How groups make collective decisions?

How do you reach a consensus on which movie to watch when in a large group of friends? Initially, popular options get reinforced, and quorum sensing, where enough support for a given choice triggers the final decision, says a research.

Also, when a choice has more variations in how it is perceived, it is chosen less frequently, the study found.

Researchers from Carnegie Mellon University have developed a model that explains how groups make collective decisions. It has shown that positive feedback during the exploration process proves useful for making good and quick decisions.

"Throughout the presidential primary process in US, people are trying to find an ideal candidate in a crowded landscape. The person in the lead -- say Donald Trump -- gets more media coverage and attention, which could lead to more people thinking about voting for him based on name recognition," said co-researcher David Hagmann.

Using a Polya urn scheme -- a statistical model in which balls of different colours are repeatedly drawn from a container and previously picked colours become more likely to be drawn again -- the researchers were able to look at how long it takes to make decisions and calculate their accuracy.

"Most interesting, when one choice has more variation in how it is perceived, it is chosen less frequently, establishing systemic risk aversion," said co-researcher Russell Golman.

The model also helps in explaining how trends take off, such as the the success of word-of-mouth marketing tactics.

The study was published in the journal Science Advances.