Arquivo da tag: Tomada de decisão

Groups are often smarter without ‘opinion leaders’ (Futurity)

Equality may counteract the tendency toward groupthink, research suggests.

The classic “wisdom of crowds” theory goes like this: If we ask a group of people to guess an outcome, the group’s guess will be better than any individual expert. So, when a group tries to make a decision, in this case, predicting the outcome of an election, the group does a better job than experts. For market predictions, geopolitical forecasting, and crowdsourcing product ideas, the wisdom of crowds has been shown to even outperform industry experts.

“On average, opinion leaders were more likely to lead the group astray than to improve it.”

That is true—as long as people don’t talk to each other. When people start sharing their opinions, their conversations can lead to social influences that produce “groupthink” and destroy the wisdom of the crowd. So says the classic theory.

But Damon Centola, an associate professor in the University of Pennsylvania’s Annenberg School for Communication and School of Engineering and Applied Science and director of the Network Dynamics Group, discovered the opposite.

When people talk to each other, the crowd can get smarter, report Centola, PhD candidate Joshua Becker, and recent PhD graduate Devon Brackbill in Proceedings of the National Academy of Sciences.

Equal influence

“The classic theory says that if you let people talk to each other groups go astray. But,” says Centola, “we find that even if people are not particularly accurate, when they talk to each other, they help to make each other smarter. Whether things get better or worse depends on the networks.

“In egalitarian networks,” he says, “where everyone has equal influence, we find a strong social-learning effect, which improves the quality of everyone’s judgments. When people exchange ideas, everyone gets smarter. But this can all go haywire if there are opinion leaders in the group.”

An influential opinion leader can hijack the process, leading the entire group astray. While opinion leaders may be knowledgeable on some topics, Centola found that, when the conversation moved away from their expertise, they still remained just as influential. As a result, they ruined the group’s judgment.

“On average,” he says, “opinion leaders were more likely to lead the group astray than to improve it.”

Gut responses

The online study included more than 1,300 participants, who went into one of three experimental conditions. Some were placed into one of the “egalitarian” networks, where everyone had an equal number of contacts and everyone had equal influence. Others were placed into one of the “centralized” networks, in which a single opinion leader was connected to everyone, giving that person much more influence in the group. Each of the networks contained 40 participants. Finally, Centola had several hundred subjects participate in a “control” group, without any social networks.

In the study, all of the participants were given a series of estimation challenges, such as guessing the number of calories in a plate of food. They were given three tries to get the right answer. Everyone first gave a gut response.

Then, participants who were in social networks could see the guesses made by their social contacts and could use that information to revise an answer. They could then see their contacts’ revisions and revise their answers again. But this time it was their final answer. Participants were awarded as much as $10 based on the accuracy of their final guess. In the control group, participants did the same thing, but they were not given any social information between each revision.

“Everyone’s goal was to make a good guess. They weren’t paid for showing up,” Centola says, “only for being accurate.”

Patterns began to emerge. The control groups initially showed the classic wisdom of the crowd but did not improve as people revised their answers. Indeed, if anything, they got slightly worse. By contrast, the egalitarian networks also showed the classic wisdom of the crowd but then saw a dramatic increase in accuracy. Across the board, in network after network, the final answers in these groups were consistently far more accurate than the initial “wisdom of the crowd.”

“In a situation where everyone is equally influential,” Centola says, “people can help to correct each other’s mistakes. This makes each person a little more accurate than they were initially. Overall, this creates a striking improvement in the intelligence of the group. The result is even better than the traditional wisdom of the crowd! But, as soon as you have opinion leaders, social influence becomes really dangerous.”

In the centralized networks, Centola found that, when the opinion leaders were very accurate, they could improve the performance of the group. But even the most accurate opinion leaders were consistently wrong some of the time.

“Thus,” Centola says, “while opinion leaders can sometimes improve things, they were statistically more likely to make the group worse off than to help it.

“The egalitarian network was reliable because the people who were more accurate tended to make smaller revisions, while people who were less accurate revised their answers more. The result is that the entire crowd moved toward the more accurate people, while, at the same time, the more accurate people also made small adjustments that improved their score.”

Engineers and doctors

These findings on the wisdom of crowds have startling real-world implications in areas such as climate-change science, financial forecasting, medical decision-making, and organizational design.

