Eldest children are less cooperative, trusting, and reciprocating

In a brief review titled "Why your older brother didn't share" ScienceNow points to interesting work by Courtiol et al. Their abstract:

Explaining the behavioural variations observed between individuals is an important step for understanding the evolution of human cooperation and personality traits. Birth order is a potentially important variable that implies physical and cognitive differences between siblings and differential access to parental resources during childhood. These differences have been shown to influence several personality characteristics in adulthood. We tested the hypothesis that birth order can shape adult cooperative behaviours towards nonkin. An anonymous investment game was played by 510 unrelated students. The results of the game show that firstborns were less trustful and reciprocated less than others. No significant differences in trust or reciprocity were found among laterborn and only children based on birth order. Firstborn status was a better predictor of cooperativeness than age, sex, income or religion. These results constitute some of the first experimental evidence that birth order differences established within the family can persist in adult behaviour among nonkin. We discuss the implications of this finding for the evolution of human cooperation.

Spoken language and symbolic gestures processed by same brain areas

Xu et al perform MRI measurements that suggest that anterior and posterior perisylvian areas identified since the mid-19th century as the core of the brain's language system (including Broca's and Wernicke's area) may in fact function as a modality-independent semiotic system that plays a broader role in human communication, linking meaning with symbols whether these are words, gestures, images, sounds, or objects.

Symbolic gestures, such as pantomimes that signify actions (e.g., threading a needle) or emblems that facilitate social transactions (e.g., finger to lips indicating “be quiet”), play an important role in human communication. They are autonomous, can fully take the place of words, and function as complete utterances in their own right. The relationship between these gestures and spoken language remains unclear. We used functional MRI to investigate whether these two forms of communication are processed by the same system in the human brain. Responses to symbolic gestures, to their spoken glosses (expressing the gestures' meaning in English), and to visually and acoustically matched control stimuli were compared in a randomized block design....esults support a model in which bilateral modality-specific areas in superior and inferior temporal cortices extract salient features from vocal-auditory and gestural-visual stimuli respectively. However, both classes of stimuli activate a common, left-lateralized network of inferior frontal and posterior temporal regions in which symbolic gestures and spoken words may be mapped onto common, corresponding conceptual representations. We suggest that these anterior and posterior perisylvian areas, identified since the mid-19th century as the core of the brain's language system, are not in fact committed to language processing, but may function as a modality-independent semiotic system that plays a broader role in human communication, linking meaning with symbols whether these are words, gestures, images, sounds, or objects.

Figure - Common areas of activation for processing symbolic gestures and spoken language minus their respective baselines, identified using a random effects conjunction analysis. The resultant t map is rendered on a single subject T1 image: 3D surface rendering above, axial slices with associated z axis coordinates, below.

When seeing outweighs feeling.

Anders et al. make an interesting observation on patients who are blind in part of their visual field due to damage of a portion of the visual cortex. They still register negative feelings and somatic changes when a threatening stimulus is presented to their blind area, presumably due to sub-cortical pathways. However, when the visual stimulus is visible and receives full cortical processing, the patients’ phenomenal experience of affect does not closely reflect somatic changes. This decoupling of phenomenal affective experience and somatic changes is associated with an increase of activity in the left ventrolateral prefrontal cortex and a decrease of affect-related somatosensory activity. Here is their abstract:

Affective neuroscience has been strongly influenced by the view that a ‘feeling’ is the perception of somatic changes and has consequently often neglected the neural mechanisms that underlie the integration of somatic and other information in affective experience. Here, we investigate affective processing by means of functional magnetic resonance imaging in nine cortically blind patients. In these patients, unilateral postgeniculate lesions prevent primary cortical visual processing in part of the visual field which, as a result, becomes subjectively blind. Residual subcortical processing of visual information, however, is assumed to occur in the entire visual field. As we have reported earlier, these patients show significant startle reflex potentiation when a threat-related visual stimulus is shown in their blind visual field. Critically, this was associated with an increase of brain activity in somatosensory-related areas, and an increase in experienced negative affect. Here, we investigated the patients’ response when the visual stimulus was shown in the sighted visual field, that is, when it was visible and cortically processed. Despite the fact that startle reflex potentiation was similar in the blind and sighted visual field, patients reported significantly less negative affect during stimulation of the sighted visual field. In other words, when the visual stimulus was visible and received full cortical processing, the patients’ phenomenal experience of affect did not closely reflect somatic changes. This decoupling of phenomenal affective experience and somatic changes was associated with an increase of activity in the left ventrolateral prefrontal cortex and a decrease of affect-related somatosensory activity. Moreover, patients who showed stronger left ventrolateral prefrontal cortex activity tended to show a stronger decrease of affect-related somatosensory activity. Our findings show that similar affective somatic changes can be associated with different phenomenal experiences of affect, depending on the depth of cortical processing. They are in line with a model in which the left ventrolateral prefrontal cortex is a relay station that integrates information about subcortically triggered somatic responses and information resulting from in-depth cortical stimulus processing. Tentatively, we suggest that the observed decoupling of somatic responses and experienced affect, and the reduction of negative phenomenal experience, can be explained by a left ventrolateral prefrontal cortex-mediated inhibition of affect-related somatosensory activity.

