Facebook appears to have more of an indirect role in shopping than anything statisticians can pin down, but psychologists might see a more direct connection.

Suggestions made through social media have influenced half of all shoppers, according to Facebook storefront maker TabJuice, which put six psychological theories of shopping in a nifty infographic that we’ve reproduced at the bottom of this post.

That said, here are six ways to appeal to people’s psyches to motivate purchases:

1. When people feel insecure about making a decision, they turn to others;
2. The most authoritative of these sources will end up with the strongest influence on a person’s decision;
3. Scarcity of any resource makes it seem more valuable;
4. People want to emulate those that they like;
5. When faced with uncertainty, people tend to make decisions that are consistent with what they’ve done in the past; and
6. People have an innate desire to repay favors from others.

Readers, how do these six principles compare with your own experiences on Facebook?