Peer pressure on decision-making begins when individuals directly connected to each other first reach agreement, then – under the influence of peers not directly connected to them – the entire social group eventually tips into a social consensus.

An analysis of this process conducted by Ernesto Estrada, a visiting scholar at Emory’s Institute for Quantitative Theory and Methods (QuanTM), was recently published in the Nature journal Scientific Reports.

“Consider a teenager who is pressed by her friends into binge-drinking on a Saturday night,” says Estrada, noting that this represents direct pressure from peers. “However, she is also under indirect pressure, by seeing that many teenagers are doing the same thing every Saturday.”

This indirect pressure can make the difference in whether an individual copies a given attitude.

Using mathematical models, Estrada analyzed data taken from 15 networks – including U.S. school superintendents and Brazilian farmers – to outline how peer pressure shapes consensus, leadership and innovations in social groups.

“Reaching consensus about vital topics – such as global warming, the cost of health care and insurance systems, and healthy habits – is crucial for the evolution of our society,” says Estrada, who is a mathematician based at the University of Strathclyde in Scotland.

Read more at the University of Strathclyde.