I think the concept of psychology that I am most likely to remember for a while is the wide variety of psychological disorders, vast differences between them, and their prevelance. I've always found disorders to be the most interesting area of psychology, yet I still didn't know as much about it as I thought. The readings gave me an especially good insight into the troubles of some close friends and relatives.
After first hearing of my close friend going through panic attacks, I had little clue what could cause them, nor did I think know how common they were. Reading about it not only gave me information about the problem, it gave me ideas as to how to help my friend through these attacks.
With some of these disorders, such as depression and anxiety, becoming increasingly common, it is important to think about how they are diagnosed, how they can be helped, and what puts a person at risk for them, because one or more could afflict us later in life. And, again, by keeping in mind that these things are common, we can put aside misconceptions and seek the help that is needed.