I'm a celebrity. What do you want to hear?

Celebrity endorsement has been a part of advertising since the first advertising agent thought "This will sell if we get someone famous to say they like it". It relies on the halo effect, where success or skill at one thing is assumed to transfer to some other thing. It's perfectly acceptable when the celebrity has some relationship to the product through what they are famous for, like tennis stars endorsing racquets and shoes or motor racing drivers telling us that some company makes the best tyres in the world. People quite rightly assume that the celebrities are being paid to say what they say, and again there is nothing much wrong with that.

Sometimes the product can eclipse whatever it is that the celebrity is famous for, and I would expect that many people of a certain age could easily tell you what brand of cigarettes actor Stuart Wagstaff smoked but would have great difficulty naming any theatre, film or television production that he had appeared in. (The cigarette company continued to pay him for 17 years after cigarette advertising was banned on Australian television, because they believed that his identification with the brand was enough to bring it into people's minds.)

A series of advertisements currently running on television feature a very well-known actor telling us how a medical device "may assist" in relieving certain conditions. The ads have recently been updated with a small overlay reinforcing the fact that these things might not work and also adding in very small print that the actor is being paid to say the words. Interestingly, the previous celebrities promoting this product had been very successful sports people whose views on such a device might carry some weight but the immediate past endorser is now telling us where to buy cheap solar panels, something which has little if anything to do with what he was very good at before he retired.

Apart from the cigarette advertising, most celebrity endorsement is pretty harmless but it can become a problem when the celebrity decides unilaterally to use their fame to push a personal belief or ideology. I'm going to look at two examples.

Actress Jenny McCarthy had appeared in some less than memorable movies and television shows but was generally usually referred to as a former Playboy model, something which she did in the early 1990s. She suddenly reinvented herself as a spokesperson for the anti-vaccination movement, dragging her then partner actor Jim Carrey along to increase celebrity quotient. She of course claimed that she was not opposed to vaccines, but they all say that.

Her fame gave her access to high rated television shows like the Oprah Winfrey Show and some high circulation print publications, and these platforms allowed her to spread misinformation very widely. The problem with countering this misinformation was that it could be easily construed as attacking the mother of an autistic child. Unfortunately much of the pushback against her involved describing her as a "Playboy nude model", although what she had done 20 years previously was irrelevant. The real problem was that what she was saying was not based on science or fact, but this has always been a problem when countering the nonsense coming from alternative medicine or anti-vaccination campaigners. (Or any other form of scientific nonsense. Science is hard and boring and often disagrees with what we think we are experiencing or feeling.)

McCarthy's anti-vaccination activities did enormous damage, and that damage was largely based on people believing what she said simply because she was famous.

The other example is Australian "celebrity chef" Pete Evans. As host for a decade of one of the country's most highly rated television programs, a program all about food and cooking, what he has to say about food could be given a lot of weight. His main claim to fame in this area is promoting what is called the "Paleo Diet", where to achieve and maintain health we should eat the foods that they did back before agriculture and cooking were invented. The idea that Stone Age people were healthier than people are today is of course a total myth, but it can sell a lot of books. (I'm reminded of this wonderful cartoon from a few years ago.)

Evans has had one book he wrote about baby diets withdrawn from sale because the publishers were convinced that the advice in it was dangerous, but generally his diet advice is a combination of uselessness, inconvenience and expense. Very unfortunately, he now appears to have climbed onto the anti-vaccination bandwagon where he can do some real damage.

Celebrity endorsement isn't going to go away but like all recommendations it needs the application of critical thought, and how to get people to do that will remain a problem for a long time.

This article was published as the Naked Skeptic column in the May/June 2019 edition of Australasian Science

See more from the late Randy Glasbergen here