Brain & Behavior

[Michael Scally MD]

A New Map of How We Think: Top Brain/Bottom Brain
Forget dated ideas about the left and right hemispheres. New research provides a more nuanced view of the brain
Science: A New Map of the Human Brain - WSJ.com

 

[zkt]

And there is the idea of peak experiences (Maslow).
(Not that I consider Psychology Today to be a scholarly publication.)

What Was Maslow's View of Peak-Experiences? | Psychology Today

 

[Michael Scally MD]

Papassotiropoulos A, Gerhards C, Heck A, et al. Human genome-guided identification of memory-modulating drugs. Proceedings of the National Academy of Sciences. Human genome–guided identification of memory-modulating drugs

In the last decade there has been an exponential increase in knowledge about the genetic basis of complex human traits, including neuropsychiatric disorders. It is not clear, however, to what extent this knowledge can be used as a starting point for drug identification, one of the central hopes of the human genome project.

The aim of the present study was to identify memory-modulating compounds through the use of human genetic information. We performed a multinational collaborative study, which included assessment of aversive memory—a trait central to posttraumatic stress disorder—and a gene-set analysis in healthy individuals. We identified 20 potential drug target genes in two genomewide-corrected gene sets: the neuroactive ligand–receptor interaction and the long-term depression gene set.

In a subsequent double-blind, placebo-controlled study in healthy volunteers, we aimed at providing a proof of concept for the genome-guided identification of memory modulating compounds. Pharmacological intervention at the neuroactive ligand–receptor interaction gene set led to significant reduction of aversive memory. The findings demonstrate that genome information, along with appropriate data mining methodology, can be used as a starting point for the identification of memory-modulating compounds.

 

[Michael Scally MD]

The Smarter You Are, The Stupider You Are
The Smarter You Are, The Stupider You Are : 13.7: Cosmos And Culture : NPR

Education is necessary if democracy is to flourish. What good is the free flow of information if people can't make sense of it? How can you vote your own interests if you don't understand the consequences of policy choices? How can you know what's best for you or your community?

A recent study by Yale's Dan M. Kahan and colleagues might be thought to call these truisms of democratic political culture into question. According to the finding, the better you are at reasoning numerically, the more likely you are to let your political bias skew your quantitative reasoning.

Put another way, the brainier you are, the better you can twist facts to your own pre-existing convictions. And that's what you will tend to do.

 

[Michael Scally MD]

[ame=http://www.youtube.com/watch?v=P3lIJZGU4Hc]Monkey uses thoughts to control virtual arms - YouTube[/ame]

 

[Michael Scally MD]

Schluter T, Winz O, Henkel K, et al. The Impact of Dopamine on Aggression: An [18F]-FDOPA PET Study in Healthy Males. J Neurosci 2013;33(43):16889-96. The Impact of Dopamine on Aggression: An [18F]-FDOPA PET Study in Healthy Males

Cerebral dopamine (DA) transmission is thought to be an important modulator for the development and occurrence of aggressive behavior. However, the link between aggression and DA transmission in humans has not been investigated using molecular imaging and standardized behavioral tasks. We investigated aggression as a function of DA transmission in a group of (N = 21) healthy male volunteers undergoing 6-[(18)F]-fluoro-l-DOPA (FDOPA)-positron emission tomography (PET) and a modified version of the Point Subtraction Aggression Paradigm (PSAP). This task measures aggressive behavior during a monetary reward-related paradigm, where a putative adversary habitually tries to cheat. The participant can react in three ways (i.e., money substraction of the putative opponent [aggressive punishment], pressing a defense button, or continuing his money-making behavior). FDOPA-PET was analyzed using a steady-state model yielding estimates of the DA-synthesis capacity (K), the turnover of tracer DA formed in living brain (kloss), and the tracer distribution volume (Vd), which is an index of DA storage capacity.

Significant negative correlations between PSAP aggressive responses and the DA-synthesis capacity were present in several regions, most prominently in the midbrain (r = -0.640; p = 0.002). Lower degrees of aggressive responses were associated with higher DA storage capacity in the striatum and midbrain. Additionally, there was a significant positive correlation between the investment into monetary incentive responses on the PSAP and DA-synthesis capacity, notably in the midbrain (r = +0.618, p = 0.003). The results suggest that individuals with low DA transmission capacity are more vulnerable to reactive/impulsive aggression in response to provocation.