A biological rationale for musical scales

An interesting article from Gill and Purves on musical scales, and how humans use only a few of the enormous number of possible tone combinations to create music. I found the illustrations to be fascinating and very educational:

Scales are collections of tones that divide octaves into specific intervals used to create music. Since humans can distinguish about 240 different pitches over an octave in the mid-range of hearing, in principle a very large number of tone combinations could have been used for this purpose. Nonetheless, compositions in Western classical, folk and popular music as well as in many other musical traditions are based on a relatively small number of scales that typically comprise only five to seven tones. Why humans employ only a few of the enormous number of possible tone combinations to create music is not known. Here we show that the component intervals of the most widely used scales throughout history and across cultures are those with the greatest overall spectral similarity to a harmonic series. These findings suggest that humans prefer tone combinations that reflect the spectral characteristics of conspecific vocalizations. The analysis also highlights the spectral similarity among the scales used by different cultures.

Rapid amygdala activation by fearful objects in our peripheral vision

Bayle et al. use Magnetoencephalography (MEG) to show that fearful objects presented to our peripheral field of vision while we are consciously looking at a central object cause rapid (80 msec) activation of the amygdala. If the fearful stimulus is presented to our central field of view and processed by the classical occipito-temporal visual pathway, it takes between 140 and 190 ms to register. Some clips:

In ecological situations, threatening stimuli often come out from the peripheral vision. Such aggressive messages must trigger rapid attention to the periphery to allow a fast and adapted motor reaction... Fearful and neutral faces were briefly presented in the central or peripheral visual field, and were followed by target faces stimuli. An event-related beamformer source analysis model was applied in three time windows following the first face presentations: 80 to 130 ms, 140 to 190 ms, and 210 to 260 ms. The frontal lobe and the right internal temporal lobe part, including the amygdala, reacted as soon as 80 ms of latency to fear occurring in the peripheral vision. For central presentation, fearful faces evoked the classical neuronal activity along the occipito-temporal visual pathway between 140 and 190 ms...Thus, the high spatio-temporal resolution of MEG allowed disclosing a fast response of a network involving medial temporal and frontal structures in the processing of fear related stimuli occurring unconsciously in the peripheral visual field.

A related study is offered by Sabatinelli et al., who examine the timing of emotional discrimination in the amygdala and ventral visual cortex.

Sequence of presentation influences our choice between alternatives.

FromMantonakis et al.:

When several choice options are sampled one at a time in a sequence and a single choice of the best option is made at the end of the sequence, which location in the sequence is chosen most often? We report a large-scale experiment that assessed tasting preferences in choice sets of two, three, four, or five wines. We found a large primacy effect—the first wine had a large advantage in the end-of-sequence choice. We also found that participants who were knowledgeable about wines showed a recency effect in the longer sequences.

The model they propose to explain their findings is interesting:

We propose that two biases operated within that sequential competitive evaluation process. First, a first-is-best bias accounts for the consistent primacy effect. Second, a bias in favor of each new wine among high-knowledge participants accounts for the recency effect, and for an interesting reason: Compared with the low-knowledge participants, the high-knowledge participants were more persistent in looking for a better wine later in the sequence—a plausible result of greater expertise. Thus, high-knowledge participants were likelier to make a comparison between their current favorite and the new wine when each new wine was sampled. Thus, there was a substantial chance that each new wine would beat the current favorite, and this habit produced the pronounced recency effect in longer sequences, especially for high-knowledge participants. For example, suppose that each new wine has a .30 chance of beating the current favorite, and the current favorite remains the preferred choice with a .70 probability. Note that these values are consistent with the size of the observed primacy effects (e.g., the first wine was chosen with approximately .70 probability in the two-option sets) and with the recency effects for the high-knowledge participants (the last wine was chosen with approximately .30 probability in the four-option and five-option sets).

