correct responses during delayed retrieval. Our results suggest that appropriately timed physical exercise can improve long-term memory and highlight the potential of exercise as an intervention in educational and clinical settings.

Distinguishing brain correlations from causes.

Many researchers, even though they know better, fall into the trap of assuming that correlations are causes (i.e., if brain activity X occurs just before or at the same time as action Y, it must be causing Y.) Katz et al. offer a nice example of this in looking at a brain region (the lateral intraparietal (LIP) cortex) whose activity reflects deciding on the direction of a moving set of dots. When this region was inactivated in rhesus macague monkeys performing a motion direction discrimination, it had no effect on decision making performance. But, when area MT (a motion detection area that shows only weak correlations with choices) was inhibited, performance was profoundly impaired. This suggests that larger networks should always be considered even in what seem to be simple decisions. The abstract:

During decision making, neurons in multiple brain regions exhibit responses that are correlated with decisions1. However, it remains uncertain whether or not various forms of decision-related activity are causally related to decision making. Here we address this question by recording and reversibly inactivating the lateral intraparietal (LIP) and middle temporal (MT) areas of rhesus macaques performing a motion direction discrimination task. Neurons in area LIP exhibited firing rate patterns that directly resembled the evidence accumulation process posited to govern decision making, with strong correlations between their response fluctuations and the animal’s choices. Neurons in area MT, in contrast, exhibited weak correlations between their response fluctuations and choices, and had firing rate patterns consistent with their sensory role in motion encoding. The behavioural impact of pharmacological inactivation of each area was inversely related to their degree of decision-related activity: while inactivation of neurons in MT profoundly impaired psychophysical performance, inactivation in LIP had no measurable impact on decision-making performance, despite having silenced the very clusters that exhibited strong decision-related activity. Although LIP inactivation did not impair psychophysical behaviour, it did influence spatial selection and oculomotor metrics in a free-choice control task. The absence of an effect on perceptual decision making was stable over trials and sessions and was robust to changes in stimulus type and task geometry, arguing against several forms of compensation. Thus, decision-related signals in LIP do not appear to be critical for computing perceptual decisions, and may instead reflect secondary processes. Our findings highlight a dissociation between decision correlation and causation, showing that strong neuron-decision correlations do not necessarily offer direct access to the neural computations underlying decisions.

Competition does not improve quality of work.

I have always been phobic about competition, especially in my scientific laboratory work, because I could feel its toxic effects on my risk taking, spontaneity and creativity. The reason that I made some useful contributions to understanding the chemistry of how we see is that I chose to emphasize questions and areas that were not in the current arenas of competition. I also felt the peer review processes involved were frequently biased (I served as a grant peer reviewer for many years.)  Balietti et al. design a laboratory experiment that produces results exactly matching my own experience:

Significance

Competition is an essential mechanism in increasing the effort and performance of human groups in real life. However, competition has side effects: it can be detrimental to creativity and reduce cooperation. We conducted an experiment called the Art Exhibition Game to investigate the effect of competitive incentives in environments where the quality of creative products and the amount of innovation allowed are decided through peer review. Our approach is general and can provide insights in domains such as clinical evaluations, scientific admissibility, and science funding. Our results show that competition leads to more innovation but also to more unfair reviews and to a lower level of agreement between reviewers. Moreover, competition does not improve the average quality of published works.  

Abstract

To investigate the effect of competitive incentives under peer review, we designed a novel experimental setup called the Art Exhibition Game. We present experimental evidence of how competition introduces both positive and negative effects when creative artifacts are evaluated and selected by peer review. Competition proved to be a double-edged sword: on the one hand, it fosters innovation and product diversity, but on the other hand, it also leads to more unfair reviews and to a lower level of agreement between reviewers. Moreover, an external validation of the quality of peer reviews during the laboratory experiment, based on 23,627 online evaluations on Amazon Mechanical Turk, shows that competition does not significantly increase the level of creativity. Furthermore, the higher rejection rate under competitive conditions does not improve the average quality of published contributions, because more high-quality work is also rejected. Overall, our results could explain why many ground-breaking studies in science end up in lower-tier journals. Differences and similarities between the Art Exhibition Game and scholarly peer review are discussed and the implications for the design of new incentive systems for scientists are explained.

Turn-taking skills unique to humans?

