Beck's understanding of free association and the fundamental rule can be read and heard in various places, but the one I want to consider is available here. To quote:
I was seeing a patient named Lucy. She was on the couch, and we were doing classical analysis. She was presumably following the "fundamental rule" that the patient must report everything that comes into her mind. During this session she was regaling me with descriptions of her various sexual adventures. At the end of the session, I did what I usually do. I asked her "Now, how have you been feeling during this session?" She said "I've been feeling terribly anxious doctor".
...I said "It's very clear why you've been feeling anxious. You have these sexual impulses which are threatening to burst forth. Since your sexual impulses are unacceptable they cue off anxiety." I said "Does that sound right?" She said "Oh yes, you're right on target." I said "Do you feel better now that you know this?" She responded "No, I feel worse". I replied "Thank you for being frank. Can you tell me a little more about this?" She responded "Well actually, I thought that maybe I was boring you, and now that you said that, I think I really was boring you." I asked "What made you think that you were boring me?" She replied "I was thinking that all during the session." I said "You had a thought "I am boring Dr Beck", and you didn't say it?" She replied "No, I never thought to say that." I said "You had that thought just this one time, right?" She responded "Oh no, I always have that thought". I said "Oh that's really strange. How come you never reported this before?" She responded "It just never occurred to me that this would be the sort of thing you would be interested in." I asked "Did you have any feeling when you had this thought?" She replied "Well this is what has made me really anxious". I asked "Do you ever get this thought when you're not in the session?" She replied "Oh, I get it with everybody. I'm always very anxious because I think that I'm boring people."Beck starts by telling us that Lucy was 'presumably following the 'fundamental rule''. We then learn however that she was doing no such thing. As Jonathan Lear has stressed, to follow the fundamental rule is impossible. It is in the nature of being analysed that one very often does not say what is on one's mind. One may take oneself to be doing that at the time. But then, when the session's over, one thinks: 'Oh, how come I never voiced that worry about what my therapist would think of my saying this or that? The worry was there all along!' (Beck himself was in analysis for a few years. How come he never realised this himself?!) This tells us something really interesting and important about the nature of the unconscious: how the image of repression as obscuring and burying what is on one's mind is not quite right. What is repressed is in fact known perfectly well, yet peculiarly 'un-thought' as Christopher Bollas calls it. (Sometimes I think that what is repressed becomes like a default tacit framing assumption: something that is rather imagined to go without saying. Both the patient and the analyst 'know' that the patient is basically boring - this much is already down - so let's not state the obvious and instead keep what would be a painful thought unconscious - in the curiously too-well-known-and-yet-thereby-not-known-at-all miasmic sea in which the analytic relationship floats.)
Anyway, Beck's therapy with his patient gets better when she stops trying to meet his needs and starts addressing her actual worries. It gets better, one could say, when she starts 'complying' better with the fundamental rule. Then the two of them can work through her transference worries. Beck calls these worries her 'negative automatic thoughts', and implies that they are only incidentally ignored by her, and that she just needs training to look at them. I would suggest, however, that the connection between her not voicing the worry that she was boring him, her belief that she ought to be saying things interesting to him even though it's her therapy, and her fear of boring him are clearly connected! Their connectedness forms the flesh of the motivational dynamics of the internal world, a world on which Beck effectively turns his back as he turns his back on the transference and develops instead a coaching relationship.
Here, however, let's just note the vast difference between saying whatever it occurs to you to say, and saying whatever is actually on your mind. Beck seemed to have no sense, in his analytic work, of this difference. He seemed to have no idea that if someone really could comply with the fundamental rule then they wouldn't need to be coming to psychoanalysis!
Why is it hard to grasp the meaning of 'free association' - 'frier Einfall' Partly the term itself I'd suggest (I'm following Guy Thompson on the fundamental rule). It is in one sense neither 'free' - because as Thompson notes psychoanalysis is governed by a constraining ethic of honesty (you really gotta try to share stuff you donna wanna share). Nor is it about associating a la associationist psychology - since one can just as well associate away from one's real emotional preoccupations as towards them (as Jon Frederickson describes in his books on therapy). Rather it's all about actually sharing what is actually on your mind - which is so much more readily known than thought, and which we are in any case so often reluctant - even instinctually, unreflectively reluctant - to do.