We account for the lack of recency effects among the low-knowledge participants by proposing that they followed the pair-wise competitive-evaluation strategy less vigorously than the high-knowledge participants, eliminating the potential recency advantage. We speculate that the low-knowledge participants were more likely to be overwhelmed by the cognitive demands of the pair-wise competitive strategy as memory load and interference increased across the sampling trials.

The pair-wise model provides an almost perfect fit to the data if we add one more assumption about the comparison process. Thus far, we have assumed that all current favorites have a .70-versus-.30 advantage in all pair-wise comparisons. But if we suppose that the current-favorite advantage increases for later favorites (e.g., if the third option wins its pair-wise competition, its advantage increases to .75 vs. .25; if the fourth wins, its advantage is .80 vs. .20), then the model fits the data almost perfectly. This pair-wise-competition process model is impressive; its one failing is that it predicts a small recency effect for the three-option set for high-knowledge participants.

Experiencing our causality warps our sense of time.

Buehner et al. make the interesting observation that two events we know to be causally related are experienced as closer in time than similar unrelated events.  Thus, expectation warps our sense of time. :

According to widely held views in cognitive science harking back to David Hume, causality cannot be perceived directly, but instead is inferred from patterns of sensory experience, and the quality of these inferences is determined by perceivable quantities such as contingency and contiguity. We report results that suggest a reversal of Hume's conjecture: People's sense of time is warped by the experience of causality. In a stimulus-anticipation task, participants' response behavior reflected a shortened experience of time in the case of target stimuli participants themselves had generated, relative to equidistant, equally predictable stimuli they had not caused. These findings suggest that causality in the mind leads to temporal binding of cause and effect, and extend and generalize beyond earlier claims of intentional binding between action and outcome.

The year in ideas

The New York Times Magazine has just done its annual issue on what it selects, from A to Z, to be the most clever, important, silly or just plain weird innovations from all corners of the thinking world. Here are links to a few items that hooked me:

Drunken Ultimatums

Glow-in-the-dark dog

Good enough is the new great.

Google algorithm as an extinction model.

Guilty robots

Infant sleep is destiny

Literary Alzheimers 

The genius of crowds - massively collaborative mathematics

Random promotions 

This year's patents - a great humorous graphic

Modulation of our pain by emotions - cerebral and spinal sites

Our response to painful stimulation can be modulated by the emotional impact of viewing a pleasant or an unpleasant picture.  In an open access article, Roy et. al.  view the multiple sites associated with this effect - noting the central role of the right insula - by doing brain imaging of participants who received painful electric shocks while they viewed blocks of pleasant, unpleasant, or neutral pictures.:

Emotions have powerful effects on pain perception. However, the brain mechanisms underlying these effects remain largely unknown. In this study, we combined functional cerebral imaging with psychophysiological methods to explore the neural mechanisms involved in the emotional modulation of spinal nociceptive responses (RIII-reflex) and pain perception in healthy participants. Emotions induced by pleasant or unpleasant pictures modulated the responses to painful electrical stimulations in the right insula, paracentral lobule, parahippocampal gyrus, thalamus, and amygdala. Right insula activation covaried with the modulation of pain perception, consistent with a key role of this structure in the integration of pain signals with the ongoing emotion. In contrast, activity in the thalamus, amygdala, and several prefrontal areas was associated with the modulation of spinal reflex responses. Last, connectivity analyses suggested an involvement of prefrontal, parahippocampal, and brainstem structures in the cerebral and cerebrospinal modulation of pain by emotions. This multiplicity of mechanisms underlying the emotional modulation of pain is reflective of the strong interrelations between pain and emotions, and emphasizes the powerful effects that emotions can have on pain.

Why exercise makes you less anxious.

An article by Gretchen Reynolds summarizes work showing that exercise stimulates the synthesis of new brain cells that appear to be specifically buffered from exposure to stressful experience. Exercise also appears to cause beneficial changes in dopamine and serotonin regulation and the vulnerability to oxidative stress.

Stop me if I've told you this before......

Benedict Carey does a nice summary of work from Gopie and McCloud. Here is the Psychological Science Abstract of the work:

Everyone has recounted a story or joke to someone only to experience a nagging feeling that they may already have told this person this information. Remembering to whom one has told what, an ability that we term destination memory, has been overlooked by researchers despite its important social ramifications. Using a novel paradigm, we demonstrate that destination memory is more fallible than source memory—remembering the person from whom one has received information. In two experiments we increased and decreased self-focus, obtaining support for a theoretical framework that explains relatively poor destination memory performance as being the result of focusing attention on oneself and on the processes required to transmit information. Along with source memory, destination memory is an important component of episodic memory that plays a critical role in social interactions.

