If it does not make the patient think twice [There is nobody to look through the window.] It does not change anything. If it does, than it will hinder the therapy. See above.
Fair enough. However, unless I’m mistaken (and please feel free to correct me), most therapy of this type is strictly verbal (i.e. the patient sits in a chair and simply talks or follows simple instructions from the therapist). As such, as long as you don’t have people actively listening at the door, it wouldn’t appear like anything other than two people having a conversation.
The Wolf