Consumer's problem often reduces to maximize utility's representation. If we choose an individual and a period of time, ceteris paribus,preferences structure is given. We want to treat larger setting and we are interested in solving the consumer problem for two classes of models:
1.preferences of individuals are interdependent, that is the pre-ordering the consumption set of an individual depends on the pre-ordering of other ones and viceversa,
2.preferences of one individual are endogenous with respect to time:we can consider one consumer and suppose that his present preferences depend on his past preferences.
Interdependence can be described in terms of reference groups and full information. Of course conformism and snobberry are exogenously defined (Leibenstein,1950;Hayakawa and Venieris,1977).
Conversely pools which conform to one single choice can be endogenously produced by the model:a pooling equilibrium in a signaling game (Bernheim,1994) or an informational cascade (Birkhehandahi,Hirshleifer and Welch,1992)belong to this class of conformism.
Notice also that in the first class time is given,while in the second class agent is given. It is possible to consider more complicate set-up where preferences are interdependent (between agents) and endogenous.