  In this paper, we consider a mean field model of social behavior where there
are an infinite number of players, each of whom observes a type privately that
represents her preference, and publicly observes a mean field state of types
and actions of the players in the society. The types (and equivalently
preferences) of the players are dynamically evolving. Each player is fully
rational and forward-looking and makes a decision in each round t to buy a
product. She receives a higher utility if the product she bought is aligned
with her current preference and if there is a higher fraction of people who
bought that product (thus a game of strategic complementarity). We show that
for certain parameters when the weight of strategic complementarity is high,
players eventually herd towards one of the actions with probability 1 which is
when each player buys a product irrespective of her preference.
