Navigating the cyber-rapids: how social networks influence our decisions

Does being part of a social network change our decision-making process? A new study applied mathematical models to that question and says all equations point to "yes."

"The way in which information, decisions, and behaviors spread through a network is a fundamental social phenomenon," says study co-author Flavio Chierichetti.

These processes are similar to biological contagion, yet because behavioral trends are based on individual decision-making, they are more complex than direct biological contagion, he says.

The model he created with his team is based on two types of consumers depending on which of two products they prefer, assuming they each benefit from the use of their preferred product and a little from their second-choice product as well.

Each additional user who acquires the product increases the payoff the consumers will reap from it, meaning that the equation takes into account not only the preference of the individual consumer, but also the popularity of the product.

"Often, cascading behavior in a social network is guided by an entity that wants to achieve a certain outcome," says co-author Alessandro Panconesi.

"For example, a company might be trying to guide the adoption of a product by word-of-mouth effects, or a political movement might be trying to guide the success of its message in a population."

To understand how they manage to instigate a cascade, order and timing must be considered, says co-author Jon Kleinberg, for early adopters of the trend can influence the network, creating the next great wave.

"Consider for example how a company can choose to roll out a product at different times in different geographic areas or to different markets," says Kleinberg, who adds that the success of the cascade can depend on a strategic choice of timing.

While a considerable amount of research has been done about decision cascades, little is understood about how timing applies and the authors' aforementioned algorithms take it into account based on popular economic theory.

The authors' study was published in the Society for Industrial and Applied Mathematics (SIAM) Journal on Computing; more research will be necessary, they say, to take into account behavior at the individual level.