Coming from a psychology background myself, I would say yes, we definitely underestimate how external factors affect our decision-makings. Peer pressure is one

Coming from a psychology background myself, I would say yes, we definitely underestimate how external factors affect our decision-makings. Peer pressure is one obvious influence, but I would personally say the biggest influences come from factors we're not even aware of. Some I can think of at the top of my head are the way we're influenced by: - our fear of loss - our first impressions (which usually influence all subsequent decisions/habits) - our sense of ownership of an idea/opinion/product - our self-fulfilling expectations (something you expect to be great will usually be great) - and so much more we're usually not aware of For more on the topic, a very readable and engaging book on behavioral-economic influences is Predictably Irrational. At his blog, he shares some of the book's interesting ideas and findings about different factors: http://danariely.com/the-books/ http://danariely.com/the-books/