Robert Cialdini is an expert in the field of influence and persuasion. His contribution to the study of successful sales and marketing tactics is well recognized.
Cialdini provides a framework outlining why people are influenced to behave in a certain manner.
If you have done sales or marketing for any length of time, I am sure you will recognize the truth in his fascinating findings, which I have listed below.
6 key principles of persuasion
Insofar as free samples, a fascinating insight: the scientific observation that free samples can often "cheapen" the value of the product they are intended to sell. In other words, if the product is not of value enough to sell on it's own merit, there must be a reason, IE others don't want it. Subliminally, this indicates that since others don't want it there must be a problem with it, and if others don't want it the product must be undesirable.
It's a play on the principles of "social proof", outlined below, and it's also an interesting twist on the "scarcity" angle. And, it has significant implications for those making pricing decisions, namely that reducing the price may not always lead to improved sales. Reducing the price indicates to the public that a product is not in demand and is therefore not socially desirable, and can in fact hurt sales.
Golden quotes: "consistency is the last refuge of the unimaginative", and "the best way to ride a horse is in the direction it is going". In other words, don't try to change a stubborn personality all at once; get into their thinking and "steer" them in the direction you want to take them.