Motivation to expend effort is shaped partly by how reinforcement is scheduled. In particular, motivation tends to be higher if reinforcement occurs at random rather than fixed intervals. Hence, we are highly motivated to constantly check email because the reinforcement of a new message comes at random times; if it came at fixed points, motivation would be lower.
It's all over Facebook! Repeated exposure to an idea can make it seem more familiar, which in turn increases the chances of us believing that it is also true. This can be dangerous in an environment where we may find ourselves perpetually exposed to new information through invalidated sources (Facebook, Twitter, etc.).
Habits, habits, habits! Habits are patterns of behavior that are repeated regularly. Their occurrence tends to be subconscious, and they can become powerfully entrenched as determinants of behavioral decision making, over and above current goals and values. Habit loops form through the relationships between cues, routines, and rewards.
OBVIOUSLY! Once we know about something, it is difficult to imagine not knowing it. This can make it very challenging to communicate ideas that we are intricately familiar with others, because we can’t conceptualize the topic from their point of view.
Accents and languages are an intriguing manifestation of this phenomenon. If you’ve ever experienced the clarity of a mispronounced word while you are trying to teach someone a language that is foreign to them, and they had no clue what your subtle correction meant, you have experienced the curse of knowledge.