1) Contrast refers to a negative association between the response rates on the two components of a multiple schedule-as one goes up the other goes down. There are two forms of contrast, positive and negative. Positive contrast occurs when rate of response in an unchanged component of a multiple schedule increases with a decline in behaviour in the other schedule. Negative contrast is defined when rate of response declines on the unaltered schedule and an increase in behaviour occurs in the other component of the multiple.

2) If behaviour has been maintained in two (or more) contexts, and a procedure that decreases behaviour (e.g., DRO, extinction, or punishment) is introduced into one of these contexts, the behaviour may increase in the other, despite no other change in contingencies. This increase is called positive behavioural contrast. behavioural contrast also has been observed when the schedule of reinforcement has been increased in one situation while remaining constant in the other. In this case performance may decrease in the constant situation producing a negative behavioural contrast.

3) There is no definition currently available.

4) The tendency for changes in behaviour outside the training environment to be the opposite of the changes produced in the training environment. (Compare stimulus generalization.)