What is the field that studies community responses to incentives? Having recently read Freakonomics I was particularly interested by the idea of the responses of a community to incentives - as an example, the tale of a school which tried to introduce a financial penalty for picking up children late, which inadvertently had the opposite effect, as it nullified the previously existing (but largely invisible) social penalty.

Is there a general theory for this kind of interaction of incentives with community? If so, what is its name, and where could I read more about it? I'm interested in books and papers on a variety of levels, from popular accounts (à la Freakonomics) to textbooks to research papers.
There is a specific field of economics that deals with the process of changing people's responses through incentives: Behavioural Economics.


  study the effects of social, cognitive and emotional factors on the
  economic decisions of individuals and institutions and the
  consequences for market prices, returns and the resource allocation.


A recent issue of The Economist covers some of the current approaches used by governments to change individual behaviour:


  Behavioural economists have found that all sorts of psychological or
  neurological biases cause people to make choices that seem contrary to
  their best interests. The idea of nudging is based on research that
  shows it is possible to steer people towards better decisions by
  presenting choices in different ways.


Some of the approaches, for instance used by the British Behavioural Insights Team, are merely ways of changing a message:


  The Nudge Unit has been running dozens of experiments and the early
  results have been promising*. In one trial, a letter sent to
  non-payers of vehicle taxes was changed to use plainer English, along
  the line of “pay your tax or lose your car”. In some cases the letter
  was further personalised by including a photo of the car in question.
  The rewritten letter alone doubled the number of people paying the
  tax; the rewrite with the photo tripled it.


It's become a very fruitful area of research so would recommend taking your interest further.