While watching TV, Yara and her friend Sophie see an advertisement of a new shampoo. While Yara tells Sophie that she intends to buy the product, Sophie, who is a dermatologist, warns her that the shampoo has harsh chemicals that could be harmful to the scalp and hair. After hearing this, Yara decides not to buy the shampoo. Over the next few months, the advertisement is often played on TV. Yara forgets Sophie's warning and buys the shampoo. This is an example of .

The answer is the sleeper effect.

Explanation:

The sleeper effect is usually related to persuasion. It occurs when there is a delay in the effect of a message. When there is a persuasive message like a television advertisement, people's attitudes usually increase.

Over time, however, some attitudes change the way through which people perceive the message. It means that it seems that people had never been exposed to communication. Furthermore, the sleeper effect occurs when people are exposed to a specific persuasive message, and at the same time, this persuasive message is followed by a discounting cue.