I like to run a few times a week to get some exercise. I have a few routes through my neighborhood, and that has given me the chance to observe the pattern of proliferation of political yard signs. Austin leans Democaratic, and so the Obama signs outnumber the McCain signs. However, what is more interesting to me is that the signs tend to clump together. There will be a block with very few signs, and then suddenly a cluster of houses, each of which has a sign.
Now, if those signs were all for one candidate or one party, you could argue that there was someone in one of those houses who supplied signs to all of the neighbors. As likely as not, though, the signs will reflect different party allegiances. There will be a few houses with Obama signs next to a few houses with McCain signs.
One explanation for this clumping is goal contagion. A remarkable facet of human beings relative to all other animals is that we tend to look at other people's behavior and see not only what they are doing but what they are trying to accomplish. That is, we automatically interpret the goals that people have from their behaviors. Mike Tomasello (whose work I talked about in the blog entry on cooperation) has argued that this ability to reason about other people's goals has been crucial for the development of complex culture.
In addition, because we reason about other people's goals, we are often driven to adopt those goals ourselves. Henk Aarts, Peter Gollwitzer, and Ran Hassin have a paper in the Journal of Personality and Social Psychology in 2004 in which they had people read stories about other people who were pursuing particular goals. For example, they might read about people who were flirting with other possible romantic partners. After reading these stories, people were put in situations where they could participate in the same goal. For example, they could help either a female or a male research assistant clean up a spill. Men who read about flirting where more likely to help the female research assistant than were men who read other stories.
So, when someone puts out a yard sign, they are announcing their preference for a political candidate to the world. This action leads others who see it to be more likely to want to announce their own preference. This desire is likely to be particularly strong for neighbors of the individual with the yard sign, because those neighbors will see the sign ever day.
To my mind, this effect is a positive one. It is crucial for people to care about the political process. One way to get people to care about this process is for others to perform actions that show they care. Those individuals who put out the first sign are performing an action that can lead others to participate in the political process.
