Consciousness, Self, and the Prefrontal Cortex

cartesian-theater

There is a basic question that must be addressed when pondering the nature of consciousness, and that is: why have consciousness at all? The brain processes a great deal of information below the level of conscious awareness, from visual to auditory to tactile, and then the integration of all of these before they can be brought into conscious awareness. Yet conscious awareness itself seems much more limited in the amount of information that it can handle at a time—5 to 9 “chunks” of information, at a time, it would seem. So why rely on conscious awareness as heavily as we do? It certainly seems, at least from this angle, much less able than non-conscious processing—yet, given its apparent efficacy in raising humanity to the heights of culture and insight that we enjoy today, it surely has something essential to offer us.

The prefrontal cortex is the latest structure to appear in the evolution of the brain, and is the structure that shows the greatest development between humans and our closest biological relatives. Furthermore, it is known to mediate a great deal of the abilities considered distinctly human, such as planning, reflection, and empathy, all of which apparently require conscious awareness. Surprisingly, however, a vast abundance of the projections that the prefrontal cortex sends back to more primitive, sub-cortical structures are inhibitory—they function largely to suppress activity in these regions. In fact, this has led several researchers to rethink the concept of free will and, somewhat amusingly, refer to it rather as “free won’t,” in that we are mainly choosing what not to do, of all of the responses recommended by sub-cortical structures. And this is where we might find a reason for conscious awareness.

Consciousness relies on a crucial ingredient for dealing with the world in the way that the prefrontal cortex specializes in doing: it removes behavior from the moment-to-moment sensory perceptions incessantly presenting themselves to sub-cortical brain regions. Instead of constantly responding to each and every stimulus as it comes in, consciousness introduces a disconnect that allows reality apart from oneself to be treated as perceived, and thus distinct from the self and manipulable. Non-conscious responses don’t require perception in the same way that conscious processes do. In order to consciously ponder a course of action while planning, you need a virtual representation to work with, and in order to do that, you need some distance between yourself and the object being represented. Every day perceptions such as the visual field in front of you may function in a very similar manner: a stimulus presents itself, is processed by sub-cortical structures, and then a course of action is offered up to conscious awareness to be chosen or discarded by conscious reflection. There is a whiff of “opponent processing” going on in this narrative, something that comes up a lot in systems biology: two structures working in opposite directions in order to better center around a single desired outcome. Non-conscious, sub-cortical processing is largely reactive, leading to sometimes extreme, reflexive responses; conscious prefrontal processing, on the other hand, divorced from the constant demands of the environment, is more receptive to multiple courses of action, but can sometimes leave us unable to settle on an alternative. With the two of these working with opposing aims, however, behavior that is reactive enough to survive, but receptive enough to be a functioning member of society, can be attained.

This is far from a coherent theory or hypothesis, but the parallels between the roles of sub-cortical and non-conscious processes on the one hand, and prefrontal and conscious processes on the other, along with the connections between the two, are surely going to be important in mapping human consciousness.

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Predictability, Determinism and Free Will

In ordinary language, the concepts of predictability and determination are taken to mean roughly the same thing: if something is predictable, then it has definite causes that determine it to be the way it is; conversely, if something has definite causes that determine it to be the way it is, then it is, in principle, predictable. In philosophy, however, these are distinct concepts. Something that is deterministic need not be, in principle, predictable, and again, conversely, something that is predictable need not be deterministic. I will use two examples to illustrate this point, remarking on the second statement first, as I think it is the less significant of the two.

First, we will examine quantum physics. We would like quantum physics to be deterministic and may even have good reason to suggest that it must be, but at this point, we cannot say that with any certainty that it is, in fact, deterministic. Still, even supposing that it is not deterministic, we can use probability based models to predict, with sufficiently high precision, what the results, or outputs, of a quantum system will be.

Second, and I think more importantly, we can look to the universe at large. If we assume that the universe is entirely deterministic—which again we cannot say with any certainty but have good reason to think that it is—then it does not follow that everything in the universe need be predictable, in principle. We could say that a super-being with all the information about every single particle and its momentum could, theoretically, predict the state of the universe at any given time, but if we add materialism to this deterministic universe, this suggestion becomes meaningless. So let us think of it this way: if we want to model a system, we can represent each part of that system in a computer program. In order to do this, we will need to map each bit of information onto its own bit of computer coding, in a one to one fashion. Put simply, if we want to model a system with 10 components, we will need 10 bits of computer code, each mapping one of the ten components*. But we cannot do this with the universe at large. By definition, we need to map every single particle in the universe onto its own bit of computer coding—how can we do this? We have already exhausted every single particle in the universe by defining our system to be modeled—we simply have no particles left that could make up the computer coding for our program. Going back to our system of 10 components: if our universe only contains 10 particles, then we cannot model this system except by using the system itself as the model, but then we aren’t really modeling it, we are just watching the original system play out naturally. In this way, we can see that, even if our universe as a whole is deterministic, we still cannot, in principle, predict everything that is going to happen, because we, in principle, lack the means to do so, excluding the existence of non-physical super-beings.

To drive this home, I am going to borrow a quote from Richard Feynman:

It’s again this chess game business. If you were in just a corner where only a few pieces were involved, you could work out exactly what’s going to happen. And you can always do that when there’s only a few pieces, so you know you understand it. And yet, in the real game, it’s so many pieces you can’t figure out what’s going to happen. So there was a kind of hierarchy of different complexities. It’s hard to believe—it’s incredible, in fact most people don’t believe—that the behaviour of, say, me, one yack-yack, and you, nodding and all this stuff is the result of lots and lots of atoms all obeying these very simple rules.

To conclude, in a way, I want to remark on the relation between determinism, predictability, and our naive conception of free will. Part of the naive conception of free will is that we can, in principle, act in unpredictable ways. It simply is not the case that someone external to me could predict my own own behaviour with perfect precision. Often, the view of determinism, and its lay-equivocation with predictability, is seen as an attack on this conception of free will. But using the argument above, we see this need not be the case. We will never be able to predict the state of the universe at large, and if we cannot do say, we may always be misdefining one of the variables that we use to predict a local, closed system (i.e., for the purpose of this example, a human brain). Determinism does, in fact, have profound implications for free will if it turns out to be true, but they are much more subtle than they might seem at first glance.

*This is an oversimplification. We would also need computer coding for each of the laws describing the relations between the different components, but we will see that we need not even invoke these to illustrate the point.

Determinism, or Indeterminism: That is not the question.

In my Metaphysics class today, the following argument was put up for scrutiny:

1) If determinism is true, then no one acts freely, ever.

2) If indeterminism is true, then no one acts freely, ever.

3) Either indeterminism is true, or determinism is true.

4) Therefore, no one ever acts freely, ever.

5) If no one ever acts freely, ever, then no one is ever responsible for their actions.

Premise 1, in brief, relies on that assumption that if the world is deterministic, then everything that happened today was a necessary consequence of what happened millions of years ago. If everything that happened today was a necessary consequence of events in the distant past, then no person has any control over the present—it is all set in stone, as it were. Free will dictates a certain amount of control over present actions, so if this control is absent, then so is free will.

Premise 2, on the other hand, relies on a purely probabilistic definition of indeterminism. If events are indeterministic, which is to say that they are merely an odds game with event A having a 40% probability, and event B having a 60% probability, then we still lack any sort of “control” over the situation. Which event occurs is largely arbitrary, relying only on some unknown odds, written in the sky or otherwise.

This is not to say that these are the only ways in which premises 1 and 2 can be formulated, but this is how they were presented in this case.

Most of the objections raised, both in my class and in the literature, from what I’ve seen,  have attempted to disprove either premise 1 or 2. That is, there can be free will under determinism, or there can be free will under indeterminism. Most of these amount to some re-formulation of free will. I will not be taking either of these positions. Instead, I will attack premise 3: That the world is either deterministic or indeterministic.

The core of my argument rests on the claim that premise 3 presents a false dilemma. It is either determinism, or it is indeterminism, but not both. I assert that it is, indeed, both, or at the very least, we are not in a position to rule this possibility out. Current physics, which is where most of these theories claim to have their support, does not itself claim to have sorted this issue out. We know that under certain circumstances, such as when the scale is microscopic, that the world behaves in an apparently indeterministic way. Under other circumstances, such as when the scale is macroscopic, the world behaves in an apparently deterministic way. Many propose that we can link these two, and show that it is really one, and not the other, in virtue of a fundamental property of nature: namely parsimony—or, that the universe is, at its most fundamental, simple (simple in the sense that it all can be reduced to more or less the same thing). But, what they miss, is that it does not have to be this way. There is, in fact, no law that says that the universe must be simple. It may very well turn out that the universe is complicated, perhaps even too complicated for us to understand it, in the proper sense of the word.

