Attachment Theory

Attachment Theory is one of the most researched psychological theories. Here is a basic overview of the attachment styles (secure, anxious, avoidant) that most people seem to fall in to. Interestingly, there's a strong correlation between our style as children and as adults. Keep in mind that while humans love to categorize, in real life these styles are more complex than they're laid out here, and they can change from relationship to relationship..

What Emotions Are (And Aren't)

It seems intuitive in a way, but Lisa Feldman Barrett, a psychology professor at Northwestern, explains in this New York Times article why emotions are a lot more complex than we thought: