What are the limits of language with respect to communicating the actual reasons that go in making a decision? Simon Sinek in his book 'Start With Why' claims how the brain might fail to communicate the actual reasons behind a made decision and instead at best rationalize it in retrospect (post hoc), due to the logic-emotion dichotomy (rational thought is a product of the neocortex while emotional weight which might have a greater role in decision-making, comes from the limbic system). I want to know more on this and other related limits as applicable (of course, assuming their existence has been scientifically proven or at least speculated). Book recommendations are being specifically asked for.
Perhaps oxytocin can be associated with Sinek's why. I think this article can be helpful:
Oxytocin and the Biopsychology of Performance in Team Sports

From the discussion:


  The ability to perceive and understand the mental state of others is very important for an athlete in a sport and especially so in a team setting where working together toward common goals is key. Athletes have to infer internal states in order to make sense of or predict a teammate or opponent’s behavior.


Simon Sinek describes the process of finding a common thread in all your actions. He calls this "your why". Sinek states that the why is an unconscious part of your mind. The why is discovered by searching for patterns in situations where you feel motivated. A slogan-like phrase should then be developed in order to represent the why. The purpose of the phrase is to enable you to be conscious about the motivational drive. You should use the phrase as a guide in order to make your life more meaningful. Even though Sinek talks a lot about "finding your why", then he doesn't talk much about techniques of applying it. I think that the why-phrase can be used in a couple of ways:


As a guideline in making new decisions.
As a tool for unconscious focusing through priming. This is the main function of slogans: The Psychology of a Smart Slogan
As a starting point for building an identity, that reminds you about your why. An example of this is the military, where a motto is the equivalent of a "why-phrase". The uniforms and the etiquette also represent the unconscious why.