(The following is mere speculation, I have absolutely no empirical basis for the ideas that follow; however,  I still, personally, find a great deal of plausibility in them, but you have been warned, nonetheless!)

Building off of this, and the fact that most of the arguments that place free will either in a purely deterministic or a purely indeterministic light typically have to resort to a reformulation of free will itself, I now assert that free will is only a coherent construct in a world that is both deterministic and indeterministic. What I propose is the following, which relates this more specifically to the theme of this blog: free will can only exist in conscious creatures. This may seem unnecessary to state in so many words, but the following should provide reasons for it. Complex brains are, in a general sense, specialized organs for planning and deliberation. Given that the microscopic events of this world are largely indeterministic, and that the macroscopic events are largely deterministic, we can postulate the following: brains serve to make sense of a vast multitude of indeterminacy. Through the process of evolution, and, to steal a phrase from a neuroscientist I once knew, thanks to the goddess of molecular evolution, they came to be in a position to turn underlying indeterminacy into coherent, conscious actions. This is not an appeal to a “collapse-of-the-wave-function” view of consciousness, to be clear. Rather, it is an attempt to reconcile the disparate aspects of reality into one coherent framework.

We can use this argument to strike down some of the objections raised to both purely deterministic and purely indeterministic accounts of free will. One variety of the former asserts that if you could not have acted otherwise, then you could not have acted freely, as stated above. If there is some underlying indeterminacy, however, this is clearly not the case. There are, in fact, a multitude of different ways in which you could have acted. Aha! But this just reduces to a variety of the argument from indeterminacy—that actions are merely arbitrary instantiations of probabilities, right? But that is where the deterministic aspect of reality kicks in. Once the most basic underlying facts about the world are set, in a probabilistic fashion, then determinism takes over. For this, I draw on an idea put forth by John Searle: downward causality, but in no way do I claim to restate his argument. The higher-order functions of the brain, namely consciousness, do indeed have “causes” that exist as smaller, microscopic bits, but these higher-order functions also have the ability to rain down causation on these smaller bits, much in the way that higher-order theories of economics can influence the activities of lower level commodities. Neither of these can be “smoothly reduced,” as Searle puts it, to the other, but that does not imply that one or the other does not exist, or play a meaningful role. In fact, Searle says that typically, reduction of one thing to another serves the purpose of showing that one of those things does not exist, not the other way around, as is often claimed.

This may seem counter-intuitive, and in some ways, it does have to re-formulate the popular idea of free will. In particular, it draws a distinction between free will at its most basic on the one hand, and conscious will on the other. Conscious will, or the idea that you are consciously in control of all of your actions and thoughts, is inevitably false. A handful of psychological experiments demonstrating non-conscious biases and predispositions shows this very simply. But this is not what we are talking about when we say free will, or so I claim. Free will is much more general than the limited definition of conscious will. At its most basic, it requires that you be capable of acting in certain ways that rely on intentional stances. Even if you are not consciously aware of your decisions to act in certain ways, it is still you that is making them. You are your brain, and everything that comes along with it. Simply because something is non-conscious does not make it any less a part of you. It may clash with the popular account of who you are, but at the end of the day, you are made up of more non-conscious pieces than conscious pieces, so restricting our definition of free will to the conscious pieces seems to make little sense. Now, this is not to say that our conscious feeling of free will is irrelevant, but it is a different matter to bring up—specifically, it is more of an epistemic question than a metaphysical question.

On the time-scales of free will

In the past few decades, many empirically-bent workers in cognitive science, psychology, and philosophy have taken it upon themselves to correct our illusion that we have free, conscious will. The problem that many of these theorists overlook, however, is that the idea of free will can be separated into two relatively independent processes, differentiated by their respective time scales: short and long.

Short term physical activities are largely concerned with constructing the appropriate movements to match the current situation, like picking up and writing with your pencil, or walking down a street—both of which require incredibly complex movements from a basic systems level. The nature of our nervous system, however, allows such movements to be written into the system itself, such that the resulting structure of the system allows these movements to take place with little information processing needing to be done.

