Friday, April 26, 2013

The invisible blog

So, the term 'common currency' is mostly used to talk about currency unions. This is, of course, where more than one political entity - usually a state - use the same currency in the sense of money.

The term used much less frequently in the sense relevant to this blog, which is with reference to decision, pattern in choices, and the processes by which choices are produced. As a result this blog is, so far, barely visible. Except for social traffic from people who pay attention to my personal activity on Facebook and Twitter, there's almost no traffic at all. Part of the problem is the dominance of what for me are irrelevant uses of 'common currency'. Even searching for "common currency brain science blog" doesn't (yet) return results where this site is anywhere near the top.

I'm going to try to take a few steps to improve matters. One of those is signing the blog up on Research Blogging, so that appropriate posts can be digested and appear in their feeds. I'll also see what I can do to generate some more inbound links.

Wednesday, April 24, 2013

Image collection: Brain dollars, dollar brains

The field of neuroeconomics has been attracting a certain amount of popular press, and also generating a growing number of book and special issue publications. Both of these drive appetite for illustrations. And people sometimes seem very keen to distinguish their illustrations from the general sorts of “pictures of brains” that go with other publications about neuroscience. So what are they to do?

It turns out that a fairly common approach is to throw together something that superimposes images of brains and images of cash, or that show brains and cash in some kind of interaction.

It takes only a little thought to see that some of the images are actually pretty silly. My reading (about common currencies) keeps taking me to places where I see these things, and so I’m going to start collecting them and posting them here. If you run into an image that you think belongs in the gallery, please either comment below or email me. (I’d also really welcome pointers to good images relating to the idea of value representation in the brain, such as the Society for Neuroeconomics logo below. This gallery is not just a Hall of Shame.)

Category 1: Brains or skulls with money on or in them

It is common to think that different motives can compete, and that that individual ones can differ in how motivating they are. At different times people have been tempted to use different metaphors to express this. When Newton was a relatively fresh and salient inspiration, it was more common to use the term ‘force’ to describe what motives had, and what some of them had more of. I’m not sure when it became popular to describe the process of deciding between competing motives as a kind of ‘weighing’, but I’d guess it was when balance scales were part of everyday experience. These days the fashionable metaphors are economic, and specifically related to cash. This is part, I think, of why ‘common currency’ talk is increasingly popular.

Exhibit 1.1: A skull with a hand holding a fan of cash in it.

It's not clear what to make of this. What controls a hand sticking out of the spinal column? Who or what might see or interact with the money?

Exhibit 1.2: Synapses forming a suggested dollar sign


This is the rather cool logo of the Society for Neuroeconomics. I like that the dollar sign is suggested and entangled rather than superimposed.

Exhibit 1.3: Clunky dollar signs on a murky brain


This one is a 'bottom of the barrel' FAIL on the APA website. It's pictures like this that made me think of posting this gallery.

Exhibit 1.4: Single clunky dollar sign on a murky brain

This is remarkably similar to exhibit (1.3) above. The page it's from is in Russian, and I have no idea what it's about, but it turns up on searches for 'neuroeconomics'.

Exhibit 1.5: Skull looking at a dollar bill

So this is basically exhibit 1.1 above, but with the hand and the bill outside the head.


Category 2: Money with brains on or in it

Showing cash in or on the brain can suggest the idea of brains processing representation states related to value or utility. So some category 1 pictures can sort of make sense. The converse idea, that there might in any sense be a coherent metaphor where there are little brains in the cash, is rather farcical. This does not prevent some designers from adopting it, and some editors from approving it. Here are a few examples.

Exhibit 2.1: Dollar bills with heads and brains on them


This (the logo for a project on the "Neuroeconomics of controversial food technologies") really speaks for itself. But what is it saying?

Exhibit 2.2: One Dollar bills with one brain on it


The brain in this money is glowing. Maybe it was bitten by a radioactive banker, or something.

