people and organizations. This theory defines learning as detection and correction of error. It included the distinction between single-loop learning and double-loop learning in 1978. Single-loop learning is when a practitioner or organisation, even after an error has occurred and a correction is made, continues to rely on current strategies, techniques or policies when a situation again comes to light. Double-loop learning involves the modification of objectives, strategies or policies so that when a similar situation arises a new framing system is employed. Schön claimed to derive the notions of "reflection-on-action, reflection-in-action, responding to problematic situations, problem framing, problem solving, and the priority of practical knowledge over abstract theory" from the writings of John Dewey, although education professor Harvey Shapiro has argued that Dewey's writings offer "more expansive, more integrated notions of professional growth" than do Schön's. Schön advocated two types of reflective practice. Firstly, reflection-on-action, which involves reflecting on an experience that you have already had, or an action that you have already taken, and considering what could have been done differently, as well as looking at the positives from that interaction. The other type of reflection Schön notes is reflection-in-action, or reflecting on your actions as you are doing them, and considering issues like best practice throughout the process. For Schön, professional growth really begins when a person starts to view things with a critical lens, by doubting his or her actions. Doubt brings about a way of thinking that questions and frames situations as "problems". Through careful planning and systematic elimination of other possible problems, doubt is settled, and people are able to affirm their knowledge of the situation. Then people are able to think about possible situations and their outcomes, and deliberate about whether they carried out the right actions. Gibbs 1988 Learning researcher Graham Gibbs discussed the use of structured debriefing to facilitate the reflection involved in Kolb's experiential learning cycle. Gibbs presents the stages of a full structured debriefing as follows: (Initial experience) Description "What happened? Don't make judgements yet or try to draw conclusions; simply describe." Feelings "What were your reactions and feelings? Again don't move on to analysing these yet." Evaluation "What was good or bad about the experience? Make value judgements." Analysis "What sense can you make of the situation? Bring in ideas from outside the experience to help you." "What was really going on?" "Were different people's experiences similar or