What is Pair by association?

In relation to psychology, pair by association is the action of associating a stimulus with an arbitrary idea or object, eliciting a response, usually emotional. This is done by repeatedly pairing the stimulus with the arbitrary object.

For example, repeatedly pairing images of beautiful women in bathing suits elicits a sexual response in most men. Advertising agencies repeatedly pair products with attractive women in television commercials with the intention of eliciting an emotional or sexually aroused response in the consumer. This causes the consumer to be more likely to buy the product than when presented with a similar product without such an association.