We study observational learning in environments with congestion costs: an agent's payoff from choosing an action decreases as more predecessors choose that action. Herds cannot occur if congestion on every action can get so large that an agent prefers a different action regardless of his beliefs...

We study observational learning in environments with congestion costs: as more of one's predecessors choose an action, the payoff from choosing that action decreases. If congestion on either action can get so large that an agent would prefer to take the other action no matter his beliefs about...