 

[Michael Scally MD]

Scheele D, Wille A, Kendrick KM, et al. Oxytocin enhances brain reward system responses in men viewing the face of their female partner. Proceedings of the National Academy of Sciences. Oxytocin enhances brain reward system responses in men viewing the face of their female partner

The biological mechanisms underlying long-term partner bonds in humans are unclear. The evolutionarily conserved neuropeptide oxytocin (OXT) is associated with the formation of partner bonds in some species via interactions with brain dopamine reward systems. However, whether it plays a similar role in humans has as yet not been established.

Here, we report the results of a discovery and a replication study, each involving a double-blind, placebo-controlled, within-subject, pharmaco-functional MRI experiment with 20 heterosexual pair-bonded male volunteers.

In both experiments, intranasal OXT treatment (24 IU) made subjects perceive their female partner's face as more attractive compared with unfamiliar women but had no effect on the attractiveness of other familiar women.

This enhanced positive partner bias was paralleled by an increased response to partner stimuli compared with unfamiliar women in brain reward regions including the ventral tegmental area and the nucleus accumbens (NAcc). In the left NAcc, OXT even augmented the neural response to the partner compared with a familiar woman, indicating that this finding is partner-bond specific rather than due to familiarity.

Taken together, our results suggest that OXT could contribute to romantic bonds in men by enhancing their partner's attractiveness and reward value compared with other women.

 

[Michael Scally MD]

Sex differences are of high scientific and societal interest because of their prominence in behavior of humans and nonhuman species.

This work is highly significant because it studies a very large population of 949 youths (8–22 y, 428 males and 521 females) using the diffusion-based structural connectome of the brain, identifying novel sex differences.

The results establish that male brains are optimized for intrahemispheric and female brains for interhemispheric communication.

The developmental trajectories of males and females separate at a young age, demonstrating wide differences during adolescence and adulthood.

The observations suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.

Ingalhalikar M, Smith A, Parker D, et al. Sex differences in the structural connectome of the human brain. Proceedings of the National Academy of Sciences. Sex differences in the structural connectome of the human brain

Sex differences in human behavior show adaptive complementarity: Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills. Studies also show sex differences in human brains but do not explain this complementarity.

In this work, we modeled the structural connectome using diffusion tensor imaging in a sample of 949 youths (aged 8–22 y, 428 males and 521 females) and discovered unique sex differences in brain connectivity during the course of development. Connection-wise statistical analysis, as well as analysis of regional and global network measures, presented a comprehensive description of network characteristics.

In all supratentorial regions, males had greater within-hemispheric connectivity, as well as enhanced modularity and transitivity, whereas between-hemispheric connectivity and cross-module participation predominated in females. However, this effect was reversed in the cerebellar connections. Analysis of these changes developmentally demonstrated differences in trajectory between males and females mainly in adolescence and in adulthood.

Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.

 

[Michael Scally MD]

Can You Trust Your Memory?

Being highly imaginative animals, humans constantly recall past experiences. These internally generated stimuli sometimes get associated with concurrent external stimuli, which can lead to the formation of false memories.

Ramirez et al. identified a population of cells in the dentate gyrus of the mouse hippocampus that encoded a particular context and were able to generate a false memory and study its neural and behavioral interactions with true memories.

Optogenetic reactivation of memory engram–bearing cells was not only sufficient for the behavioral recall of that memory, but could also serve as a conditioned stimulus for the formation of an associative memory.

Ramirez S, Liu X, Lin P-A, et al. Creating a False Memory in the Hippocampus. Science 2013;341(6144):387-91. Creating a False Memory in the Hippocampus

Memories can be unreliable. We created a false memory in mice by optogenetically manipulating memory engram-bearing cells in the hippocampus. Dentate gyrus (DG) or CA1 neurons activated by exposure to a particular context were labeled with channelrhodopsin-2. These neurons were later optically reactivated during fear conditioning in a different context. The DG experimental group showed increased freezing in the original context, in which a foot shock was never delivered. The recall of this false memory was context-specific, activated similar downstream regions engaged during natural fear memory recall, and was also capable of driving an active fear response. Our data demonstrate that it is possible to generate an internally represented and behaviorally expressed fear memory via artificial means.

