1. principle of reciprocity - individuals tend to reciprocate; if someone
does something for you (such as, lowering the price of their product), then
you feel more obligated to do something for them (like buy the product).
2. principle of commitment - if you make a small commitment, then you
will be more likely to commit to something larger in the future (e.g., just
buy a single book, then you'll be more likely to buy all the other books that
the Time/Life company will regularly send you).
3. principle of scarcity - individuals dislike feeling that they can't
have something; thus, people desire the scarce object more (e.g., "limited
edition," only so many will be made).
4. principle of conformity or consensus - if everybody has one, then
I need it too (e.g., "This is the fastest growing or most popular product
in the country").
5. principle of authority - individuals are more likely to comply (i.e.,
buy a product) if an "authority" endorses the product. The "authority"
can be an actual authority figure, such as a medical doctor endorsing a vitamin
supplement, or the "authority" can simply be someone who is popular
or respected (e.g., a celebrity endorsing a product).
6. principle of liking - individuals are more likely to buy a product from someone they like (e.g., a friend or relative having a Tupperware party, or people being more likely to buy a product from people who are similar to themselves).