For example, while engineers have been trying to design ways to keep people from talking to each other when making important decisions in an attempt to avoid groupthink, Centola’s findings suggest that what matters most is the network. A group of equally influential scientists talking to one another will likely lead to smarter judgments than might arise from keeping them independent.

He is currently working on implementing these findings to improve physicians’ decision-making. By designing a social network technology for use in hospital settings, it may be possible to reduce implicit bias in physicians’ clinical judgments and to improve the quality of care that they can offer.

Whether new technologies are needed to improve the way the groups talk to each other, or whether we just need to be cautious about the danger of opinion leaders, Centola says it’s time to rethink the idea of the wisdom of crowds.

“It’s much better to have people talk to each other and argue for their points of view than to have opinion leaders rule the crowd,” he says. “By designing informational systems where everyone’s voices can be heard, we can improve the judgment of the entire group. It’s as important for science as it is for democracy.”

Partial support for the work came from the Robert Wood Johnson Foundation.

Source: University of Pennsylvania

Decision-making process of viruses could lead to new antibiotic treatments (Science Daily)

February 6, 2017
Texas A&M AgriLife Communications
Humans face hundreds of decisions every day. But we’re not alone. Even the tiniest viruses also make decisions, and scientists are researching how they do so, to help lead to better treatments for some diseases. A team of scientists has discovered how the lambda phage decides what actions to take in its host, the E. coli bacterium.

The lambda phage prefers to destroy E. coli bacteria, which makes it a prime target for researchers. Dr. Lanying Zeng, left, and her graduate student Jimmy Trinh developed a four-color fluorescence reporter system to track it at the single-virus level. Credit: Texas A&M AgriLife Research photo by Kathleen Phillips

Humans face hundreds of decisions every day. But we’re not alone. Even the tiniest viruses also make decisions, and scientists are researching how they do so, to help lead to better treatments for some diseases.

In a study published Feb. 6 in the journal Nature Communications, Dr. Lanying Zeng and her team at Texas A&M AgriLife Research discovered how the lambda phage decides what actions to take in its host, the E. coli bacterium.

A phage is a virus that infects and replicates within a bacterium. Phages were first discovered about 100 years ago, but recently scientists have begun to study how they can be used to attack disease-causing bacteria, especially strains that have become more resistant to antibiotics.

So numerous and diverse are phages — numbering into the billions, according to various reports in the U.S. National Library of Medicine — that researchers are now hot on the trail of phages that have the potential for curing specific bacterial maladies.

The lambda phage, for example, prefers to destroy E. coli bacteria, which makes it a prime target for researchers. In tracking that target, Zeng’s graduate student Jimmy Trinh developed a four-color fluorescence reporter system to track it at the single-virus level. This was combined with computational models devised by Dr. Gábor Balázsi, a biomedical engineer and collaborator at Stony Brook University in Stony Brook, New York, “to unravel both the interactions between phages and how individual phages determine” the fate of a cell.

What they found was not unlike the decision-making process of humans. Sometimes the lambda phage cooperates with others. Sometimes it competes.

“Instead of just the cell making a decision, we found the phage DNAs themselves also make decisions,” Zeng said.

Through the process they developed, the scientists were able to determine that timing played a role in decision-making.

Zeng explained that some phages can have two cycles of reproduction: lytic and lysogenic.

In the lytic cycle, full copies of the virus are made inside of a cell, say an E. coli cell. When the phage-infected cell becomes full of the replicating viruses, it bursts open and is destroyed. In the lysogenic cycle, the phage’s DNA lives as part of the bacterium itself and both continue to reproduce as one. In short, lysis involves competition while lysogeny involves cooperation, she said.

So, a key to using phages to destroy bacteria, Zeng said, is to understand how and when a phage decides to “go lytic” on the pathogen.

“Say you have two lambda phages that infect one cell,” she said. “Each phage DNA within the cell is capable of making a decision. We want to know how they make a decision, whether one is more dominant than the other, whether they have any interactions and compete to see who will win, or whether they compromise.”

“They may even coexist for some time and then finally choose one decision,” she said. “But the phage is making a subcellular decision — and that is very important. There could be a lot of implications.”

The four-color fluorescence reporter system helped the researchers visualize that many factors contribute to the decision and that “from the evolutionary point of view, the phages want to optimize their own fitness or survival,” she said. “So that is why they choose either lytic or lysogenic to maximize or optimize their survival.”