Why mindblog spends in the winter in Ft. Lauderdale...

View from the living room window of my Middleton, WI. home, just outside Madison, WI.  Seventeen inches of snow in Madison yesterday, today wind chill of -10 to -20 degrees fahrenheit. Getting to my Univ. of Wisconsin office would not be all that pleasant. Fort Lauderdale is sunny today with an unseasonable high of 87 degrees.

Political partisanship and perception of skin color tone

Interesting...from Caruso et al.:

People tend to view members of their own political group more positively than members of a competing political group. In this article, we demonstrate that political partisanship influences people's visual representations of a biracial political candidate's skin tone. In three studies, participants rated the representativeness of photographs of a hypothetical (Study 1) or real (Barack Obama; Studies 2 and 3) biracial political candidate. Unbeknownst to participants, some of the photographs had been altered to make the candidate's skin tone either lighter or darker than it was in the original photograph. Participants whose partisanship matched that of the candidate they were evaluating consistently rated the lightened photographs as more representative of the candidate than the darkened photographs, whereas participants whose partisanship did not match that of the candidate showed the opposite pattern. For evaluations of Barack Obama, the extent to which people rated lightened photographs as representative of him was positively correlated with their stated voting intentions and reported voting behavior in the 2008 Presidential election. This effect persisted when controlling for political ideology and racial attitudes. These results suggest that people's visual representations of others are related to their own preexisting beliefs and to the decisions they make in a consequential context.

Social isolation and inflammatory gene expression

My thanks to mindblog reader Ian for pointing out this article demonstrating how social isolation correlates with the expression of a large array of genes that elevate the risk of inflammatory disease. They did a DNA microarray analysis that identified 209 genes that were differentially expressed in circulating leukocytes from 14 high- versus low-lonely individuals, noting impaired transcription of glucocorticoid response genes and increased activity of pro-inflammatory transcription control pathways.

Men do everything they do to get laid?

Ted Maxwell of Intelligence Squared asks that I pass on this notice of a live online debate on evolutionary psychology at 18:45 GMT on Dec. 10.

Can it really be true that men do everything they do to get laid? Yes, argue the proponents of evolutionary psychology - because in their view the largely unconscious motive of human behaviour is to maximize reproductive success, which in men's case means getting sexual access to as many fertile women as possible. And so men - without necessarily being aware of it - do everything they do in order to get laid, and they are evolutionarily designed to behave in this way, because if they (and their ancestors) weren't, they wouldn't be here today. Women, on the other hand, have to be rather more careful about who they sleep with.

This, according to the theory, is why most millionaires, criminals and creative geniuses are men, why Intelligence Squared has such trouble finding good women speakers for its debates, and why middle-aged men tend to leave their wives for younger women. But what about the 50% of men who stick with their first marriage? And are we really saying that every creative endeavour - from the Sistine Chapel to the splitting of the atom - is nothing more than the manifestation of an underlying psychological impulse to copulate as much as possible?

My symbiosis with Google.

Yesterday's article by Brad Stone on Google in the NYTimes made me pause, yet again, to reflect on how utterly my professional and personal life have been altered by the 'free' services of this behemoth and 'the cloud,' most notably google search, Blogger, YouTube, gmail, Calendar and Contact synch of my iPhone and all my computers, etc. I have not filed away the hard copy of a scientific article in years, instead putting the PDF of any article of interest in the images file that supports this blog. I've just switched to their Chrome web browser which has blazing saddles speed compared with Firefox, Safari, Explorer, etc. (By the way, Kakutani has a review in the same NYTimes issue of "GOOGLED - The End of the World as We Know It" by Ken Auletta. titled "Still Counting the Ways to Infiltrate Daily Lives.")

The Brad Stone article describes partnerships with Twitter, Facebook and MySpace to bring updates from those services into its search index within seconds, so for example, you can see comments on the Copenhagen climate conference scrolling past as they are made. A new feature called Google Goggles, allows people to send Google a cellphone photograph of, say, a landmark or a book, and have information about the contents of the image returned to them instantly.

From Kakutani's review:

Because Google “enjoys a well-deserved reputation for earning the trust of users,” Mr. Auletta says, it is “hard to imagine an issue that could imperil the trust Google has achieved as quickly as could privacy.” He adds: “One Google executive whispers, ‘Privacy is an atomic bomb. Our success is based on trust.’ ”...If users, Mr. Auletta writes, “lost trust in Google, believed their private data was being exploited and shared with advertisers (or governments), the company regularly judged one of the world’s most trusted brands would commit suicide.”

