Disclaimer. Don't rely on these old notes in lieu of reading the literature, but they can jog your memory. As a grad student long ago, my peers and I collaborated to write and exchange summaries of political science research. I posted them to a wiki-style website. "Wikisum" is now dead but archived here. I cannot vouch for these notes' accuracy, nor can I say who wrote them.
Hansen. 1985. The political economy of group membership. APSR 79:79-86.
Despite Olson's claims, people do join groups primarily for the political (collective) goods they pursue. Though are are no sufficient conditions for interest group formation and maintenance, there are however a "host of necessary--and highly contingent--conditions" (p94).
When he says "political benefits," he means "collective goods."
Olson to the contrary, these do matter. Drawing on prospect theory (we're willing to risk a small loss to avoid a larger loss), Hanson argues that we will join a group if an existing political benefit appears threatened (e.g. if we already have farm subsidies but they are threatened, I join the Farm Bureau). Thus, although there is risk involved in joining a group (a risk that others won't join, thus my dues will be spent but I won't get the collective good), I am willing to accept this risk if it gives me the chance to avoid a threat.
These have varying elasticity. Some, like insurance, are inelastic. Others, like journals and expressive benefits, are elastic. Thus, we join when times are good (we have more money for elastic goods).
Of course, income matters in how we can handle costs. But in addition to that, we perceive costs in relation to what else we could be having. Thus, if there are other groups competing for out loyalty, the opportunity costs of joining a particular group rise. Thus, Hanson expects to see fewer people joining groups when there are multiple groups trying to provide the same benefits.
These expected costs and benefits don't enter into the equation only according to their raw values--our information about each one matters. If we hear a lot about threats to existing benefits from the media, we will join to protected our political benefits (collective goods) because we perceive the threat more intensely than we perceive the other parts of the equation.
He looks at the Farm Bureau, the League of Women's Voters, and the Home Builders. He finds that
For their ORIGINS, interest groups depend on outside subsidies. Originally, producer's groups (and later labor) because they received outside subsidies from firms (in the case of producers) and the government (in both cases, especially during WWI). Later, as foundations came into being, they were able to provide outside subsidies for consumer and environmental groups. Political entrepreneur also matter. For them, there is a "Say's law" for interest groups: supply creates its own demand.
We join organizations for one of three purposes. In any of these three cases, political benefits are absolutely a necessary part of the decision. They aren't marginal (as in Olson's by-product theory), but are central to our decision:
Research on similar subjects