From source that is external to performer. Naturally occurring part of performance situation. Movement characteristics that lead to outcome. Augmented feedback is essential except for when The performer cannot see target.
Special injury leads to deafferantation.
Person is incapable of using feedback. Augmented feedback can hinder skill learning if it is wrong. Error related information works better to facilitate skill acquisition. Information about correct performance motivates a person. How large an error required before augmented feedback.