Final answer:
Researchers describe the effect celebrities have on our attitudes as 'celebrity endorsement,' where credible and attractive celebrities persuade the public, triggering associative learning and influencing their purchasing decisions.
Step-by-step explanation:
The impact of celebrity endorsement.
The influence that celebrities have on our attitudes and behaviors, as described by Julius's scenario of wanting a shirt worn by his favorite actor, is often termed as the impact of celebrity endorsement. Researchers in social psychology refer to this phenomenon as the use of a credible, attractive source to persuade or condition the public attitude towards a product.
Celebrities are seen as persuasive because they are perceived as trustworthy and desirable, with their endorsement triggering an associative learning process where products are linked with positive attributes. This method of advertising is based on the combination of an affective response (our feelings towards the celebrity), a behavioral response (the desire to emulate or affiliate with the celebrity by purchasing the product), and a cognitive response (beliefs and knowledge about the celebrity and product).