by Robert Cialdini is an interesting book. It talks about how we are all subject to basic human psychological pressures. The wikipedia entry on Cialdini summarizes the result pretty well: here is my one-liner summary:
- Reciprocation. Tactics used: unequal exchanges (free samples), rejection then retreat (propose an extreme position then retreat).
- Commitment and consistency. Tactics used: induce a small commitment to a particular image (ask for help with some trivial task).
- Social proof. Tactics used: create illusory consensus ("man-on-the-street" endosrements).
- Liking. Tactics used: good-looking salespeople, compliments, mirroring, sell through friends (Amway).
- Authority. Tactics used: false titles (ads from authority figures without expertise).
- Scarcity. Tactics used: time pressure, create false competition.