Category 3: Brains and money in some kind of interaction

Exhibit 3.1: The weighing metaphor, with brains and cash


This is pretty odd if you think about it. Unless your concern is the price of brains. Which I suppose it might be, if you were an economically active zombie. But if the brain is in the scale, then it isn't doing the weighing, or reading off the values. So what or who is? Maybe there are little brains inside brains, and the little brains do all the processing. (The same picture also appears on the cover of the important collection "Neuroeconomics: Decision Making and the Brain" edited by Glimcher, Fehr, Camerer and Poldrack. [Publisher link.])

Category 4: Miscellaneous

Exhibit 4.1: Head chart

So here's a quite fetching little image. There's no cash in the skull, or bits of brain somehow stuck onto the cash. But there's a data line of some kind that looks price-like, and with an arrowhead suggesting a projection beyond where the data runs out. It makes much more sense to think that brains represent costs and/or returns, and projects trends, than to think that they've got little banknotes in them.


Monday, April 22, 2013

The (very) basic big idea

Buridan' Ass
Old illustration of Buridan's Ass (famously indifferent between two food options).

If you’re struggling for a rough sense of what the hell I’m talking about on this site, then this post is supposed to help. It’s deliberately non-technical and informal. My aim is to give a fairly general and intuitive sense of the idea of a common currency, and avoid the technical details that go with how that concept is regimented in various sciences.

Consider any two things that you want. Here are some possibilities:
  1. You want each of them to about the same degree.
  2. You want one of them more than you want the other.
  3. There’s no fact of the matter about how(or whether) the degree to which you want them differs.
Suppose, further, that in this case possibility number (3) does not apply. (This isn’t a trivial thing to suppose – and I’ll discuss it in future postings.)

Now suppose that either option (1) or (2) applies not just to the particular two things that you initially imagined, but to every possible pair of things taken from the whole set (possibly infinite) of things that you want.

Then your wants would form a kind of list (possibly infinite), where every item on the list had a definite ranking (perhaps with some on the same rankings).

Those rankings would form a kind of common currency, like positions in a race (first, second, third, etc.). It would be common because everything you want would be somewhere on it.

It’s important that the ranking should include things that you don’t want too, because (a) you should want them less than things you positively want (possibility 1 or 2 above should apply to each of them), and (b) because they’re not all equally horrid. This means that we can (if we want) imagine the ranking to represent the net desirability of the things on it. (So a cupcake that costs ten dollars, or ten minutes of effort, could come lower than the very same cupcake for one dollar, or one minute of effort.) But we could also represent the costs as negative wants on their own, and suppose that net desirability is calculated (by subtracting costs from outcomes). Those are different ways of representing the same information.

We might imagine that the strengths of our wants are a little more quantitative. So, I might say not merely that I want a cup of coffee more than I want a glass of water, but that I want a cup of coffee twice as much as a glass of water. If every pair of our wants stood in this kind of relationship, then they would all have definite relative degrees of desirability. This would give a similarly common scale, but one that includes information about the relative sizes of the gaps between positions.

There are at least two ways of thinking about this ‘common currency’ scale, or dimension:
  • In one case, it is a set of facts about the pattern in the actual choices you make. (One way of thinking of this is to suppose that an economist or behavioural researcher had observed a lot your activity and inferred the relative value of different outcomes from your choices. Such researchers might at least be agnostic about is be going on inside you. Many economists and behaviourists are officially agnostic about the inside, even though they’re committed to common currencies.) I’ve explained elsewhere on this blog that I find it useful to call this kind of “pattern in choices” currency ultimate.
  • In the other case, it is a set of facts about the processes by which your choices are generated. One way to think about this is to think that your wants, or desires, or preferences, are real psychological states of yours. Another (which need not be the same thing) is to suppose that the strengths of your wants are represented in neural activity in your brain. I’ve explained elsewhere on this blog that I find it useful to call this kind of “process producing choices” currency proximal.

It turns out that scientists of various kinds (including behavioural ecologists, economists, behavioural psychologists, and neuroeconomists) argue that there is a common currency for at least some kinds of agent. But they sometimes argue for ultimate currencies, and sometimes proximal ones, and they use different kinds of evidence and theory to defend their positions.