Correspondingly, in the realm of the brain, both empirical and theoretical viewpoints do, indeed, point to a remarkably diminished activity of free will—one need only think of split-second decisions as an example. A great many of these split-second decisions turn out differently than we would have preferred, given a chance to deliberate. This side of the issue makes sense from a biological/organismal standpoint: If we have incredibly complex brains that are capable of a great deal of things without conscious attention, why not take advantage of that when it comes to basic mental events? In this way, short term mental events and short term physical events are not so different. Such a method of functioning allows more resources to be devoted to other higher-order matters of cognition, such as planning and deliberation.

Planning ahead and considering possible alternatives is where the long term variety of conscious will starts to play a significant role. Planning and deliberation are not merely a system of inputs onto your nervous system with a more or less pre-set outcome, as is the case in many short-term scenarios. It involves assignment of value to certain outcomes, and a subsequent weighing of those values against one another. Note that I am not trying to say that long-term planning is not ultimately a result of physical actions in the brain, but rather that it is not so simple as its short-term counterpart. I am also not saying that these two time-scales are fully separate—if I were, then the long-term system could not influence the short-term system and people could not be help responsible for their actions. My view is instead that long-term systems work to influence and entrain the short-term systems towards a desired pattern of outputs. The details of this system need to be worked out, but the cursory description lines up more closely with experience than the one outlined at the top of the article.

The problem with those who use currently available empirical data to undermine free will, then, can be summed up quite simply. All of their data is built around short-term decisions. But even advocates of free, conscious will see reason to doubt short-term decisions as being fully controlled by consciousness. So, in effect, the present researchers are merely proving something true that most experts already thought true. The only objection to them, is this: short-term data do not reveal much of anything about long-term phenomenon. For a clearer example, the composition of a small pile of sand on a beach does not reveal much about the grander process of tidal erosion.

On the (Supposed) “Illusion of Conscious Will”

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The image above (from Blackmore 2005) is designed to show that we are not truly in control of our actions, or at least not in the way that we intuitively believe we are. There are, however, a number of flaws, or at least oversights or shortcomings, associated with this position that I’d like to illuminate:

1) The schematic presented is based on only a handful of empirical results. At most, this can be used to explain those results. Of note is that the experiments that generated these data were designed with the express purpose of deceiving the subjects. This in mind, the model fits those phenomena almost perfectly. As for its generality to ordinary phenomena, the link is less than clear, at best. Either way, further research is needed.

2) If we accept that the model is intended to be a general principle, then we can still point out that it overlooks the possibility of downward causality, or at least an interaction between thought and action. This could be shown by an additional causal path between the processes that, respectively, generate conscious thought and behaviour, downstream of the initial breakpoint. If nothing else, this would allow for mutual reinforcement or modification between conscious thought and associated behavioural outcomes. This position lies somewhere between fully conscious control and fully illusory conscious control, and seems most plausible.

3) Further, defining conscious control as fully separate from non-conscious processes is to define it so that it is necessarily false, excepting an embrace of true substance dualism. It is generally accepted that consciousness arises from brains, again excepting substance dualism. Combined with the evolutionary fact that consciousness evolved closer to the present than did non-conscious processes, it stands to reason that all conscious processes depend in some way on non-conscious processes. This does not extinguish the role of conscious thought, it merely splits the role of control between non-conscious and conscious mechanisms, but says nothing as to the balance between the two. This might be seen as an attack on free will, but it actually fits everyday intuition better than either of the extreme views. For example, most people recognize the power of reflexes and internal biases–these represent part of the non-conscious aspect of control. Planning and deliberation, on the other hand, make up part of the conscious side, though parts of these could be arguably identified as non-conscious (and vice-versa for the non-conscious processes listed above, as conscious control can influence internal biases).

This last point is largely an objection to a specific piece of empirical data and its interpretation in some circles that is in many ways similar to Wegner’s above. The view goes like this: The physiological correlates of an intention precede conscious awareness of an intention. Therefore the intention is not consciously formed, it is entirely the result of non-conscious processing. As above, this approach seems misguided. To assume that a conscious thought could simply spring into existence before any underlying neurobiological activity can be recorded is nothing more than substance dualism–and is not the view that needs refuting. If conscious states arise from the brain, then it holds that some activity in the brain must occur before a thought can be known. Does this fully discount conscious thought as a causative agent? My response, as above, is a definite no, it simply shows that not all aspects of the causation for behaviour can be accounted for by conscious intentions. This is not the same as saying that none of it can be.