Posts Tagged ‘Brains and Behavior’

Twitter-Mining Captures Global Mood Patterns

29 Sep

Hourly changes in average positive (top) and negative (bottom) affect, arrayed by time (X-axis) and day (color). (Golder et al./Science)

An analysis of mood patterns distilled from half a billion tweets has produced a civilization-scale picture of how moods rise and fall in tandem, over time and across the world.

The details seem intuitive: positive feelings peaking in the morning, dipping during work and rising at day’s end; negativity accumulated over the workweek dissipating late on Friday afternoon. But they’ve proved surprisingly tricky to measure.

“There’s a whole generation of lab work that’s been inconclusive,” said sociologist Scott Golder of Cornell University, co-author of the tweet analysis published Sept. 29 in Science. “Every study would have something different to say about what they saw in their subjects’ affective rhythms.”

Many studies of how moods — or, more technically, positive and negative affect — change from minute to minute and day to day rely on self-reported surveys, which can be inconsistent if not misleading. The subjects of these studies also tend to be undergraduate students from western colleges, a group that’s not always representative of humanity at large.

'A systematic daily pattern of positive mood is a fundamental part of human existence.'
Twitter users, of course, don’t represent humanity either. But the culture- and globe-spanning size of the software platform’s community, and their constant generation of data that can be cross-referenced and correlated and otherwise computationally investigated, make them alluring to researchers.

“Twitter and Facebook, market transactions on eBay and Amazon: This is the stuff of everyday life” for much of the world, said Golder. “For a social scientist to have access to these records is a fantastic new opportunity.”

Using Linguistic Inquiry and Word Count, a text analysis program that quantifies the emotional content of statements, Golder and co-author Michael Macy analyzed a total of 509 million tweets generated over two years by 2.4 million people in 84 countries.

What Happens When

Before Scott Golder and Michael Macy decided to analyze tweets for mood, they were interested in analyzing tweets for patterns of behavior. Out of that work came a website,, that allows people to see how often a particular word is used at different times of the day and week.

"My favorite example is that bacon is more popular than sausage," said Golder, "but I'm counting on the internet population to visit and tell us their favorite examples." Co-author Macy's favorite search term is "happy hour," and the database also shows that Saturday night really is alright for fighting.
The resulting trends — positive moods starting high in the morning and declining through the day, peaking overall on weekends — held steady around the world.

Though the proposition that mood is governed by circadian and sleep cycles is widely accepted, other studies of mood fluctuations have found varying patterns, especially for positivity: A single afternoon peak, a day-long plateau, dual peaks at noon and evening or afternoon and evening, a mid-afternoon dip. Those discrepancies may be based largely on factors eliminated by the new study.

“The findings are exciting, particularly the robustness of the daily patterns in positive affect across vastly different geographical areas and cultures,” said Brant Hasler, a psychologist at the University of Pittsburgh School of Medicine. “A systematic daily pattern of positive mood is a fundamental part of human existence.”

However, said Hasler, “One must be very careful in extrapolating emotional state from a highly specific form of communication like Twitter.” People often present themselves strategically, and periods of especially intense emotion might be over- or under-represented.

The 140-character format itself might also be misleading, reducing the use of adjectives that would give more nuanced indicators of emotional tone, Hasler said.

According to Golder, analysis of crowd-generated datasets isn’t intended to replace other methodologies, but to complement them, providing yet one more way of investigating social patterns. Until recently, “there hasn’t been any practical way to observe large numbers of people in fine-grained detail,” he said.

“I applaud the creativity of the authors’ methods, and the ambitious scope of their sample,” said Hasler. “Now, we need to address two questions that follow from this: Why do these daily patterns exist? And how can we use this knowledge to improve our own lives and those of others?”

Image: Golder et al./Science

Citation: “Diurnal and Seasonal Mood Vary with Work, Sleep, and Daylength Across Diverse Cultures.” By Scott A. Golder and Michael W. Macy. Science, Vol. 333, September 30, 2011.

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Stubbornness Increases the More People Tell You You’re Wrong

20 Sep

By Duncan Geere, Wired UK

A group of psychologists working at HP’s Social Computing Research Group has found that humans are more likely to change their minds when fewer, rather than more, people disagree with them.

The team conducted an experiment asking several hundred people to choose between two pieces of furniture. After a varying amount of time, they were asked to choose again between the items, but told that a certain number of other people had preferred the opposite item.

The results showed that a small amount of social pressure to reverse an opinion was far more effective in getting people to change their minds than if the pressure was much greater. When an overwhelming number of people were shown as having made a different choice, people tended to stick with their original selections.

