Reinforcement is the process of increasing or decreasing the weightings or parameters that gave rise to a positive or negative behaviour. The idea is based on Skinner's experiments with pigeons in the 1950s. If the mapoing between stimulus, behaviour and reward is simple and direct, for example a look-up table with weights, then reinforcement is relatuveky straughtfirward. More commonly however, the causal relatiinship is complex and there are problems of credit assignment.
Used on Chap. 22: page 546