Psyche behind the sell: the psychiatrist Dr Raj Persaud invites three disorderly and undisciplined personalities (sorry, that should read creative directors) on to the analyst's couch.

In the early 50s, when psychology first became the buzz technique in advertising, the idea was that all advertising had to do was to get people to associate products with safety, sustenance or sex, because these were the three basic human needs. But if your need for food, family and f ... are basically satisfied, as these generally are in our wealthy 21st century society, the question then becomes what then do people want.

In fact, advertising really comes into its own when basic needs are already met, and so are not a distraction. Then people are receptive to discovering, through advertising, what else they want.

What is interesting about Trevor ...