  We consider the herding to non-herding transition caused by idiosyncratic
choices or imperfect imitation in the context of the Kirman Model for financial
markets, or equivalently the Noisy Voter Model for opinion formation. In these
original models this is a finite size transition that disappears for a large
number of agents. We show how the introduction of two different mechanisms make
this transition robust and well defined. A first mechanism is nonlinear
interactions among agents taking into account the nonlinear effect of local
majorities. The second one is aging, so that the longer an agent has been in a
given state the more reluctant she becomes to change state.