 

[Michael Scally MD]

Frenda, Steven J. and Knowles, Eric D. and Saletan, William and Loftus, Elizabeth F., False Memories of Fabricated Political Events (January 16, 2013). Journal of Experimental Social Psychology, Vol. 49, 2013; UC Irvine School of Law Research Paper No. 2013-87. Available at SSRN: False Memories of Fabricated Political Events by Steven J. Frenda, Eric D. Knowles, William Saletan, Elizabeth F. Loftus :: SSRN

In the largest false memory study to date, 5,269 participants were asked about their memories for three true and one of five fabricated political events. Each fabricated event was accompanied by a photographic image purportedly depicting that event. Approximately half the participants falsely remembered that the false event happened, with 27% remembering that they saw the events happen on the news. Political orientation appeared to influence the formation of false memories, with conservatives more likely to falsely remember seeing Barack Obama shaking hands with the president of Iran, and liberals more likely to remember George W. Bush vacationing with a baseball celebrity during the Hurricane Katrina disaster. A follow-up study supported the explanation that events are more easily implanted in memory when they are congruent with a person's preexisting attitudes and evaluations, in part because attitude-congruent false events promote feelings of recognition and familiarity, which in turn interfere with source attributions.

 

[Michael Scally MD]

Dark Personality Traits Revealed On Facebook - Analyses of your status updates on Facebook can show if you have psychopathic personality traits. Narcissistic traits can also be discerned from Facebook.

Highlights
• Latent Semantic Analysis was used to quantify Facebook status updates.
• Participants reported personality traits in the Dark Triad among others.
• The semantic content of the status updates predicted Psychopathy and Narcissism.
• The Dark Triad might be expressed in statuses as a social competition mechanism.

The study, based on personality tests and content analyses in status updates on Facebook for just over 300 Americans, is the first quantitative semantic study of its kind. In the study, the researchers ask whether the status updates can reveal the same dark personality traits as the psychological personality tests.

The Facebook users answered a scientific questionnaire with questions that test extrovert, neurotic, psychopathic, narcissistic and Machiavellian personality traits. They also sent in their 15 most recent status updates.

The contents of the status updates were then studied with algorithms for latent semantic analysis, which is a method for measuring the significance of words.

The researchers found that status updates contained information on the personality traits of psychopathy and narcissism.

Garcia D, Sikstrom S. The dark side of Facebook: Semantic representations of status updates predict the Dark Triad of personality. Personality and Individual Differences. The dark side of Facebook: Semantic representations of status updates predict the Dark Triad of personality

Using Latent Semantic Analysis, we quantified the semantic representations of Facebook status updates of 304 individuals in order to predict self-reported personality. We focused on, besides Neuroticism and Extraversion, the Dark Triad of personality: Psychopathy, Narcissism, and Machiavellianism. The semantic content of Facebook updates predicted Psychopathy and Narcissism. These updates had a more “odd” and negatively valanced content. Furthermore, Neuroticism, number of Facebook friends, and frequency of status updates were predictable from the status updates. Given that Facebook allows individuals to have major control in how they present themselves and draw benefits from these interactions, we conclude that the Dark Triad, involving socially malevolent behavior such as self-promotion, emotional coldness, duplicity, and aggressiveness, is manifested in Facebook status updates.

 

[Michael Scally MD]

Differential Effects of Global Versus Local Testosterone on Singing Behavior

Steroid hormones coordinate multiple behaviors into a functional response (reproduction, stress). It is easy to assess such coordination when comparing actions in different target tissues but is more of a challenge when numerous functions are combined in the brain.

Our study illustrates how steroids act on distinct cell groups to regulate separate components of a testosterone-dependent behavior, learned birdsong. Testosterone in the medial preoptic nucleus (POM) increased singing but not optimal song performance. Moreover, testosterone in the POM enhanced volumes of forebrain regions that control song, presumably reflecting the effect of activity-dependent plasticity.

Thus, optimal performance of a complex, learned behavior requires testosterone at multiple loci, and activity and/or transsynaptic influences may stimulate forebrain neuroplasticity.

Alward BA, Balthazart J, Ball GF. Differential effects of global versus local testosterone on singing behavior and its underlying neural substrate. Proceedings of the National Academy of Sciences 2016;110(48):19573-8. Differential effects of global versus local testosterone on singing behavior and its underlying neural substrate

Steroid hormones regulate multiple but distinct aspects of social behaviors. Testosterone (T) has multiple effects on learned courtship song in that it regulates both the motivation to sing in a particular social context as well as the quality of song produced. The neural substrate(s) where T acts to regulate the motivation to sing as opposed to other aspects of song has not been definitively characterized.

