Scientists Discover Tipping Point for the Spread of Ideas

Scientists Discover Tipping Point for the Spread of Ideas

  9:46:00 AM    Science Lover

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Scientists at Rensselaer Polytechnic Institute have found that when just 10 percent of the population holds an unshakable belief, their belief will always be adopted by the majority of the society. The scientists, who are members of the Social Cognitive Networks Academic Research Center (SCNARC) at Rensselaer, used computational and analytical methods to discover the tipping point where a minority belief becomes the majority opinion. The finding has implications for the study and influence of societal interactions ranging from the spread of innovations to the movement of political ideals.

In this visualization, we see the tipping point where minority opinion (shown in red) quickly becomes majority opinion. Over time, the minority opinion grows. Once the minority opinion reached 10 percent of the population, the network quickly changes as the minority opinion takes over the original majority opinion (shown in green). (Credit: SCNARC/Rensselaer Polytechnic Institute)

"When the number of committed opinion holders is below 10 percent, there is no visible progress in the spread of ideas. It would literally take the amount of time comparable to the age of the universe for this size group to reach the majority," said SCNARC Director Boleslaw Szymanski, the Claire and Roland Schmitt Distinguished Professor at Rensselaer. "Once that number grows above 10 percent, the idea spreads like flame."

As an example, the ongoing events in Tunisia and Egypt appear to exhibit a similar process, according to Szymanski. "In those countries, dictators who were in power for decades were suddenly overthrown in just a few weeks."

The findings were published in the July 22, 2011, early online edition of the journal Physical Review E in an article titled "Social consensus through the influence of committed minorities."

An important aspect of the finding is that the percent of committed opinion holders required to shift majority opinion does not change significantly regardless of the type of network in which the opinion holders are working. In other words, the percentage of committed opinion holders required to influence a society remains at approximately 10 percent, regardless of how or where that opinion starts and spreads in the society.

To reach their conclusion, the scientists developed computer models of various types of social networks. One of the networks had each person connect to every other person in the network. The second model included certain individuals who were connected to a large number of people, making them opinion hubs or leaders. The final model gave every person in the model roughly the same number of connections. The initial state of each of the models was a sea of traditional-view holders. Each of these individuals held a view, but were also, importantly, open minded to other views.

Once the networks were built, the scientists then "sprinkled" in some true believers throughout each of the networks. These people were completely set in their views and unflappable in modifying those beliefs. As those true believers began to converse with those who held the traditional belief system, the tides gradually and then very abruptly began to shift.



"In general, people do not like to have an unpopular opinion and are always seeking to try locally to come to consensus. We set up this dynamic in each of our models," said SCNARC Research Associate and corresponding paper author Sameet Sreenivasan. To accomplish this, each of the individuals in the models "talked" to each other about their opinion. If the listener held the same opinions as the speaker, it reinforced the listener's belief. If the opinion was different, the listener considered it and moved on to talk to another person. If that person also held this new belief, the listener then adopted that belief.

"As agents of change start to convince more and more people, the situation begins to change," Sreenivasan said. "People begin to question their own views at first and then completely adopt the new view to spread it even further. If the true believers just influenced their neighbors, that wouldn't change anything within the larger system, as we saw with percentages less than 10."

The research has broad implications for understanding how opinion spreads. "There are clearly situations in which it helps to know how to efficiently spread some opinion or how to suppress a developing opinion," said Associate Professor of Physics and co-author of the paper Gyorgy Korniss. "Some examples might be the need to quickly convince a town to move before a hurricane or spread new information on the prevention of disease in a rural village."

The researchers are now looking for partners within the social sciences and other fields to compare their computational models to historical examples. They are also looking to study how the percentage might change when input into a model where the society is polarized. Instead of simply holding one traditional view, the society would instead hold two opposing viewpoints. An example of this polarization would be Democrat versus Republican.

The research was funded by the Army Research Laboratory (ARL) through SCNARC, part of the Network Science Collaborative Technology Alliance (NS-CTA), the Army Research Office (ARO), and the Office of Naval Research (ONR).

The research is part of a much larger body of work taking place under SCNARC at Rensselaer. The center joins researchers from a broad spectrum of fields -- including sociology, physics, computer science, and engineering -- in exploring social cognitive networks. The center studies the fundamentals of network structures and how those structures are altered by technology. The goal of the center is to develop a deeper understanding of networks and a firm scientific basis for the newly arising field of network science. More information on the launch of SCNARC can be found at http://news.rpi.edu/update.do?artcenterkey=2721&setappvar=page(1)

Szymanski, Sreenivasan, and Korniss were joined in the research by Professor of Mathematics Chjan Lim, and graduate students Jierui Xie (first author) and Weituo Zhang.

