Liking (friendship, attractiveness)

"The source credibility of sales people affects their ability to influence customers. Source credibility is enhanced by increasing perceived expertise, trustworthiness and attractiveness."
- Pederson, Wright, Weitz (1984)

"Relationship Building

The relationship between pharmaceutical representative and prescriber is all-important to increasing sales. Representatives do whatever it takes to increase their "face time," because developing a relationship is frequently the first step in developing credibility. In the initial training of a pharmaceutical representative, more emphasis is placed on developing general verbal communication skills and specific communication with physicians than is placed on product knowledge...

One of the most frequent and easiest ways to create a relationship is by the giving of gifts."
- Shaughnessy et al (1994)

Pederson, Wright, Weitz. Selling: principles and methods. 8^th Ed. Homewood, Illinois. Irwin 1984
Shaughnessy AF, Slawson DC, Bennett JH. Separating the wheat from the chaff: identifying fallacies in pharmaceutical promotion. J Gen Intern Med 1994;9:563-8.