It’s also not difficult to find examples of people denying that there is a common currency. Some deny it for humans, partly because they find it offensive to suppose that our most noble wants might appear on the same scale as our most base ones. Some deny it for some classes of animal or robot, usually saying that internal representations (including of strength of preference) aren’t necessary for orderly behaviour.

I’m interested in the tangle of claim and counter-claim that this combination of arguments in favour and against produces, when looked at comparatively. To get an idea of what I’m working on see My OwnEfforts and the links there.

See also:

Important Sources: Rodney Brooks – Denies representations for at least some robots, so denies proximal currency.
Important Sources: Kim Sterelny – Seems to hold a position sharing some key features with Brooks.
Important Sources: George Ainslie – Staunch defender of common currency thesis.

Thursday, April 18, 2013

Intragenomic Conflict and Common Currencies

‘Intragenomic Conflict and Common Currencies’ is the working title of one of the papers that is part of this common currency project. It grew out of my reading of an essay by David Haig called ‘Intrapersonal Conflict’ which is the first piece in an anthology simply called Conflict (Cambridge, 2006, edited by M Jones and AC Fabian).

Picture showing differences between embryos of mice where genetic imprinting had been manipulated. (See the powerpoint slides below.) Image from Haig (citation below) in turn from Keverne et al.

I presented a very preliminary version of the argument at the 2013 conference of the PSSA, at the Salt Rock Hotel, in KwaZulu-Natal, South Africa. Because I’d also been organizing the conference, the talk wasn’t as worked out as it might have been.

More recently (April 17, 2013) I presented an updated version to the senior seminar at UKZN, and I’ll be taking the same talk to the University of Johannesburg around the end of April.

The written draft of the paper is still something of a construction site, but my presentation slides may be of some interest, and so I’m posting them here.

I’ll post updated slides from future presentations (right here on this page), and eventually the working draft of the paper when it’s ready for comment and feedback.


Haig D (2006) Intrapersonal conflict. In: Jones M, Fabian AC (eds) Conflict. Cambridge University Press, Cambridge, pp 8–22.

Tuesday, April 16, 2013

Not dead, just researching

Things have been quiet here for a while, I know.

This must be a great inconvenience to my staggeringly tiny readership.

I've been working like crazy getting a working version of "Intragenomic Conflict and Common Currencies" into shape. (See My own efforts on this site. This is a paper occasioned by David Haig's "Intrapersonal Conflict". I'm also presenting a version of this at the Australasian Association of Philosophy conference in July this year.)

I'm presenting the paper tomorrow afternoon. Shortly after that, I'll probably put my slides up, so that they can bask in the blazing obscurity of this here blog. Some time after that, I may even post a working version of the paper (the prose version is still largely a construction site.) Once the presentation is done, I'll have time to finish a few draft pieces for this blog that are taking shape, and add to the preliminary discussion of important distinctions in this area.

Tuesday, April 9, 2013

Important Sources: Rodney Brooks


Picture of the robot 'Herbert' from: 
People who think that there is a proximal common currency[1] for some type of agent think that the values of possible actions open to that agent are represented in its cognitive states.

One way to deny this is to deny that agents need cognitive states of any significant kind. This, more or less, is what Rodney Brooks went around doing in the late 1980s and early 1990s.

Here I take a quick look at his classic 1991 paper “Intelligence Without Representation”. I note some of the ways that it constitutes a challenge to some views about common currencies. In his paper Brooks talks about the design of a large class of mobile robots that he collectively calls ‘creatures’. All quotations are from Brooks (1991).

What should creatures be able to do?

In Section (4) of his article Brooks lists some ‘requirements’ for his ‘creatures’. One of these requirements is a reason for thinking that what he has to say is relevant to the common currency question:

“A Creature should be able to maintain multiple goals and, depending on the circumstances it finds itself in, change which particular goals it is actively pursuing; thus it can both adapt to surroundings and capitalize on fortuitous circumstances.”

This certainly gives the impression that creatures are supposed to cope (somehow) with multiple goals and varying conditions. That’s the sort of problem that often leads people to hypothesise a unified value representation like a common currency.

