Development of the current empirically oriented view of autonomic nervous system learning within a feedback framework is dicussed with attention paid to issues such as mediation and the choice of yoked control designs in experimental settings. Difficulties in establishing and assessing clinical changes, using a closed loop model, are discussed in terms of recent subvocalspeaking and heart rate research. A discussion of clinically oriented treatment guidelines focuses on three areas: response measurement, feedback information, and shaping. While there have been clear and positive clinical effects, the authors concluded that the factors which combine to produce an enhanced curative effect are not sufficiently delineated at this time.