The team identified some of the factors that led to competition and others that led to cooperation.

Zeng said because phage therapy is a growing field for seeking ways to treat bacteria, the results of this study will help other scientists advance their research.

“This is a paradigm for bacteriophages,” she said. “When we understand the mechanism of the decision more, that can lead to more applications and better characterization of other systems.”

Journal Reference:

  1. Jimmy T. Trinh, Tamás Székely, Qiuyan Shao, Gábor Balázsi, Lanying Zeng. Cell fate decisions emerge as phages cooperate or compete inside their hostNature Communications, 2017; 8: 14341 DOI: 10.1038/ncomms14341

Mudança climática (Folha de S.Paulo)


Eduardo Giannetti

Em “Reasons and Persons”, uma das mais inovadoras obras de filosofia analítica dos últimos 30 anos, o filósofo Derek Parfit propõe um intrigante “experimento mental”. A situação descrita é hipotética, mas ajuda a explicitar um ponto nevrálgico do maior desafio humano: limitar o aquecimento global a 2°C acima do nível pré-industrial até o final do século 21.

Imagine uma pessoa afivelada a uma cama com eletrodos colados em suas têmporas. Ao se girar um botão situado em outro local a corrente nos eletrodos aumenta em grau infinitesimal, de modo que o paciente não chegue a sentir. Um Big Mac gratuito é então ofertado a quem girar o botão. Ocorre, contudo, que quando milhares de pessoas fazem isso –sem que cada uma saiba dos outros– a descarga de energia produzida é suficiente para eletrocutar a vítima.

Quem é responsável pelo que? Algo tenebroso foi perpetrado, mas a quem atribuir a culpa? O efeito isolado de cada giro do botão é por definição imperceptível –são todos “torturadores inofensivos”. Mas o resultado conjunto dessa miríade de ações é ofensivo ao extremo. Até que ponto a somatória de ínfimas partículas de culpa se acumula numa gigantesca dívida moral coletiva?

A mudança climática em curso equivale a uma espécie de eletrocussão da biosfera. Quem a deseja? Até onde sei, ninguém. Trata-se da alquimia perversa de inumeráveis atos humanos, cada um deles isoladamente ínfimo, mas que não resulta de nenhuma intenção humana. E quem assume –ou deveria assumir– a culpa por ela? A maioria e ninguém, ainda que alguns sejam mais culpados que outros.

Os 7 bilhões de habitantes do planeta pertencem a três grupos: cerca de 1 bilhão respondem por 50% das emissões totais de gases-estufa, ao passo que os 3 bilhões seguintes por 45%. Os 3 bilhões na base da pirâmide de energia (metade sem acesso a eletricidade) respondem por apenas 5%. Por seu modo de vida e vulnerabilidade, este grupo –o único inocente– será o mais tragicamente afetado pelo “giro de botão” dos demais.

Descarbonizar é preciso. Segundo o recém-publicado relatório do painel do clima da ONU, limitar o aquecimento a 2°C exigirá cortar as emissões antropogênicas de 40% a 70% em relação a 2010 até 2050 e zerá-las até o final do século. Como chegar lá?

A complexidade do desafio é esmagadora. Contar com a gradual conscientização dos “torturadores inocentes” parece irrealista. Pagar para ver e apostar na tecnologia como tábua de salvação seria temerário ao extremo. O protagonista da ação, creio eu, deveria ser a estrutura de incentivos: precificar o carbono e colocar a força do sistema de preços para trabalhar no âmbito da descarbonização.

Number-crunching could lead to unethical choices, says new study (Science Daily)

Date: September 15, 2014

Source: University of Toronto, Rotman School of Management

Summary: Calculating the pros and cons of a potential decision is a way of decision-making. But repeated engagement with numbers-focused calculations, especially those involving money, can have unintended negative consequences.

Calculating the pros and cons of a potential decision is a way of decision-making. But repeated engagement with numbers-focused calculations, especially those involving money, can have unintended negative consequences, including social and moral transgressions, says new study co-authored by a professor at the University of Toronto’s Rotman School of Management.

Based on several experiments, researchers concluded that people in a “calculative mindset” as a result of number-crunching are more likely to analyze non-numerical problems mathematically and not take into account social, moral or interpersonal factors.