There are two conflicting theories of social influence at work here. Psychological reactance theory says that when we’re exposed to opposition to our beliefs, our self-preservation instincts kick in to make us stick to them. Social influence and conformity theory, however, suggests that being socially connected with others is important to humans, and we’ll reverse an opinion if we feel like it’ll let us “belong” to a group — the “peer pressure” effect.

The psychologists believe that the first theory becomes more powerful when we’re confronted by the opinions of many others, but the latter kicks in when we’re in a smaller social group. That chimes with earlier work done by the same team that shows that votes on rankings are influenced by our desire to impact the choices of others. We like to have an influence.

The next step for the team is to bring quality into the equation. Is it volume of recommendations, or the source of those recommendations, that carries more influence? If 1,000 strangers recommend something, but four close friends differ, who would you side with?

The full research paper is available on HP’s website.

Image: HP


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Cross-Species Gadget Tests Reveal Reason for Dolphin Tools

25 Jul

The dolphins of Australia’s Shark Bay, famed as Earth’s first marine tool-users, likely turned to gadgetry because echolocation couldn’t find the best fish, especially for hurried moms without time to hunt.

It was in 1984 that researchers first observed the dolphins fitting basket sponges over their beaks, then scraping through seafloor mud to disturb hidden fish. Research subsequently showed this behavior to be full-blown tool use, taught by mothers to their daughters and representing a profound difference in lifestyle between them and Shark Bay’s other bottlenoses.

A basic question remained unanswered, however: Though sponges clearly protected sensitive dolphin snouts from jagged pieces of rock and coral, why scrape seafloor at all? Why not rely on echolocation to pinpoint target prey?

In a study published July 20 in Public Library of Science ONE, biologists Eric Patterson and Janet Mann of Georgetown University set out to answer this question by mounting basket sponges on sticks and pushing them through Shark Bay seafloors, just as dolphins do.

Most fish scared from the muck were bottom-dwellers lacking swim bladders, the air-filled organs that help fish control their buoyancy. Compared to fish flesh, which interferes with acoustic signals just slightly more than water, air bladders stand out on sonar. Without them, bottom-dwelling fish are nearly invisible to echolocation. Hence the value of scraping through seafloors manually, and thus the need for a device that protects dolphin noses from scraping.

Hunting with sponges has allowed Shark Bay’s bottlenoses to fill an empty ecological niche, eating fish that other dolphins ignore, wrote Patterson and Mann. The findings also suggest why sponge foraging likely arose among Shark Bay’s females and has remained their province, taught by dolphin mothers to daughters rather than sons.

Whereas dolphin fathers are mostly absent, free to roam and chase prey in the open ocean, dolphin moms spend years with their calves. They need to put food on the figurative table but have little time to do it. Sponge foraging is convenient and nutritious, a family recipe for quick-but-delicious dinners passed on to daughters who will someday need it.

Image: Eric Patterson/PLoS ONE

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Citation: “The Ecological Conditions That Favor Tool Use and Innovation in Wild Bottlenose Dolphins (Tursiops sp.). By Eric Patterson & Janet Mann. PLoS ONE, July 20, 2011.


Engineered Viruses Boost Memory Recall in Mice

03 Mar

By John Timmer, Ars Technica

Memories fade with time, often to the annoyance of those who can’t recall important details. But scientists have now found a way to boost the recall of memories even after they’ve started to fade. Unfortunately, the method involves injecting an engineered virus directly into the brain, so those of us who are bad with names may want to wait a bit for the technique to be refined.

The work was done in rats, and the memories in question are associations between a specific taste — saccharine, for example — and an unpleasant stimulus, caused by injection of a nausea-inducing drug (the approach is called “conditioned taste aversion”). Unless the unpleasant association is reinforced, the memories will slowly fade with time, although the aversion doesn’t disappear entirely during the two-week period that the authors were looking at.

Two years ago, the same authors found that it was possible to radically accelerate this fading. By injecting a chemical that blocked a specific brain enzyme (protein kinase M ζ), the authors caused the rats to act as if they had never experienced the nausea, even if the memory manipulation took place 25 days after the conditioning. Most chemicals that interfere with memories tend to prevent them from being consolidated for long-term storage, but this chemical seemed to work even after the memory was firmly in place.

That’s potentially helpful, since some people have formed negative associations with harmless or even helpful items. Still, for most of us, it would be nice to think that fading memories could be resuscitated. Apparently, they can. The researchers have now done what’s effectively the converse experiment, and increased the activity of protein kinase M ζ. They did this by engineering a virus to express the gene for the kinase, and then infected specific areas of the brain involved in memory. All the infected cells had additional copies of the gene, and thus made more of its product.