“Google appears to be well positioned for the foreseeable future,” Mr. Auletta concludes, “but it is worth remembering that few companies maintain their dominance. At one point, few thought the Big Three auto companies would ever falter — or the three television networks or AT&T, IBM or AOL. For companies with histories of serious missteps — Apple, IBM — it was difficult to imagine that they’d rebound, until they did.”...In short, one of the few things it is impossible to Google is the future of Google.

The "Name-Ease" effect...

Interesting material from Labroo et al.:

We demonstrate that merely naming a research finding elicits feelings of ease (a "name-ease" effect). These feelings of ease can reduce or enhance the finding's perceived importance depending on whether people are making inferences about how understandable or how memorable the finding is. When people assess their understanding of a finding, feelings of ease reduce the finding's perceived importance. This is because people usually invest effort to understand important information but also mistakenly infer the reverse—namely, that information that requires effort to be understood is important. In contrast, when people assess the memorability of a finding, feelings of ease increase the finding's perceived importance. Because people usually recall important information easily, in this case they equate ease with importance. Psychological effects, economic principles, math theorems, jury cases, and decisions to fund medical research can all show these effects.

Primitive syntax in a monkey language?

Nicholas Wade points to some interesting work on the Campbell’s monkey in Tai Forest, Ivory Coast. (Later note: here is the link to the subsequent PNAS article.)

Our cooperative behavior is innate.

Nicholas Wade notes Tomasello's new book "Why We Cooperate." Helping behavior is observed in children and seems to be innate because it appears very early and before many parents start teaching children the rules of polite behavior. (The pictures shows a young child responding when an adult has dropped something.) Helping behavior can also be seen in infant chimpanzees under the right experimental conditions. Some clips:

Shared intentionality, in Dr. Tomasello’s view, is close to the essence of what distinguishes people from chimpanzees. A group of human children will use all kinds of words and gestures to form goals and coordinate activities, but young chimps seem to have little interest in what may be their companions’ minds...The shared intentionality lies at the basis of human society, Dr. Tomasello argues. From it flow ideas of norms, of punishing those who violate the norms and of shame and guilt for punishing oneself. Shared intentionality evolved very early in the human lineage, he believes, and its probable purpose was for cooperation in gathering food. Anthropologists report that when men cooperate in hunting, they can take down large game, which single hunters generally cannot do. Chimpanzees gather to hunt colobus monkeys, but Dr. Tomasello argues this is far less of a cooperative endeavor because the participants act on an ad hoc basis and do not really share their catch.

An interesting bodily reflection of humans’ shared intentionality is the sclera, or whites, of the eyes. All 200 or so species of primates have dark eyes and a barely visible sclera. All, that is, except humans, whose sclera is three times as large, a feature that makes it much easier to follow the direction of someone else’s gaze. Chimps will follow a person’s gaze, but by looking at his head, even if his eyes are closed. Babies follow a person’s eyes, even if the experimenter keeps his head still...Advertising what one is looking at could be a risk. Dr. Tomasello argues that the behavior evolved “in cooperative social groups in which monitoring one another’s focus was to everyone’s benefit in completing joint tasks.”..This could have happened at some point early in human evolution, when in order to survive, people were forced to cooperate in hunting game or gathering fruit. The path to obligatory cooperation — one that other primates did not take — led to social rules and their enforcement, to human altruism and to language.

Pre-natal androgens and risk taking...

Coates and Page follow up on a study I mentioned in an earlier post, this time examining risk taking as well as long-term profitability of traders in the City of London exchange:

Traders in the financial world are assessed by the amount of money they make and, increasingly, by the amount of money they make per unit of risk taken, a measure known as the Sharpe Ratio. Little is known about the average Sharpe Ratio among traders, but the Efficient Market Hypothesis suggests that traders, like asset managers, should not outperform the broad market. Here we report the findings of a study conducted in the City of London which shows that a population of experienced traders attain Sharpe Ratios significantly higher than the broad market. To explain this anomaly we examine a surrogate marker of prenatal androgen exposure, the second-to-fourth finger length ratio (2D:4D), which has previously been identified as predicting a trader's long term profitability. We find that it predicts the amount of risk taken by traders but not their Sharpe Ratios. We do, however, find that the traders' Sharpe Ratios increase markedly with the number of years they have traded, a result suggesting that learning plays a role in increasing the returns of traders. Our findings present anomalous data for the Efficient Markets Hypothesis.