I read an article from the economist subtitled "The evolutionary origin of depression" which puts forward the following hypothesis:
As pain stops you doing damaging physical things, so low mood stops you doing damaging mental ones—in particular, pursuing unreachable goals. Pursuing such goals is a waste of energy and resources. Therefore, he argues, there is likely to be an evolved mechanism that identifies certain goals as unattainable and inhibits their pursuit—and he believes that low mood is at least part of that mechanism. ...
This ties in with Kaj and PJ Eby's idea that our brain has a collection of primitive, evolved mechanisms that control us via our mood. Eby's theory is that many of us have circuits that try to prevent us from doing the things we want to do.
Eliezer has already told us about Adaptation-Executers, not Fitness-Maximizers; evolution mostly created animals which excecuted certain adaptions without really understanding how or why they worked - such as mating at a certain time or eating certain foods over others.
But, in humans, evolution didn't create the perfect the perfect consequentialist straight off. It seems that evolution combined an explicit goal-driven propositional system with a dumb pattern recognition algorithm for identifying the pattern of "pursuing an unreachable goal". It then played with a parameter for balance of power between the goal-driven propositional system and the dumb pattern recognition algorithms until it found a level which was optimal in the human EEA. So blind idiot god bequeathed us a legacy of depression and akrasia - it gave us an enemy within.
Nowadays, it turns out that that parameter is best turned by giving all the power to the goal-driven propositional system because the modern environment is far more complex than the EEA and requires long-term plans like founding a high-technology startup in order to achieve extreme success. These long-term plans do not immediately return a reward signal, so they trip the "unreachable goal" sensor inside most people's heads, causing them to completely lose motivation.
However, some people seem to be naturally very determined; perhaps their parameter is set slightly more towards the goal-driven propositional system than average. These people rise up from council flats to billionaire-dom and celebrity status. People like Alan Sugar. Of course this is mere hypothesis; I cannot find good data to back up the claim that certain people succeed for this reason, but I think we all have a lot of personal evidence that suggests that if we could just work harder, we could do much better. It is now well accepted that getting into a positive mood counteracts ego depletion, see, for example, this paper1 . One might ask why on earth evolution designed the power-balance parameter to vary with your mood; but suppose that the mechanism is that the "unreachable goal" sensor works as follows:
{pursuing goal} + {sad} = {current goal is unachievable} ==> decrease motivation
{pursuing goal} + {happy} = {current goal is being achieved} ==> increase motivation
And the "mood" setting takes a number of inputs to determine whether to go into the "happy" state or the "sad" state, such as whether you have recently laughed, whether you received praise or a gift recently, and whether your conscious, deliberative mind has registered the "subgoal achieved" signal.
In our EEA, all of the above probably correlated well with being in pursuit of a goal that you are succeeding at: since the EEA seems to be mostly about getting food and status in the tribe, receiving a gift, laughing or getting more food probably all correlated with with doing something that was good - such as making allies who would praise you and laugh and socialize with you. Conversely, being hungry and lonely and frustrated indicate that you are trying something that isn't working, and that the best course of action for your genes is to hit you with a big dose of depression so that you stop doing whatever you were doing.
Following PJ Eby's idea of the brain as a lot of PID feedback controller circuits, we can see what might happen in the case of someone who "makes it": they try something which works, and people praise them and give them gifts (e.g. money, business competition prizes, corporate hospitality gifts, attention, status), which increases their motivation because it sets their "goal attainability" sensor to "attainable". This creates a positive feedback loop. Conversely, if someone does badly and then gets criticism for that bad performance, their "unreachable goal" sensor will trip out and remove their will to continue, creating a downward spiral of ever diminishing motivation. This downward spiral failure mode wouldn't have happened in the EEA, because the long-term planning aspect of our cognition was probably useful much more occasionally in the EEA than it is today, hence it was no bad thing for your brain to be quite eager to switch it off.
So what are we to do? Powerful anti-depressants would seem to be your friend here, as they might "fool" your unreachable goal sensor into not tripping out. In a comments thread on Sentient Developments, David Pearce and another commenter claimed that there are some highly motivating antidepressants which could help. Laughing and socializing in a positive, fun way also seem like good ideas, or even just watching a funny video on youtube. But we should definitely think about developing much more effective ways to defeat that enemy within; I have my eye on hypnosis, meditation and antidepressants as big potential contributors, as well as spending time with a mutually praising community.
1. Restoring the self: Positive affect helps improve self-regulation following ego depletion, Ticea et al, Journal of Experimental Social Psychology
I'm not disagreeing with what you said, I'm only disagreeing with what you said I said. Clearer now? ;-)
It's true that PCT (at least as described in the 1973 book) doesn't take adequate account of predictive modeling. The model that I was working with (even before I found out about the "memory-prediction" framework) was that people's feelings are readouts of predictions the brain makes, based on simple pattern recognition of relevant memories... aka, the "somatic marker hypothesis".
What I've realized since finding out about PCT, is that these predictions can be viewed as memory-based linkages between controllers - they predict, "if this perception goes to this level, then that perception will go to that level", e.g. "IF I have to work hard, THEN I'm not smart enough".
I already had this sort of IF-THEN rule formulation in my model (described in the first draft of TTD), but what I was missing then is that in order for a predictive rule like this to be meaningful, the target of the "then" has to be some quantity under control -- like "self-esteem" or "smartness" in the previous example.
In the past, I considered these sort of simple predictive rules to be the primary drivers of human behavior (including rationalizations and other forms of verbal thinking), and they were the primary targets of my mindhacking work, because changing them changed people's automatic responses and behavior, and quite often changed them permanently. (Presumably, in cases where we found a critical point or points in the controller network.)
This seemed like a sufficient model to me, pre-PCT, because it was easy to find these System 1 rules just underneath System 2's thinking, whenever a belief or behavior pattern wasn't working for someone.
Post-PCT, however, I realized that these rules are purely transitional-- merely a subset of the edges of the control hierarchy graph. Where before I assumed that they were passive data, subject to arbitrary manipulation (i.e. mind-hacking), it's become clear now that the system as a whole can add or drop these rules on the basis of their effects on the controllers.
Anyway, I'm probably getting into too much detail, now, but the point is that I agree with you: merely having controllers is not enough to model human behavior; you also need the memory-predictive links and somatic markers (that were already in my model), and you need PCT's idea of the "reorganization system" -- something that might be compared to an AI's ability to rewrite its source code, only much much dumber. More like a simple genetic-programming optimizer, I would guess.