The virus had exactly the effect that the authors would presumably have predicted. The virus was injected a week after the rats were given the aversion conditioning, when the memory would already be starting to fade, and the memory tests were done a week after that, yet rats showed a significantly improved retention of their memories. As the authors point out, the engineered virus boosted a memory that was formed before it was even present.

The memory molecule, PKMzeta, overexpressed in rat neurons. Red (left) shows PKMzeta while green (middle) is a fluorescent protein that shows nerve cells have been infected by viruses engineered to boost the memory molecule. Yellow (right) shows both the memory molecule and green fluorescent protein only overexpress at certain locations in the neuron. Weizmann Institute of Science/Science

Actually, you can make that memories, plural. The authors trained rats to avoid both saccharine and salty liquids over the course of three days, and then injected the virus a week after the last training. The memories of both of these trainings were enhanced by the presence of the viral protein kinase M ζ gene.

The authors can’t tell exactly what protein kinase M ζ is doing to increase the recall of memories, and suggest it could be either enhancing the association between taste and the unpleasant experience, or simply enhancing recall in general. Although they don’t mention it, their findings may also be limited to specific classes of memories, like the associations examined here.

That latter point makes the last sentence of the paper a bit over the top, as the authors suggest that a chemical that enhances protein kinase M ζ activity might make for a good treatment for memory disorders like amnesia and age-related decline. Until we have a clearer sense of how many types of memories it works for, that’s a bit premature. Fortunately, there are lots of ways to test the recall abilities of animals, many of which don’t involve negative associations. Hopefully, testing of the virus’ more general impact on memory is already underway.

Image: HIV (green dots), a member of the lentivirus genus. (C. Goldsmith/P. Feorino/E. L. Palmer/W. R. McManus/CDC)

Citation: “Enhancement of Consolidated Long-Term Memory by Overexpression of Protein Kinase Mζ in the Neocortex.” Reut Shema, Sharon Haramati, Shiri Ron, Shoshi Hazvi, Alon Chen,
Todd Charlton Sacktor and Yadin Dudai.
Science, Vol. 331, March 3, 2011. DOI: 10.1126/science.1200215

Source: Ars Technica

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Intelligent Individuals Don’t Make Groups Smarter

30 Sep

An early effort at defining general intelligence in groups suggests that individual brainpower contributes little to collective smarts.

Instead, it’s social awareness — the ability to pick up on emotional cues in others — that seems to determine how smart a group can be.

“We lack a shared criterion in predicting which groups will perform well and which won’t,” said psychologist Anita Woolley of Carnegie Mellon University. “There’s an underlying factor that seems to drive how individuals perform in multiple domains. I wondered if that was true of groups as well.”

In individuals, general intelligence is a measure of each person’s tendency to perform similarly on different types of cognitive tests, suggesting an underlying — general — intellectual competence. Exactly what produces those smarts, and how they correlate with biological and environmental factors, is controversial. But even if the causes are unclear, the evidence of individual general intelligence remains.

To determine whether something similar also operated in collective minds, Woolley’s team divided 600 test subjects into groups of two to five people, then had each group complete a variety of problem-solving tasks. Afterward the researchers interviewed the groups and each participant. They measured group cohesion and motivation, individual intelligence and personality, and other factors previously associated with group performance.

Their analysis, published Sept. 30 in Science, found several characteristics linked to group performance — and none involved individual intelligence. What mattered instead was the social sensitivity of individual members, the proportion of women (who tend to be more sensitive) in each group, and a balanced participation of conversation.

Gender and social sensitivity are linked, said Woolley, making emotional intelligence and conversation balance the most important factors in group performance. Not only was individual intelligence irrelevant, but group cohesion mattered little. Neither did motivation or happiness — a finding that most workers would find disconcerting.

“Some of our intuitions about how satisfaction and cohesion correlate with performance are a little misguided,” Woolley said. “But it’s not as if happiness and cohesion are bad.

In future research, Woolley plans to study how group intelligence is affected by size, and how the benefits of increased collaboration can reach a point of diminishing returns. She also wants to know how group intelligence changes when collaboration occurs online.

“The way we’re moving now, where everyone is interconnected, it calls into question the whole notion of what intelligence is, whether it’s so relevant what an individual can do by themselves” said Woolley. “It’s good to move the conversation in that direction.”

Image: Michael Cardus/Flickr.

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Citation: “Evidence for a Collective Intelligence Factor in the Performance of Human Groups.” By Anita Williams Woolley, Christopher F. Chabris, Alexander Pentland, Nada Hashmi, Thomas W. Malone. Science, Vol. 329 No. 6000, October 1, 2010.

Brandon Keim’s Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on an ecological tipping point project.