So I came up with this metaphor that I think describes the instincts pretty well. Note this is a supplement to more in depth descriptions.
Imagine a spider web (don't run away please!). A giant spider web. With lots of spiders. Something like this (not for the arachnophobic).
Anyway, each of those spiders represents a person. Each strand on the web connects a person to all other people that person knows. And the web as a whole represents society.
Insert instincts here:
Social types want to be connected to the web as a whole and know what's happening on a macro level.
Sexual types want to maintain and strengthen the individual bonds between two people. They want to know what's happening on a micro level.
Self Preservation types want to tend to and take care of the people. Making sure they're safe, secure and healthy. They care about what's happening on a personal/individual level.
Each type serves a role in the web. So types make sure that each spider is and there are no gaping holes. Sx types make sure that each individual strand is secure, and Sp types make sure that each individual spider is healthy and comfortable.