Is confidence a placebo effect, and can it aid in overcoming tough spots?

I want to elaborate on something that had been bouncing around my head for a few days, and would love to get multiple perspectives on this.
http://beatboxworld.com/online-roulette.html

Poker is about making better decisions than your opponent(s). The difficulty of the game is directly proportional with the level of difficulty of your decisions. Therefore, spots where you are unsure of the best course of action are spots that you need to avoid.

Planning is probably the best defense against tough spots. Before acting, have a plan of action for every variable. If he calls, I do x. If he raises I do y. That way you're not surprised by anything and you feel more confident in your next decision. (I feel it's somewhat of a placebo effect, but confidence can cause better decisions by itself, so it's valuable imo.)

Some people believe that avoiding tough spots stints your growth, but I feel that the possible growth as a player is outweighed by the cut of your immediate winrate. They also argue that the equity you lose when you're ahead in one of said spots is significant. I disagree here as well because you're acting without confidence, adequate information, and mostly on a complete guess.

I'm sure this thread will be compared to the "waiting for a better spot thread," but I want more insight on confidence and the apparent placebo effect than on avoiding/taking tough spots. Although all insight/perspectives are encouraged.