Before revision:  We find that in the long run, information aggregation fails, and the fraction of private information transmitted goes to zero as the number of agents gets large. With Normal signals, in the long-run, agents learn less from observing the actions of any number of other agents than they learn from seeing three other agents ' signals .
After revision:  With normal signals, a group of any size learns more slowly than just four agents who directly observe each others' private signals in each period. Similar results apply to general signal structures .