I have little familiarity with Langs, so I'll address your second paragraph, first sentence. In researching some residency training issues for our department, I ran into the issue of how supervision is done. You point out accurately that there is a great deal missed if sessions are recalled by memory or brief notes. (There is data to support this.) And of course we of the Tomkins Institute recognize that there is a tremendous amount of non-verbal data, as Don Nathanson has pointed out. (Facial display, skin changes such as blushing, etc.) It would indeed be best to have supervisors in the therapy room, or at least to use audiotapes/videotape. Frightfully, few of us were trained that way...