The staffs from government, company and any other social organization always try to evaluate and predict exactly the individuals' judgments, preferences and selections. For example, the CEOs in Hollywood puzzle out how they can make next superstar [ 1 ], while Google works hard behind closed doors to sense more keywords as accurately as they can in order to be a net winner to take all advertisements [ 2 ]. However, recent experimental study shows a result as expected: introducing certain designed interference or social influence can take an effect on the behavior of single individuals, however, the dynamical interaction between the offered influence and the individuals is complicate, which makes the outcome unpredictable.

In Science published on 10 February 2006 [ 3 ], Matthew J. Salganik, Peter Sheridan Dodds and Duncan J. Watts from Columbia University in New York described an elegant study on individuals' preferences for downloading the songs via internet. The researchers tried for figuring the pattern of the interactive social processes mathematically. They created a website saving with generally unknown songs by unfamiliar singers for freely listening, rating and downloading by 14,341 test's participants either with or without knowledge of previous participants' choices. Subjects were randomly assigned to different groups. Individuals in only some groups were informed about how many times others in their group had downloaded each song.

With knowledge of other participants' choices, they found that individuals' preferences were influenced and the extent of social influence had important consequences for the collective outcomes that emerged, that is, "Increasing the strength of social influence increased both inequality and unpredictability of success. Success was also only partly determined by quality: The best songs rarely did poorly, and the worst rarely did well, but any other result was possible", said the authors.

"As Salganik et al. show, social processes are highly path-dependent because what others have done in the past influence what we do in the present", said Peter Hedström [ 4 ], "They offer persuasive evidence in support of one of the core ideas of sociology; namely, that the structure of social action—that is, the pattern and strength of social influence—in and of itself is of considerable importance for explaining the social phenomena we observe".

This study can explain how important an advertisement is and why it takes no effect sometimes. The reported phenomenon is actually a kind of Matthew effects indicated by Robert K. Merton in 1968 [ 5 ]. The difference is the altering extent induced by certain influence. Nevertheless, the interaction process is much complicated which are related to language, history, educated level, past experience...in short, we judge and make decision obeying our deepest instinct—do best as we can and save time or money as much as possible by learning. This is a living religion of ours. ♦