We show here that T implants in the medial preoptic nucleus (POM) of castrated male canaries (Serinus canaria) increase song rate but do not enhance acoustic features such as song stereotypy compared with birds receiving peripheral T that can act globally throughout the brain. Strikingly, T action in the POM increased song control nuclei volume, consistent with the hypothesis that singing activity induces neuroplasticity in the song control system independent of T acting in these nuclei. When presented with a female canary, POM-T birds copulated at a rate comparable to birds receiving systemic T but produced fewer calls and songs in her presence.

Thus, POM is a key site where T acts to activate copulation and increase song rate, an appetitive sexual behavior in songbirds, but T action in other areas of the brain or periphery (e.g., HVC, dopaminergic cell groups, or the syrinx) is required to enhance the quality of song (i.e., stereotypy) as well as regulate context-specific vocalizations.

These results have broad implications for research concerning how steroids act at multiple brain loci to regulate distinct sociosexual behaviors and the associated neuroplasticity.

 

[Michael Scally MD]

Kosinski M, Stillwell D, Graepel T. Private traits and attributes are predictable from digital records of human behavior. Proceedings of the National Academy of Sciences 2013;110(15):5802-5. Private traits and attributes are predictable from digital records of human behavior

We show that easily accessible digital records of behavior, Facebook Likes, can be used to automatically and accurately predict a range of highly sensitive personal attributes including: sexual orientation, ethnicity, religious and political views, personality traits, intelligence, happiness, use of addictive substances, parental separation, age, and gender. The analysis presented is based on a dataset of over 58,000 volunteers who provided their Facebook Likes, detailed demographic profiles, and the results of several psychometric tests. The proposed model uses dimensionality reduction for preprocessing the Likes data, which are then entered into logistic/linear regression to predict individual psychodemographic profiles from Likes. The model correctly discriminates between homosexual and heterosexual men in 88% of cases, African Americans and Caucasian Americans in 95% of cases, and between Democrat and Republican in 85% of cases. For the personality trait “Openness,” prediction accuracy is close to the test–retest accuracy of a standard personality test. We give examples of associations between attributes and Likes and discuss implications for online personalization and privacy.

 

[Michael Scally MD]

Gneezy U, Imas A. Materazzi effect and the strategic use of anger in competitive interactions. Proceedings of the National Academy of Sciences. Materazzi effect and the strategic use of anger in competitive interactions

We propose that individuals use anger strategically in interactions.

We first show that in some environments angering people makes them more effective in competitions, whereas in others, anger makes them less effective.

We then show that individuals anticipate these effects and strategically use the option to anger their opponents.

In particular, they are more likely to anger their opponents when anger negatively affects the opponents’ performances.

This finding suggests people understand the effects of emotions on behavior and exploit them to their advantage.

 

[Michael Scally MD]

Pupil Dilation Reflects Upcoming Choice and Individual Bias

Want to read someone’s mind?

Look at their pupils. A person about to answer “yes” to a question, especially if they are more used to answering “no,” will have more enlarged pupils than someone about to answer “no,” according to a new study.

Normally, pupils dilate when a person is in a darkened environment to let more light into the eye and allow better vision. But pupil size can also be altered by levels of signaling chemicals naturally produced by the brain.

In the study, scientists observed the pupils of 29 people as they pressed a “yes” or “no” button to indicate whether they’d seen a difficult-to-detect visual cue on a screen in front of them. When a person was deciding how to answer—in the seconds before pressing a button—their pupils grew larger.

Further, pupil dilation differentiates between “yes” and “no” choices for conservative subjects deciding yes against their bias. Thus, pupil dilation reveals the content of the evolving decision and the decision maker’s attitude.

These findings have important implications for interpreting decision-related brain activity. They also point to a possible role of neuromodulation in interacting with decision biases.

de Gee JW, Knapen T, Donner TH. Decision-related pupil dilation reflects upcoming choice and individual bias. Proceedings of the National Academy of Sciences. Decision-related pupil dilation reflects upcoming choice and individual bias

A number of studies have shown that pupil size increases transiently during effortful decisions. These decision-related changes in pupil size are mediated by central neuromodulatory systems, which also influence the internal state of brain regions engaged in decision making.

It has been proposed that pupil-linked neuromodulatory systems are activated by the termination of decision processes, and, consequently, that these systems primarily affect the postdecisional brain state.

Here, we present pupil results that run contrary to this proposal, suggesting an important intradecisional role. We measured pupil size while subjects formed protracted decisions about the presence or absence (“yes” vs. “no”) of a visual contrast signal embedded in dynamic noise.

