This is defined as the extent to which the learner can issue a behavior that is functionally equal to the behavior that was taught, it is said to be response to similar stimuli that produces a similar effect.
The other responses to which response generalization spreads need not bear physical or topographical similarity to the reinforced operant. The other responses that are strengthened in response generalization are typically members of the same operant response class; an operant response class is a grouping of operants that share a common function.