In yet another "humans are unique with respect to...." type article Melis, Tomasello and collaborators do experiments showing that humans differ in their ability to carry out long-term collaborative relationships that involve taking turns. I've been reading de Waal's recent book "Are we smart enough to know how smart animals are?" (which I highly recommend), which suggests that the "unique to humans" implicit in the title of the article of the article may not be appropriate, for the article demonstrates a more 'advanced' behavior in humans only in a specific paradyme involving just the two species. Potential turn taking behavior in other social animals, invertebrates as well as vertebrates, is still a possibility. The experiments:

...gave pairs of 3- and 5-year-old children and chimpanzees a collaboration task in which equal rewards could be obtained only if the members of a pair worked together first to reward one and then to reward the other. Neither species had previously been tested in a paradigm in which partners can distribute collaboratively produced rewards in “fair” ways only by taking turns being the sole beneficiary.

Here is their abstract:

Long-term collaborative relationships require that any jointly produced resources be shared in mutually satisfactory ways. Prototypically, this sharing involves partners dividing up simultaneously available resources, but sometimes the collaboration makes a resource available to only one individual, and any sharing of resources must take place across repeated instances over time. Here, we show that beginning at 5 years of age, human children stabilize cooperation in such cases by taking turns across instances of obtaining a resource. In contrast, chimpanzees do not take turns in this way, and so their collaboration tends to disintegrate over time. Alternating turns in obtaining a collaboratively produced resource does not necessarily require a prosocial concern for the other, but rather requires only a strategic judgment that partners need incentives to continue collaborating. These results suggest that human beings are adapted for thinking strategically in ways that sustain long-term cooperative relationships and that are absent in their nearest primate relatives.

Zapping your brain at home.

Mindblog has done a number of posts on transcranial electrical stimulation, usually reporting some beneficial cognitive or emotional effects (enter 'transcranial in the mindblog search box to see some of these). Because the technique requires only a 9 volt battery and a couple of wires, do it yourself (D.I.Y) kits have been marketed by a number of websites, but in general professional cognitive scientists caution against home brew science efforts because of potential deleterious effects of brain stimulation (though none have been reported). A recent Gray Matter piece by Anna Wexler reports her study over the past three years of D.I.Y. brain stimulators:

Their conflict with neuroscientists offers a fascinating case study of what happens when experimental tools normally kept behind the closed doors of academia — in this case, transcranial direct current stimulation — are appropriated for use outside them...To date, more than 1,000 peer-reviewed studies of the technique have been published. Studies have suggested, among other things, that the stimulation may be beneficial for treating problems like depression and chronic pain as well as enhancing cognition and learning in healthy individuals.

(I should point out my post noting a review by Farah that references one meta-analysis of the literature that does not support reported cognitive effects.)

Home use remains a subculture, part of the contemporary movement to “hack” one’s body — using supplements, brain-training games and self-tracking devices — to optimize productivity...I have conducted long interviews with dozens of D.I.Y. stimulators, both in person and via Skype; collected hundreds of questionnaire responses; and tracked online forums, websites, blogs and other platforms on which practitioners communicate. I’ve found that they are — for the most part — astute, inventive and resourceful....I’ve found (as I reported last year in The Journal of Medical Ethics) that users adhere to many of the protocols used in scientific studies.

The growth of D.I.Y. brain stimulation stems in part from a larger frustration with the exclusionary institutions of modern medicine, such as the exorbitant price of pharmaceuticals and the glacial pace at which new therapies trickle down to patients. For people without an institutional affiliation, even reading a journal article can be prohibitively expensive.

As neuroscientists continue to conduct brain stimulation experiments, publish results in journals and hold conferences, the D.I.Y. practitioners have remained quiet downstream listeners, blogging about scientists’ experiments, posting unrestricted versions of journal articles and linking to videos of conference talks. Some practitioners create their own manuals and guides based on published papers.

Added note: Want a brain stimulation conference? Check this out.

Worldwide internet access from light based wireless communication

Under the "random curious stuff" category in MindBlog's subtitle, I want to point to this NYTimes piece that fascinated me by using some simple analogies to explain complex technical issues. The work is a prelude to providing internet access anywhere on the planet, from the skies, using drones.:

In a paper published Tuesday in Optica, researchers from Internet.org’s Connectivity Lab have outlined a new type of light detector that can be used for free-space optical communication, a communication technique that uses light to send data wirelessly.

Free-space optical communication works by encoding communication signals in laser beams. Transmitters on the ground or in satellites shoot that light through the air to receivers that can decode the data. (To understand this on simple terms, think of encoding and sending information through morse code using a flashlight.)

