Research into behavioral economics has shown that our assessment of what something is worth to us can be directly, and predictably, influenced. This is the illusion of the free lunch, something humans are known ＿＿（46）＿＿ even when economic theory would clearly suggest we select a more valuable option at a small cost. Researchers also found how we sometimes operate on social norms, while other times we fall into market norms. The difference is in whether there is a price attached to something. If a friend invites you over for dinner, she will probably appreciate it if you bring a nice bottle of wine along (social norms). However, if instead you throw $20 (the price of a nice bottle of wine) in cash on the table and say "thanks for a lovely dinner," she would most likely ＿＿（47）＿＿ (market norms). Mixing social norms and market norms inappropriately often leads to irrational behavior and, possibly, even to conflict or ＿＿（48）＿＿ . Our irrational behavior is not just random though. The scientific experiments are ＿＿（49）＿＿ . Each time we are faced with a similar situation, we tend to behave in a similarly irrational way. So, next to the bad news that we are not nearly as rational as we might have thought (or hoped), there is also good news in that we can understand and ＿＿（50）＿＿ our irrational behavior, at least to some extent. This, in turn, can help us improve our decision-making and change our behavior for the better.