Linear systems analysis revealed that the pupil was significantly driven by a sustained input throughout the course of the decision formation. This sustained component was larger than the transient component during the final choice (indicated by button press). The overall amplitude of pupil dilation during decision formation was bigger before yes than no choices, irrespective of the physical presence of the target signal. Remarkably, the magnitude of this pupil choice effect (yes > no) reflected the individual criterion: it was strongest in conservative subjects choosing yes against their bias.

We conclude that the central neuromodulatory systems controlling pupil size are continuously engaged during decision formation in a way that reveals how the upcoming choice relates to the decision maker’s attitude. Changes in brain state seem to interact with biased decision making in the face of uncertainty.

 

[03xx52]

Schluter T, Winz O, Henkel K, et al. The Impact of Dopamine on Aggression: An [18F]-FDOPA PET Study in Healthy Males. J Neurosci 2013;33(43):16889-96. The Impact of Dopamine on Aggression: An [18F]-FDOPA PET Study in Healthy Males

Cerebral dopamine (DA) transmission is thought to be an important modulator for the development and occurrence of aggressive behavior. However, the link between aggression and DA transmission in humans has not been investigated using molecular imaging and standardized behavioral tasks. We investigated aggression as a function of DA transmission in a group of (N = 21) healthy male volunteers undergoing 6-[(18)F]-fluoro-l-DOPA (FDOPA)-positron emission tomography (PET) and a modified version of the Point Subtraction Aggression Paradigm (PSAP). This task measures aggressive behavior during a monetary reward-related paradigm, where a putative adversary habitually tries to cheat. The participant can react in three ways (i.e., money substraction of the putative opponent [aggressive punishment], pressing a defense button, or continuing his money-making behavior). FDOPA-PET was analyzed using a steady-state model yielding estimates of the DA-synthesis capacity (K), the turnover of tracer DA formed in living brain (kloss), and the tracer distribution volume (Vd), which is an index of DA storage capacity.

Significant negative correlations between PSAP aggressive responses and the DA-synthesis capacity were present in several regions, most prominently in the midbrain (r = -0.640; p = 0.002). Lower degrees of aggressive responses were associated with higher DA storage capacity in the striatum and midbrain. Additionally, there was a significant positive correlation between the investment into monetary incentive responses on the PSAP and DA-synthesis capacity, notably in the midbrain (r = +0.618, p = 0.003). The results suggest that individuals with low DA transmission capacity are more vulnerable to reactive/impulsive aggression in response to provocation.

Do you think this is because of the dopamine responses to the reward center in the nucleus accumbens (NAcc)? The reactive behavior is due to the inability of the individuals to feel rewarded so they lash out to try and stimulate release of whatever neurotransmitter they can?

 

[Michael Scally MD]

The ugly truth - We all know our culture puts a premium on good looks – does that mean that the ugly are oppressed?
http://aeon.co/magazine/being-human/are-ugly-people-oppressed/



Brain Rewards Us for Looking at Pretty Faces - Your eyes are drawn to more attractive faces, and the almost inescapable result is that more attractive people have advantages in almost every aspect of life, from job interviews to prison sentencing.

But what drives us to crave beauty?

According to one theory, gazing upon beauty stimulates the brain’s ?-opioid receptors (MOR), thought to be a key part of our biochemical reward system.

At least in rodents, stimulating or inhibiting MOR neurotransmission not only tweaks the animals’ appetite for sex or food, but also the strength of their preferences for particular foods or mates.

Is our preference for pretty faces driven by the same biochemical reward circuit?

To find out, researchers invited 30 heterosexual men to browse a series of female faces on a computer. Each man received either a dose of the MOR-stimulating drug morphine, the opioid receptor–inhibiting drug naltrexone, or a placebo.

The results suggest that we seek out beautiful faces at least in part because our brains reward us.

Not only did stimulating MOR neurotransmission cause men to linger longer on faces that they rated as more beautiful, but the beauty rating also became more extreme, with beautiful faces rated as even more attractive relative to the rest of the faces.

Inhibiting MOR had the opposite effects.

The findings are yet more evidence that our social interactions are strongly influenced by the invisible hand of evolution, pushing us to find attractive mates.

But the question remains, how do we decide which face is attractive in the first place?

Chelnokova O, Laeng B, Eikemo M, et al. Rewards of beauty: the opioid system mediates social motivation in humans. Mol Psychiatry.
http://www.nature.com/mp/journal/vaop/ncurrent/full/mp20141a.html

Facial attractiveness is a powerful cue that affects social communication and motivates sexual behavior. Attractive people are both judged and treated more positively, reflecting the biased stereotypical notion that ‘beautiful is good’.

