Invisible Influence by Jonah Berger

one world should be popular in all of them. If 52 Metro’s “Lockdown” was the most downloaded song in one world, it should be close to the top of the list in others. On average, preferences across the groups should be the same.
    But they weren’t.
    Song popularity varied widely from one world to the next. 52 Metro’s “Lockdown” was the most popular song in one world. In another, one of the least popular. Fortieth out of forty-eight. Almost dead last.
    Same song, indistinguishable groups of participants, completely different levels of success. Same initial conditions, different final outcomes.
    Why was success so variable?
    The reason was social influence. There weren’t more punklovers in the world where 52 Metro was popular than in the world where it wasn’t. But because people tend to follow those who came before them, small, random initial differences snowballed.
    To understand why this phenomenon occurs, imagine parking at a county fair. There’s no real parking lot per se, or even someone directing traffic, just a big field where people leave their cars. People are generally indifferent about where they park, they just want to go eat cotton candy and ride the Ferris wheel. There are no white lines denoting where individual cars should go, so the first family that drives in can park wherever they want.
    The first car that drives up happens to be driven by the West family. They slightly prefer facing west when they park, so they drive in, turn right, and park their car facing west:

    Then the second family shows up. This family, the Souths, prefer parking facing south rather than west. But their preference is not that strong, and given that the first car is parked facing west, they pull up next to them and face west as well:

    Soon, more and more cars show up. While the people in each might have a slight preference here and there, they follow the cars ahead of them until the parking lot ends up looking like this:

    Makes perfect sense.
    But what if, rather than the West family showing up first, the South family had shown up first instead? What if the Souths had been the first to park in the lot?
    Instead of parking facing west, given the Souths’ slight preference for facing south, they go ahead and park that way:

    The Wests show up next. They would have slightly preferred to face west, but given a car is already facing south, they go ahead and do the same. More and more cars show up, all following the cars in front of them, until the lot ends up looking like this:

    Same eight cars, same overall parking preferences of people in the lot, but completely different outcome. Everyone is facing south rather than west. Just because of the preferences of whoever happened to park first.
    This same process drove the outcome of the music study. Imagine two of the social influence worlds at the start of the experiment. They are essentially identical. None of the songs have any downloads. Even the participants are the same, on average.
    Just like the Wests and the Souths, though, different individuals may have slightly different preferences. One person may have a slight preference for punk over rap, while another has a slight preference for rap over punk.
    And the order in which these two people express their preferences varies. In one world, the person who likes punk happens to go first. They listen to a few songs, find a punk song they like, and download it. Score one for the punk song, zero for the rap song. Then, when the second listener comes along, they use the first listeners’ choice as a guide. The punk song has more downloads, so it gets more attention. The second listener has a slight preference for rap, but they like punk and the song seems pretty good, so they download it. Punk 2, Rap 0.
    In the other world, the person who prefers rap happens to go first. The process is much the same, but with a different outcome. They listen to a few songs, find a rap song they like,