...many free-space optical communication systems use smaller receivers with complex pointing and tracking systems. Because laser beams are narrow and travel in straight lines from point A to point B, these receivers have to continuously maneuver to catch laser beams head-on...Imagine trying to water a small potted plant with a water gun from different angles...To maximize the amount of water you catch, you have to constantly move the pot around.

The Facebook researchers’ solution to this problem is a light detector that doesn’t need pointing and tracking, but still allows for fast transmission...Facebook’s detector contains a spherical bundle of special fluorescent fibers. The bundle, somewhere between the size of a golf ball and tennis ball, is able to absorb blue laser light from any direction and re-emit it as green light. Because that green light is diffuse, it can then be funneled to a small receiver that converts the light back to data...imagine that instead of a water gun, you’re pointing a blow dart gun at a water balloon attached to a funnel over the potted plant. As soon as you hit the balloon, it pops and releases water. With the addition of the balloon, you’ve eliminated the need to move the pot around. You can shoot at the water balloon from any direction, and the plant will get watered.

Facebook’s new detector is able to achieve fast data rates of two gigabits per second — several orders of magnitude higher than those from radio frequencies — because light has a higher frequency than radio waves, and because the fluorescence process is fast. Free-space optical communication can also carry more information than radio communication, and is more secure because narrow laser beams are harder to intercept than wide radio waves.

The technology fits in with Facebook’s plans to beam internet access down from the skies using drones.

Abstract thinking in newborn ducklings!

Martinho and Kacelnik have shown that duckings imprint on the relational concept of "same or different." From Wasserman's perspective on the work:

Adhering to the adage that “actions speak more loudly than words,” scientists are deploying powerful behavioral tests that provide animals with nonverbal ways to reveal their intelligence to us. Although animals may not be able to speak, studying their behavior may be a suitable substitute for assaying their thoughts, and this in turn may allow us to jettison the stale canard that thought without language is impossible. Following this behavioral approach and using the familiar social learning phenomenon of imprinting, Martinho and Kacelnik report that mallard ducklings preferentially followed a novel pair of objects that conformed to the learned relation between a familiar pair of objects. Ducklings that had earlier been exposed to a pair of identical objects preferred a pair of identical objects to a pair of nonidentical objects; other ducklings that had been exposed to a pair of nonidentical objects preferred a pair of nonidentical objects to a pair of identical objects. Because the testing objects were decidedly unlike the training objects, Martinho and Kacelnik concluded that the ducklings had effectively understood the abstract concepts of “same” and “different.”

A duckling in the testing arena approaches a stimulus pair composed of “different” shapes.

This study is important for at least three reasons. First, it indicates that animals not generally believed to be especially intelligent are capable of abstract thought. Second, even very young animals may be able to display behavioral signs of abstract thinking. And, third, reliable behavioral signs of abstract relational thinking can be obtained without deploying explicit reward-and-punishment procedures.

Brain scans are prone to false positives.

An analysis by Eklund et al. has raised serious doubts about positive correlations reported in many of the 40,000 fMRI studies published in the last 2 decades (think of all those ‘This is your brain on politics’ type articles).

Significance

Functional MRI (fMRI) is 25 years old, yet surprisingly its most common statistical methods have not been validated using real data. Here, we used resting-state fMRI data from 499 healthy controls to conduct 3 million task group analyses. Using this null data with different experimental designs, we estimate the incidence of significant results. In theory, we should find 5% false positives (for a significance threshold of 5%), but instead we found that the most common software packages for fMRI analysis (SPM, FSL, AFNI) can result in false-positive rates of up to 70%. These results question the validity of some 40,000 fMRI studies and may have a large impact on the interpretation of neuroimaging results.

Abstract

The most widely used task functional magnetic resonance imaging (fMRI) analyses use parametric statistical methods that depend on a variety of assumptions. In this work, we use real resting-state data and a total of 3 million random task group analyses to compute empirical familywise error rates for the fMRI software packages SPM, FSL, and AFNI, as well as a nonparametric permutation method. For a nominal familywise error rate of 5%, the parametric statistical methods are shown to be conservative for voxelwise inference and invalid for clusterwise inference. Our results suggest that the principal cause of the invalid cluster inferences is spatial autocorrelation functions that do not follow the assumed Gaussian shape. By comparison, the nonparametric permutation test is found to produce nominal results for voxelwise as well as clusterwise inference. These findings speak to the need of validating the statistical methods being used in the field of neuroimaging.

Added note: Check out this NYTimes piece on these issues.

A must see Rube Goldberg machine