The development of critical thinking skills and the "maturing" of a professional occur in every discipline. The experienced practitioners find themselves looking at the novice level with a new understanding when applying human factors and purposeful self-reflective thought. Using human factors and the critical thinking process to map this experiential change in health care allows for progress toward a culture of safety. Application of human factor science to critical thinking development and measurement of critical thought in the error process yields new insight to the delivery of safe health care.