What expertise does chef Jamie Oliver have in nutritional science, or education? What about actress and model Jenny McCarthy in the field of epidemiology? Jude Law or George Clooney in international relations? None, by traditional standards of expertise. It's always been earned through professional training and experience. But now, authority is slipping away from 'traditional' experts – and into the hands of celebrities.

It's a simple formula. In a sea of information, products and ideas competing for limited attention, celebrities provide a familiar foothold. Whether or not they have actual expertise in the fields they dabble in, they 

 experts at standing out. And they're natural conduits for making an idea or product stand out, too.

But is it as simple as putting a famous face on a brand? When successful, the formula can yield golden results. Yet there are plenty of examples which caution against assuming it's simple to get right. Not all attention is good, and being an 'expert' in everything can as easily translate into being an expert in nothing. So where does the real authority lie?

Cyber scholar Ethan Zuckerman tells the story of journalists who come up with new units of measurement to explain contemporary phenomena. He uses the example of the 'Jolie' (from actress Angelina Jolie) to measure how global attention affects aid and charity. Zuckerman explains that a Jolie is a “unit that denotes the amount of international aid a country receives when it becomes the 

 of a prominent celebrity.” Darfur, which has received attention from Jolie herself, has received 27 times more aid relief than the DRC, which has not ($300 per capita, as opposed to $11).

Celebrity magazines significantly outsell news publications, even in a recession

Moving away from international aid to attention in general, Zuckerman offers the 'Kardashian'. “Conceptually, the Kardashian is the amount of global attention Kim Kardashian commands across all media over the space of a day”, says Zuckerman. He adds that he chose that specific celebrity because she is an “exemplar of attention disconnected from merit, talent, or reason. The Kardashian mentions how much attention is paid, not how much attention is deserved, so naming the unit after someone who is famous for being famous seems appropriate.” 

We live an attention economy where standing out can translate to money – and paying attention to those who do can have a social and psychological payoff too. People want to buy into a lifestyle – the feeling of proximity to celebrities that comes with buying their products. Celebrities occupy the top rungs of present-day cultural "prestige hierarchies'. Celebrity magazines significantly outsell news publications, even in a recession – and in 2005, 31% of American teenagers believed they would be famous one day. 

Jamie Oliver is an expert chef - but critics point out that he isn't a 'real' expert in education

But how much real authority does fame bring?

 columnist Marina Hyde has identified what she calls the "mission creep" of celebrity culture, whereby fame apparently bestows expertise in a wide range of areas beyond entertainment. 

, the chef addresses a room of professional nutritionists about how to combat childhood obesity. In the Q&A session, one man asks: “Many of us have extensive educations, and a lot of experience. Can you just tell us what makes you uniquely qualified to advise us here?”. Oliver could not give a satisfactory answer. The chef's 

 initiative, in which he recruited celebrities to teach delinquent youths, similarly drew criticism from actual schoolteachers with comments like “What makes him think he has the right to play with children's lives like this?” 

 In this form of 'mission creep', celebrities directly challenge traditional experts like educators and scientists. Whether positive or negative, it can have potentially long-term effects – like Jenny McCarthy infamously advocating against parents immunising their children, believing vaccinations to be a cause of autism.

'Mission creep' can affect brands too. When 'healthy' snack brand Popchips brought on Ashton Kutcher (also an investor in the firm) as their 'president of pop culture', they didn't anticipate the backlash the actor would cause when he impersonated an Indian man in one of their adverts. “Perhaps brownface and offensive accents aren't the best way to sell potato chips”, opened ABC's coverage of the incident. 

 Fortunately for Popchips – and for Kutcher – the company suffered no lasting reputational damage, and remains number 5 on Forbes' list of America's Most Promising Companies. 

 But celebrity chef Paula Deen didn't get off so lightly when she publicly admitted to having used racial slurs, being abruptly dropped by many of her sponsors. 

And while appointing pop star Alicia Keys as the 'global creative director' of BlackBerry did nothing to directly harm the struggling brand (not counting the embarrassment of Keys being seen on numerous occasions with an iPhone), neither did the association have any measurable positive effects, nor prevent job losses and the further decline of stocks. 

Is brand authority undermined without a clear connection with their celebrity endorsers?

Measuring success isn't always straightforward. Jamie Oliver may have received a lot of criticism for his various campaigns, but when asked about his proudest achievement, he could lay claim to “improving the standard of school food, getting £500m put into a service that hadn't been invested in for 30 years and raising the profile of lunch ladies”. 

 And while Oliver is a trained chef, many of the biggest stars in the celebrity chef industry – including Nigella Lawson and Chef of the Decade Heston Blumenthal – have no professional training. 

 In the world of food and drink, at least, expertise can be achieved through unconventional means.

Beats products aren't the best on the market, but they've rocketed to stardom through clever marketing that relies heavily on the celebrity angle

These unconventional achievements are part of the 'rags-to-riches' narrative that many celebrities embody – and professional authorities lack. Unlike the nameless doctor in a lab coat or bureaucrat in a office, fans of Jamie Oliver have watched him grow from his father's pub into the father that he is today. Fans of Kim Kardashian have witnessed her humiliation at her pregnancy weight gain, and her jubilation at her subsequent weight loss. By showing that they, too, are sometimes vulnerable, celebrities have an actual expertise that many professionals lack: garnering the trust of their fans.

Possibly one of the most successful examples of 'mission creep' is audio equipment range Beats by Dre, named after rapper Andre "Dr. Dre" Young. Founded in 2006, the company produces the best-selling headphone on the US market in the above-$100 category. 

 Beats products aren't the best on the market, but they've rocketed to stardom through clever marketing that relies heavily on the celebrity angle – with stars like Katie Holmes, Gwen Stefani and Michael Phelps all publicly using the headphones. 

People perceive less expertise when a celebrity is the face of too many products

It's not a stretch to imagine a musician as an expert on sound quality. Neither is it unreasonable for a chef to take an interest in nutrition, or for a model to contribute to a fashion magazine – as

 took advantage of by hiring Kate Moss as a fashion editor. 'Taking an interest in' is different from 'being an expert on', but as long as there's a clear connection between the celebrity and the product they're endorsing, there'll be a convincing perception of authority.

As much as people like celebrities, they respond better to endorsements that combine logical associations

As much as people like celebrities, they respond better to endorsements that combine logical associations – like a musician who cares about headphones. And they're more likely to buy into the association if the celebrity isn't simultaneously the face of several other products. 

New technology and social media mean people are becoming fickle with where they'll spend their limited attention. Nurturing more meaningful connections could be the way forward – and if a relationship does sour, as with Paula Deen, a panicked public severing of ties could be seen as “little more than a cynical attempt by the company to clean up its image”. 

In short, mimicking the processes of achieving authority – exercising patience and acting on considered decisions – is likely the best way to maintain the currency of expertise. We may have entered an era where people prefer getting advice, tips and tricks from celebrities, but that doesn't mean they've forgotten what being an 'expert' actually means.

is the author of Food Media: Celebrity Chefs and the Politics of Everyday Interference (2012) and Food and Social Media: You Are What You Tweet (2012). When not keeping a close eye on Jamie Oliver, Dr Rousseau teaches critical literacy at the University of Cape Town.

'Guestlist branding: how Samsung tapped marketing's Holy Grail'

'Real emotion: the rise of reality culture'

 - People are increasingly information and stimulus rich but consequently time and attention poor.

 - Consumer distrust has caused the authority figure to return to a position of influence.

 - Consumers seek honest brands with an authentic mission and an engaging personality.

Advertising

Behavioural sciences

Psychology

'An idea worth at least 40 nanoKardashians of your attention', My Heart's in Accra

'Celebrity Magazines Post a Downturn in Sales', The New York Times

'Ethics of Celebrities and Their Increasing Influence in 21st Century Society', Journal of Business Ethics

'Celebrity: How Entertainers Took Over the World and Why We Need an Exit Strategy', Marina Hyde

'Is Jamie's Dream School a success?', The Guardian

'Ashton Kutcher's Popchips Ad Pulled After Racism Outcry', ABC

'Popchips', Forbes

'Paula Deen Dumped By Home Depot and Diabetes Drug Novo Nordisk As Target, Sears, QVC Mull Next Move', Forbes

'Blackberry Spokeswoman Alica Keys Blames iPhone Tweet on Drake-Obsessed Hacker', Slate

'BlackBerry Job Cuts: Smartphone Maker To Lay Off 4,500', The Huffington Post

'Jamie Oliver: I cause a storm every time I open my mouth', The Observer

'OFM awards 2013 chef of the decade: Heston Blumenthal', The Observer

'Celebrity-Obsessed Culture Has Overtaken Marketing', Ad Age

'Beats by Dre: Best Headphones or Best Marketing', Viewpoints

'When Exclusivity is Crucial for Celebrity Endorsements', strategy + business

'When Good Celebrity Endorsers Go Bad, Markets Get Angry (But Not for Long)', strategy + business

Authority is slipping away from 'traditional' experts – and into the hands of celebrities. But is 'standing out' from a sea of information, products and ideas as simple as putting a famous face on a brand?