“Performing calculations, whether related to money or not, seemed to encourage people to engage in unethical behaviors to better themselves,” says Chen-Bo Zhong, an associate professor of organizational behavior and human resource management at the Rotman School, who co-authored the study with Long Wang of City University of Hong Kong and J. Keith Murnighan from Northwestern University’s Kellogg School of Management.

Participants in a set of experiments displayed significantly more selfish behavior in games where they could opt to promote their self-interest over a stranger’s after exposure to a lesson on a calculative economics concept. Participants who were instead given a history lesson on the industrial revolution were less likely to behave selfishly in the subsequent games. A similar but lesser effect was found when participants were first asked to solve math problems instead of verbal problems before playing the games. Furthermore, the effect could potentially be reduced by making non-numerical values more prominent. The study showed less self-interested behavior when participants were shown pictures of families after calculations.

The results may provide further insight into why economics students have shown more self-interested behavior in previous studies examining whether business or economics education contributes to unethical corporate activity, the researchers wrote.

The study was published in Organizational Behavior and Human Decision Processes.

Journal Reference:

  1. Long Wang, Chen-Bo Zhong, J. Keith Murnighan. The social and ethical consequences of a calculative mindset. Organizational Behavior and Human Decision Processes, 2014; 125 (1): 39 DOI: 10.1016/j.obhdp.2014.05.004

People Are Overly Confident in Their Own Knowledge, Despite Errors (Science Daily)

June 10, 2013 — Overprecision — excessive confidence in the accuracy of our beliefs — can have profound consequences, inflating investors’ valuation of their investments, leading physicians to gravitate too quickly to a diagnosis, even making people intolerant of dissenting views. Now, new research confirms that overprecision is a common and robust form of overconfidence driven, at least in part, by excessive certainty in the accuracy of our judgments.

New research confirms that overprecision is a common and robust form of overconfidence driven, at least in part, by excessive certainty in the accuracy of our judgments. (Credit: © pressmaster / Fotolia)

The research, conducted by researchers Albert Mannes of The Wharton School of the University of Pennsylvania and Don Moore of the Haas School of Business at the University of California, Berkeley, revealed that the more confident participants were about their estimates of an uncertain quantity, the less they adjusted their estimates in response to feedback about their accuracy and to the costs of being wrong.

“The findings suggest that people are too confident in what they know and underestimate what they don’t know,” says Mannes.

The new findings are published in Psychological Science, a journal of the Association for Psychological Science.

Research investigating overprecision typically involves asking people to come up with a 90% confidence interval around a numerical estimate — such as the length of the Nile River — but this doesn’t always faithfully reflect the judgments we have to make in everyday life. We know, for example, that arriving 15 minutes late for a business meeting is not the same as arriving 15 minutes early, and that we ought to err on the side of arriving early.

Mannes and Moore designed three studies to account for the asymmetric nature of many everyday judgments. Participants estimated the local high temperature on randomly selected days and their accuracy was rewarded in the form of lottery tickets toward a prize. For some trials, they earned tickets if their estimates were correct or close to the actual temperature (above or below); in other trials, they earned tickets for correct guesses or overestimates; and in some trials they earned tickets for correct guesses or underestimates.

The results showed that participants adjusted their estimates in the direction of the anticipated payoff after receiving feedback about their accuracy, just as Mannes and Moore expected.

But they didn’t adjust their estimates as much as they should have given their actual knowledge of local temperatures, suggesting that they were overly confident in their own powers of estimation.

Only when the researchers provided exaggerated feedback — in which errors were inflated by 2.5 times — were the researchers able to counteract participants’ tendency towards overprecision.

The new findings, which show that overprecision is a common and robust phenomenon, urge caution:

“People frequently cut things too close — arriving late, missing planes, bouncing checks, or falling off one of the many ‘cliffs’ that present themselves in daily life,” observe Mannes and Moore.

“These studies tell us that you shouldn’t be too certain about what’s going to happen, especially when being wrong could be dangerous. You should plan to protect yourself in case you aren’t as right as you think you are.”

Journal Reference:

  1. A. E. Mannes, D. A. Moore. A Behavioral Demonstration of Overconfidence in JudgmentPsychological Science, 2013; DOI: 10.1177/0956797612470700