The academic term for this area of economic study is Marginal Propensity to Consume[1]. It's defined as:

  "The proportion of an aggregate raise in pay that a 
  consumer spends on the consumption of goods and 
  services, as opposed to saving it."

I don't think it's very controversial.

[1] http://en.wikipedia.org/wiki/Marginal_propensity_to_consume