If one wishes to study the effect of advertising, a concise definition of the concept of advertising is essential. In business-circles, the function of advertising is often defined: advertising must sell. Although it cannot be said that this definition is incorrect, it is certainly inadequate. Quality, presentation, distribution, merchandising, etc, should also be of a kind that stimulate sales. This particular definition therefore does not adequately describe the concept of advertising. Advertising should influence the attitude of the consumer towards a product or service in such a manner, that he is not only favourably influenced with regard to such a product, but also wants to acquire it. A very attractive definition, which in turn provides the market researcher with a workable framework, is Martin Mayers: "Advertising, in addition to its purely informative /unction, adds a new value to the existing values of the product or service". The merit of this definition is that its elements not only give an almost complete description of the task of advertising but the terminology used also defines exactly the scope of its field of activity.