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How Social Pressure Can Affect What We Remember: Scientists Track Brain Activity as False Memories Are Formed

How Social Pressure Can Affect What We Remember: Scientists Track Brain Activity as False Memories Are Formed

  10:02:00 AM    Science Lover

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How easy is it to falsify memory? New research at the Weizmann Institute shows that a bit of social pressure may be all that is needed. The study, which appears in the journal Science, reveals a unique pattern of brain activity when false memories are formed -- one that hints at a surprising connection between our social selves and memory.

New research reveals a unique pattern of brain 
activity when false memories are formed -- one 
that hints at a surprising connection between 
our social selves and memory. (Credit: Image 
courtesy of Weizmann Institute of Science)

The experiment, conducted by Prof. Yadin Dudai and research student Micah Edelson of the Institute's Neurobiology Department with Prof. Raymond Dolan and Dr. Tali Sharot of University College London, took place in four stages. In the first, volunteers watched a documentary film in small groups. Three days later, they returned to the lab individually to take a memory test, answering questions about the film. They were also asked how confident they were in their answers.

They were later invited back to the lab to retake the test while being scanned in a functional MRI (fMRI) that revealed their brain activity. This time, the subjects were also given a "lifeline": the supposed answers of the others in their film viewing group (along with social-media-style photos). Planted among these were false answers to questions the volunteers had previously answered correctly and confidently. The participants conformed to the group on these "planted" responses, giving incorrect answers nearly 70% of the time.

But were they simply conforming to perceived social demands, or had their memory of the film actually undergone a change? To find out, the researchers invited the subjects back to the lab to take the memory test once again, telling them that the answers they had previously been fed were not those of their fellow film watchers, but random computer generations. Some of the responses reverted back to the original, correct ones, but close to half remained erroneous, implying that the subjects were relying on false memories implanted in the earlier session.

An analysis of the fMRI data showed differences in brain activity between the persistent false memories and the temporary errors of social compliance. The most outstanding feature of the false memories was a strong co-activation and connectivity between two brain areas: the hippocampus and the amygdala. The hippocampus is known to play a role in long-term memory formation, while the amygdala, sometimes known as the emotion center of the brain, plays a role in social interaction. The scientists think that the amygdala may act as a gateway connecting the social and memory processing parts of our brain; its "stamp" may be needed for some types of memories, giving them approval to be uploaded to the memory banks. Thus social reinforcement could act on the amygdala to persuade our brains to replace a strong memory with a false one.

Prof. Yadin Dudai's research is supported by the Norman and Helen Asher Center for Human Brain Imaging, which he heads; the Nella and Leon Benoziyo Center for Neurological Diseases; the Carl and Micaela Einhorn-Dominic Institute of Brain Research, which he heads; the Marc Besen and the Pratt Foundation, Australia; Lisa Mierins Smith, Canada; Abe and Kathryn Selsky Memorial Research Project; and Miel de Botton, UK. Prof. Dudai is the incumbent of the Sara and Michael Sela Professorial Chair of Neurobiology.

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People With Generalized Anxiety Disorder

People With Generalized Anxiety Disorder

  1:17:00 AM    Science Lover

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Scrambled connections between the part of the brain that processes fear and emotion and other brain regions could be the hallmark of a common anxiety disorder, according to a new study from the Stanford University School of Medicine. The findings could help researchers identify biological differences between types of anxiety disorders as well as such disorders as depression.

This image shows, in red, brain regions with stronger connections to the amygdala in patients with GAD, while the blue areas indicate weaker connectivity. The red corresponds to areas important for attention and may reflect the habitual use of cognitive strategies like worry and distraction in the anxiety patients. (Credit: Image courtesy of Stanford University Medical Center)

The study, which will be published Dec. 7 in the Archives of General Psychiatry, examined the brains of people with generalized anxiety disorder, or GAD, a psychiatric condition in which patients spend their days in a haze of worry over everyday concerns. Researchers have known that the amygdala, a pair of almond-sized bundles of nerve fibers in the middle of the brain that help process emotion, memory and fear, are involved in anxiety disorders like GAD. But the Stanford study is the first to peer close enough to detect neural pathways going to and from subsections of this tiny brain region.

