stylistic:style_transfer, quality:corruption
1. Origin of operant behavior

Skinner's answer to the first question was very much like Darwin's answer to the question of the origin of a 'new' bodily structure, namely, variation and selection. Similarly, the behavior of an individual varies from moment to moment; a variation that is followed by reinforcement is strengthened and becomes prominent in that individual's behavioral repertoire. Shaping was Skinner's term for the gradual modification of behavior by the reinforcement of desired variations. Skinner believed that 'superstitious' behavior can arise when a response happens to be followed by reinforcement to which it is actually unrelated.