In his book What Intelligence Tests Miss: The Psychology of Rational Thought, Keith Stanovich explains how cognitive psychologists define rationality. They distinguish two basic forms of rationality: 1) INSTRUMENTAL RATIONALITY, behaving in such a way that you achieve what you want, and 2) EPISTEMIC RATIONALITY, taking care that your beliefs correspond with the actual structure of the world.
At the risk of simplyfying too much, instrumental rationality seems to be about doing what works and epistemic rationality is concerned with truth and refers to seeing reality for what it is. It seems to be a pitfall to overlook any of these two rationalities. Only focusing on what is true but forgetting to do what works may lead to your neglecting to do things that help you to survive and remain connected to other people (A). Only focusing on doing what works but neglecting the what is true question may lead to you moving efficiently through a web of falsity distancing you more and more from reality (B). Thinking about this I thought of visualizing this as follows: