David Beckham's endorsement deals include Gillette and Adidas

Research by the University of Bath and University of St Gallen, Switzerland, found "keeping up with the Joneses" was people's main motivation when shopping.

Only one in five students who were shown two magazine adverts favoured the fictitious, celebrity-endorsed one.

The advert featuring a fictional student influenced 56% of people asked.

Good impression

It showed a student saying he found the digital camera "hot" and that it was his "preferred" choice.

When questioned, the students who said they bought products to impress others were much more likely to be influenced by the student testimonial and less by the celebrity. This applied equally to men as to women.

The students were also assessed on how important it was for them that the products they buy made a good impression on others.

Catherine Zeta Jones has also been the face of Elizabeth Arden

Professor Brett Martin, of the University of Bath, said: "Our research questions whether celebrities are the best way to sell products. Celebrities can be effective but we found that many people were more convinced by an endorsement from a fictional fellow student.

"This is because many people feel a need to keep up with the Joneses when they buy.

"They like to make sure their product is fashionable and trendy among people who resemble them, rather than approved by celebrities like David Beckham, Brad Pitt or Scarlett Johansson.

"So they are more influenced by an endorsement from an ordinary person like them."