Indeed, beautiful faces are processed by the limbic reward system and according to the same economic principles as non-social rewards.

The human reward system has a high density of ?-opioid receptors, which have an important role in affiliation and attachment. Here, we causally test whether the healthy human opioid system mediates facial attractiveness preference.

 

[Michael Scally MD]

Morality is not just something that people learn. It is something we are all born with.

At birth, babies are endowed with compassion, with empathy, with the beginnings of a sense of fairness.

It is from these beginnings, he argues in his new book Just Babies, that adults develop their sense of right and wrong, their desire to do good — and, at times, their capacity to do terrible things.

Just Babies: The Origins of Good and Evil
Amazon.com: Just Babies: The Origins of Good and Evil eBook: Paul Bloom: Kindle Store

 

[Michael Scally MD]

The Courage of One’s [Convictions] Corrections
Motivated Reasoning & Revising False Beliefs
http://pointofcontroversy.com/2014/05/31/motivated-reasoning-revising-error/

Psychologists have raised doubts about whether we can reliably reason our way to true beliefs. Numerous studies suggest we’re prone to “motivated reasoning.” We sometimes argue against the facts due to unconscious goals that don’t aim at the truth.

The New Yorker and Vox interviewed http://www.dartmouth.edu/~nyhan/ and Dan Kahan, respectively, two researchers who study reasoning that’s motivated by a threatened sense of self. Kahan calls it “identity-protective cognition.” When facts clash with values that define a person’s sense of who she is, she’ll tend to “subconsciously resist” the facts and devise earnest arguments against them.

Kahan and Nyhan suggest ways to manage this sort of motivated reasoning, particularly as it affects public debate about scientific issues like climate change and vaccines. Nyhan endorses a science communication strategy that “avoids any broader issues of identity.” Kahan recommends one that “affirms rather than threatens people’s values [PDF].” I’ll explain these different approaches. I’ll then comment on another part of dealing with motivated reasoning—correcting the false beliefs it supports.

 

[Michael Scally MD]

Even the Editor of Facebook's Mood Study Thought It Was Creepy
"It's ethically okay from the regulations perspective, but ethics are kind of social decisions."
http://www.theatlantic.com/technolo...ooks-mood-study-thought-it-was-creepy/373649/


Facebook tinkered with users’ feeds for a massive psychology experiment. http://www.avclub.com/article/facebook-tinkered-users-feeds-massive-psychology-e-206324

Scientists at Facebook have published a paper showing that they manipulated the content seen by more than 600,000 users in an attempt to determine whether this would affect their emotional state.

It shows how Facebook data scientists tweaked the algorithm that determines which posts appear on users’ news feeds—specifically, researchers skewed the number of positive or negative terms seen by randomly selected users.

Facebook then analyzed the future postings of those users over the course of a week to see if people responded with increased positivity or negativity of their own, thus answering the question of whether emotional states can be transmitted across a social network.

Result: They can!

Which is great news for Facebook data scientists hoping to prove a point about modern psychology. It’s less great for the people having their emotions secretly manipulated.


Kramer ADI, Guillory JE, Hancock JT. Experimental evidence of massive-scale emotional contagion through social networks. Proceedings of the National Academy of Sciences 2014;111(24):8788-90. http://www.pnas.org/content/111/24/8788.full

Emotional states can be transferred to others via emotional contagion, leading people to experience the same emotions without their awareness. Emotional contagion is well established in laboratory experiments, with people transferring positive and negative emotions to others. Data from a large real-world social network, collected over a 20-y period suggests that longer-lasting moods (e.g., depression, happiness) can be transferred through networks [Fowler JH, Christakis NA (2008) BMJ 337:a2338], although the results are controversial. In an experiment with people who use Facebook, we test whether emotional contagion occurs outside of in-person interaction between individuals by reducing the amount of emotional content in the News Feed. When positive expressions were reduced, people produced fewer positive posts and more negative posts; when negative expressions were reduced, the opposite pattern occurred. These results indicate that emotions expressed by others on Facebook influence our own emotions, constituting experimental evidence for massive-scale contagion via social networks. This work also suggests that, in contrast to prevailing assumptions, in-person interaction and nonverbal cues are not strictly necessary for emotional contagion, and that the observation of others’ positive experiences constitutes a positive experience for people.