Brooks, of course, is famously anti-representation. So shortly after he has stated his goals, he gets down to describing the conventional approach he rejects, which involves ‘decomposition by function’. Here he says:

“Perhaps the strongest, traditional notion of intelligent systems (at least implicitly among AI workers) has been of a central system, with perceptual modules as inputs and action modules as outputs.”

While Brooks doesn’t say so himself, this ‘central system’ is clearly the kind of place where values (in a common currency) could be attached to possible actions. The main reason Brooks doesn’t say so, I suggest, is that the paradigmatic representationalist is also a cognitivist, who devotes much more attention to epistemic states (perception, memory, reasoning) than to motivational ones.

Next, in Section (4.2) Brooks describes the alternative approach that he favours, which is ‘decomposition by activity’. This approach doesn’t distinguish systems by their being central or peripheral, but rather into ‘activity producing sub-systems’ which he called ‘layers’, each of which ‘individually connects sensing to action’:

The layers need not all use the same sensors, or activate the same degrees of freedom. In addition, not all processing is centralized. So, speaking of a mobile robot built to avoid collisions, Brooks says:

“In fact, there may well be two independent channels connecting sensing to action (one for initiating motion, and one for emergency halts), so there is no single place where "perception" delivers a representation of the world in the traditional sense.

And when layers are added, their own parochial goals can sometimes conflict over the way to use the same degree of freedom:

‘This new layer might directly access the sensors and run a different algorithm on the delivered data. The first-level autonomous system continues to run in parallel, and unaware of the existence of the second level. For example, in [3] we reported on building a first layer of control which let the Creature avoid objects and then adding a layer which instilled an activity of trying to visit distant visible places. The second layer injected commands to the motor control part of the first layer directing the robot towards the goal, but independently the first layer would cause the robot to veer away from previously unseen obstacles. The second layer monitored the progress of the Creature and sent updated motor commands, thus achieving its goal without being explicitly aware of obstacles, which had been handled by the lower level of control.”

Although Brooks makes regular references to the goals and functions of his creatures, these goals are implicit in the design of the layers, and are not internally represented:

“The purpose of the Creature is implicit in its higher-level purposes, goals or layers. There need be no explicit representation of goals that some central (or distributed) process selects from to decide what is most appropriate for the Creature to do next.” (Emphasis added.)

He’s also clear that there is competition between the behaviours. He says that  ‘each activity producing layer connects perception to action directly’, but that while an observer might impute central control, all that the creature is, is ‘a collection of competing behaviors’.

So, if Brooks is correct, even if only about a limited class of agents, then what he says poses to related challenges to the view that orderly behaviour requires a common currency:

  • He claims that there’s a way to have multiple competing goals without a proximal common currency. 
  • He claims that multiple competing goals can be handled without a final common control pathway.

(What I’ve said are two challenges clearly overlap a great deal. But there are differences of emphasis at least. Also, as I’ll explain in future postings, there is a separate ‘final common path’ argument for a proximal currency that is independent of arguments concerning other kinds of order in choice.)

I also note that what Brooks says doesn’t directly imply the denial of an ultimate currency. Indeed, Brooks positively encourages the notion that his creatures instantiate some kind of ultimate currency by frequently saying that their behavior is ‘adaptive’. He clearly doesn’t mean that they literally evolved under natural selection. But just as clearly he is saying that their behavior satisfies some condition of success (perhaps even near-optimality) at dealing with conflicting goals.

I’ll discuss some criticisms of Brooks’ position in later postings. All I’ve really tried to do here, and for now, is note why Brooks is ‘on the reading list’ for this project.

Related postings on this blog

Forthcoming attractions on this blog

Andy Clark on economic decisions
Proximal currencies can be cognitive or somatic
Ways of responding to Brooks’ challenge


Brooks, R. (1991) “Intelligence without representation.” Artificial Intelligence 47: 139-159.

[1] Put more carefully, this should say Cognitive Proximal Common Currency. (Cognitive as opposed to, inter alia, somatic. This is a distinction I’ll explain and put to work at a later date.) See Currencies can be 'ultimate' or 'proximal' and future postings on this blog.