© Andrew Yates / Reuters

Attitudes are contagious. People tend to copy each other's opinions. This is not a new idea, but only now have scientists begun to use computer models to try and understand the mechanism which facilitates this. And they say it has to do with large groups.The need for such research was to advance not only our understanding of how memory and perceptions are formed, but how they are shared; and more importantly, what other life processes this model could be applied to, such as habits, fashion and various fads.The findings have been published in the journal Psychological Science As the researchers explain, previous studies "have focused on small-scale social contexts. In the current study, we took a computational approach, circumventing the practical constraints of laboratory paradigms and providing novel results at scales unreachable by laboratory methodologies."The researchers incorporated known cognitive processes into computer models to test various groups, from two to 500 people in size. Information-sharing was simulated first in three-person groups. In those groups each participant would be programmed to memorize information shared by each of the other two members - an exercise born out of real-life studies on memory-related processes.Luhmann and Rajaram decided to expand their investigation to larger collaborative groups - up to 128 members. The effect of collaborative inhibition increased with group size. Each additional member would add to the group's overall recall effect, but performance decreased compared to that of the same individuals working alone.This proved one important principle: you cannot learn more information as a group by simply adding more individuals. The research team noticed that the gap between collaborative groups and combined individuals only decreased in groups of seven members and more.The next step was to learn how the mechanism works. To do this, Luhmann and Rajaram created a combined computer model simulating large networks full of distinct individuals, telling them to interact with those closest to them. As was suspected, two neighbors acquired similar knowledge to two members linked via a middle-man. Overall, that shared neighbor was found to be a transmitter of information as well.