  Social learning is defined as the ability of a population to aggregate
information, a process which must crucially depend on the mechanisms of social
interaction. Consumers choosing which product to buy, or voters deciding which
option to take respect to an important issues, typically confront external
signals to the information gathered from their contacts. Received economic
models typically predict that correct social learning occurs in large
populations unless some individuals display unbounded influence. We challenge
this conclusion by showing that an intuitive threshold process of individual
adjustment does not always lead to such social learning. We find, specifically,
that three generic regimes exist. And only in one of them, where the threshold
is within a suitable intermediate range, the population learns the correct
information. In the other two, where the threshold is either too high or too
low, the system either freezes or enters into persistent flux, respectively.
These regimes are generally observed in different social networks (both complex
or regular), but limited interaction is found to promote correct learning by
enlarging the parameter region where it occurs.
