Thus, we are faced with the puzzle: how can we know when we are not communicating as effectively as we think we are?

How can we become aware that we are unaware?

EXPERIMENT WITH A NEW FRAME.
Most of us believe that we communicate well. While this may be true, this belief itself increases the odds that we will not recognize those instances when we do not. Don't think of communication as a skill with which you have achieved competency or not. Instead, think of each interaction as a challenge in which your goal is both to understand the others' perspective and to help them understand yours. Recognize that there will be times when you fall short of this goal, and being aware of when it is happening is the first step towards improvement.

SEEK EVIDENCE.
Be on the lookout for those times when you are not communicating successfully. Do you find yourself having the same conversation again and again? Do you find that issues you thought were resolved continue to resurface? Is an interaction triggering strong emotions that are making it hard for either party to express themselves or listen? These all may be signs that you are not communicating as effectively as you want.

CHECK YOUR BLIND SPOTS.
It is easy to see what others are doing and the impact they are having on us. However, we have natural blind spots regarding others' intentions and the impact we are having on them. When you are frustrated or dissatisfied, get in the habit of regularly asking yourself, "How might I be inadvertently contributing to these results?"