Testimonials by celebrities "are below average in their ability to change brand preference. Viewers guess the celebrity has been bought, and they are right…. Viewers have a way of remembering the celebrity while forgetting the product," quoth David Ogilvy in Ogilvy on Advertising (1983).

Much ink has been spilt over the in/efficacy of using celebrities in ads. Even David Ogilvy, "the father of advertising," did not spare the issue a good whipping. From Kapil Dev's Palmolive ka jawab nahin in the eighties down to Shah Rukh Khan's recent endorsement of Nokia - almost all the ads on TV, radio, print and the internet are accompanied by the physical presence or voice of some celeb. It is also true that we all liked the Palmolive ad and of course still remember it in spite of Palmolive no longer being the only lajawab shaving cream brand in the market. Indeed, advertising is just as competitive as the business of selling a product or service.

But one thing is sure - that a memorable ad has the power to render a product memorable by making it a generic byword for all products in its category. As asianmarketresearch.com says, "The first recalled brand name (often called 'top of mind') has a distinct competitive advantage in brand space, as it has the first chance of evaluation for purchase." The "Got milk?" campaign in the US that put life back into milk sales nationwide after a 20-year slump, the Dhoondte rahe jayoge ad of HLL's Surf Excel that was meant to be an entertaining rejoinder to P&G's Ariel, the "Sunil Babu" ad of Asian Paints - are examples of memorable commercials that definitely aid in the brand recall. But how many of us can recall the ads (if there were any) of Ariel and Berger from that period? Too few, I am sure.

Moreover, in view of Forrester Research's recent report that ad agencies of today are not well-structured to tackle tomorrow's marketing challenges and that consumers increasingly do not trust marketing messages, this old "effectiveness" debate between celeb ads and non-celeb ads ultimately boils down to the debate between ads and no-ads.

The difference between a celebrity and a non-celebrity is obvious. A celebrity is a person who is publicly recognised and who uses that recognition to further the goals of marketers by appearing in advertisements directed at consumers. Similarly, a non-celebrity is a person who, prior to placement in the campaign, has no public recognition but appears in an advertisement for the product.

Network 18 Group's network creative director Zubin Driver places importance on the script of an ad. He says, "The effectiveness of an ad depends on the script. I think it's a creative mistake to use a celebrity when the script is weak. There's also the question of execution - how the idea behind the whole project is being executed. A good idea, coupled with an original script and good execution, makes all the difference." He adds, "There should always be an association between the image of the endorser and the product/service being endorsed. These days, celebs are being overexposed in ads. People are being confused and bored."

For an ad with a non-celebrity spokesperson, credibility is highly correlated to advertising authenticity, which is in turn correlated to purchase intentions. For example, we can take a recent Canara Bank TVC where a middle-aged South Indian lady learns Punjabi to welcome her son's Punjabi fiancé into the family. Capturing every detail and nuance of a Kannada household, the TVC lends believability to the locale and situation. In other words, the ad makes viewers feel "at home".

However, researchers also found that under high-involvement conditions, arguments but not celebrities influence attitudes, whereas under low-involvement conditions, celebrities but not arguments influence attitudes. This suggests that celebrity influence may be related to the nature of the product rather than the person.

Since celeb ads are expensive, the question arises whether such ads pay in the long run. It is relevant to note here that according to media reports, Shah Rukh Khan's "income from endorsements fetches him Rs 1.5 billion ($38 million) a year, the highest for any Indian advertising 'model'."

Driver agrees and adds, "Like celebs, cricket is also being overexposed and overused. Everyone's trying to cash in on the popularity of cricket. As I said earlier, without an original idea, cricket as a background in ads doesn't work."

According to Ogilvy & Mather's executive creative director Abhijit Avasthi, it is wrong to say that celebrity advertising is a shortcut method but certainly not a creative way to reach out and better brand recall.

"I've worked with Abhishek Bachchan in the Motorola ad, which is a very successful ad. If a strong idea is executed well, celeb ads definitely work," he says.

It is also true that celebrity endorsements in India and abroad are different. In the west, celebs endorse brands that are associated with their image, fun, sports, etc. One remembers St John's ad with Angelina Jolie, Louis Vuitton ads with Catherine Deneuve and Scarlett Johansson, and the ads of VISA featuring Pierce "Bond" Brosnan.

Avasthi says, "I don't think that there should necessarily be an association between the celeb's image and the product being endorsed."

But is Amitabh Bachchan in a Reid & Taylor ad just as effective as Amitabh Bachchan in a Navratna oil ad?

Avasthi defends, "Celeb ads of lifestyle products are always effective because of the presence of the celebs. People tend to use such products. The celeb factor may not be a necessary component of the ad - his/her presence may be natural. Amitabh Bachchan is one of the greatest actors of our time. Since an ad is like a film, having Mr Bachchan act in an ad pays doubly."

Indeed, people can relate to the celebrities very easily. They talk about Amitabh Bachchan and Shah Rukh Khan in such a way as though they were members of their family. They know about the celebrities more than their own close relatives!

There is also the matter of trust. If one sees an unknown face in a commercial for a new product he or she will not be buying it very easily unless the person concerned is an early adapter and is obsessed with that product. On the contrary, if a person sees some known face with whom he can easily relate, the trust will come automatically.

For sure, in the successful "Got milk?" campaign, believability, knowledge, appearance and liking for the celebrity were highly correlated to each other and also with purchase intentions.

Thus, an ad has to bring in the right person for the product. If Aishwarya Rai is made to advertise for some sport material that ad will not be as successful as those projecting her as a beauty icon.

As McCann-Erickson's regional creative director (South & South-East Asia) Prasoon Joshi says elsewhere, "Celebs should be used as messengers, not the message."