The Law of Effect (also known as reinforcement) states that the consumer‘s probability of repeating purchase of a brand would increase if he/she were satisfied with the purchase and decrease if dissatisfied.
Note: Law of Effect is a technical term from learning theory in psychology often credited to Edward Thorndike. Of the several responses made to the same situation, that which is accompanied or closely followed by satisfaction, other things being equal, will more likely be repeated, and the connections learned. Those responses that are followed by punishment will be extinguished. However, whether rewards and punishment are essential for learning to occur is controversial in that many learning theorists claim that reinforcement is unnecessary. 
- American Marketing Association, AMA Dictionary.