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Heart Cells on Lab Chip Display 'Nanosense' That Guides Behavior

Heart Cells on Lab Chip Display 'Nanosense' That Guides Behavior

  11:30:00 PM    Science Lover

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Johns Hopkins biomedical engineers, working with colleagues in Korea, have produced a laboratory chip with nanoscopic grooves and ridges capable of growing cardiac tissue that more closely resembles natural heart muscle. Surprisingly, heart cells cultured in this way used a "nanosense" to collect instructions for growth and function solely from the physical patterns on the nanotextured chip and did not require any special chemical cues to steer the tissue development in distinct ways.

Johns Hopkins researchers developed this chip to culture heart cells that more closely resemble natural cardiac tissue. (Credit: Will Kirk/homewoodphoto.jhu.edu)

The scientists say this tool could be used to design new therapies or diagnostic tests for cardiac disease.

The device and experiments using it were described online in the Early Edition of Proceedings of the National Academy of Sciences. The work, a collaboration with Seoul National University, represents an important advance for researchers who grow cells in the lab to learn more about cardiac disorders and possible remedies.

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Thought-propelled wheelchairs, soon

Thought-propelled wheelchairs, soon

  8:50:00 PM    Science Lover

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Italian researchers are in talks with manufacturers to make the system an affordable and common-place reality in the next 5-10 years

The user is connected via electrodes on his scalp, and sends a signal by concentrating for a few seconds on a list of desired destination, displayed on a screen.

In a project spanning three years, Italian researchers at Milan’s Polytechnical Institute Artificial Intelligence and Robotics laboratory have developed a wheelchair that obeys mental signals sent via a computer.

The user, who is connected to a computer through electrodes on his or her scalp, can send signals to the wheelchair by concentrating for a few seconds on the name of the desired destination – kitchen, bedroom, bathroom – displayed on a screen.

The system then uses a preset program to take the user to the desired destination.

“We don’t read minds, but the brain signal that is sent,” said Professor Matteo Matteucci who was part of the project.

The chair, he informed, is also equipped with two laser beams that can detect obstacles.

The Milan lab is already in contact with companies that could produce a commercial prototype that could cater to quadriplegics, Matteucci disclosed.

“Still, it could take between five and 10 years for this system to be available widely,” he said, adding that such a wheelchair would cost only 10 per cent more than a classic motorised version.

Research to develop the so-called Brain Computer Interface began in the early 1980s around the world.

Professor Matteo Matteucci (right) and PhD student Bernardo Dal Seno, wearing a skullcap mounted with electrodes and wired to a computer as he sits on a special wheel chair. Italian boffins have developed a wheelchair that obeys mental signals sent to a computer.

Matteucci said a handful of other researchers were working on similar projects to his, including the Federal Polytechnic School in Lausanne, Switzerland.

“Eventually, a research consortium should be set up that will use all these projects as a basis for finding the best approach,” he said.

“We’ve now started work on getting the chair to operate outdoors using a GPS,” Matteucci added.

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World's smallest periscopes

World's smallest periscopes

  2:05:00 AM    Science Lover

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A team of scientists has designed the world's tiniest version of the periscope to peer at cells and other micro-organisms from all the sides at once.

"With an off-the-shelf laboratory microscope you only see cells from one side, the top," said Chris Janetopoulos, assistant professor of biological sciences at the Vanderbilt University (VU) and member of the research team.

"Now not only can we see the tops of cells, we can view their sides as well - something biologists almost never see," he added.

The researchers dubbed their devices "mirrored pyramidal wells". They consist of pyramidal-shaped cavities moulded into silicon whose interior surfaces are coated with a reflective layer of gold or platinum.

They are about the width of a human hair and can be made in a range of sizes to view different-sized objects. When a cell is placed in such a well and viewed with a regular microscope, the researcher can see several sides simultaneously.

"This technology is exciting because these mirrored wells can be made at very low cost, unlike other, more complex methods for 3D microscopy," said VU assistant professor Kevin Seale.

"This could easily become as ubiquitous as the microscope slide and could replace more expensive methods currently used to position individual cells," said Ron Reiserer, lab manager at the Vanderbilt Institute for Integrative Biosystems Research and Education (VIIBRE) who helped design the protocol used to make the micropyramids.

The Vanderbilt group is not the first to make microscopic pyramidal wells, but it is the first to apply them to make 3D images of microorganisms, said a Vanderbilt release.

These findings were published in the Journal of Microscopy.

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