Focus Constraints

Scott Feld explains the importance of foci in network structure in "The Focused Organization of Social Ties." He explain that ties are not entirely dependent on the existence of a common focus, but that these foci can definitely affect the way we from ties, and the conditions of these foci affect the degree to which we form these ties.
People who are in constant contact and interaction with each other have a particular foci, proximity. This may be a physical proximity, like being neighbors, or a genetic proximity, like being related. My dad, for example, has a few ties that are dependent on the proximity focus. One is our neighbor Dave. He is quite a bit younger and different from my dad, but they have become good friends and depend on each other in many situations because they live across the street from each other. Also, my dad has a strong tie to his cousin Johnny. Johnny always calls him and always needs money, and that annoys my dad. But the genetic tie exists, so my dad always does what he can to help Johnny out.
Another key point made by Feld is that the severity of certain constraints cause pressures to form ties by creating various foci. One common example of this could be kids at a one or two-week summer camp. These kids only have a few weeks to be in contact with the people around them, and therefore actively search for certain common interests to come out of the experience with a friend, whether or not they will continue to see them afterwards. I can remember going to a one-week science-related camp over the summer during middle school at UMass Lowell. I did not know anybody there, and two other kids and I would always play with games like Jenga and others while on our lunch break. I ended up hanging around these kids for the rest of the camp because we found a game to bond over.