Tuesday, 23 August 2016

Philosophy, Psychology and Monkey Cognition

Hey there´s this thing called the European Society of Philosophy and Psychology which has a conference every year.  The meeting this year was  at the University of St Andrews August 10-13, 2016 (see http://espp16.wp.st-andrews.ac.uk  for the conference website). 

In fact, I happen to be the Linguistics Program chair for this society/conference and so, for my sins, I have to read abstracts, think of keynote speakers and actually attend the conference every year.  Every year, I wrench myself away from my linguistics-internal concerns and duties wondering whether I really have time for this. And every year I come away from the conference thinking  "OMG, I am so glad I made time for this”.  We  linguists should make time to engage with our colleagues over in philosophy and psychology who are thinking about the very same issues  but in radically different and yes, sometimes incompatible ways.  We can make all the noises we like about building bridges with philosophy and psychology in the abstract, but unless we talk to them and go to their conferences those bridges won´t actually get built, and misunderstandings will proliferate.  In particular, clicking on and reading the occasional hyped psychology article that catches your eye does not prepare you for the whole culture of concerns and assumptions and indeed heterogeneity of approach that you find when you are actually at one of these meetings.

This year, there was a common thread running through the conference on animal cognition and primate cognition in particular,  in part due to the invitation of Philippe Schlenker, CNRS-Institut Jean Nicod (http://www.institutnicod.org/membres/membres-permanents/schlenker-philippe/?lang=en ),  as one of the keynote speakers and to the local expertise of our hosts at St Andrews in the area of primate cognition (Check out the Centre for Social Learning and Cognitive Evolution  here https://risweb.st-andrews.ac.uk/portal/en/organisations/centre-for-social-learning--cognitive-evolution(aca65ea5-18be-4425-8477-a13cdbd890c9).html )

As we all probably know,  the field of primate cognition today is largely insensitive to the overly simplistic historical dichotomies of `innate´ vs. `learned´  that inspired linguists´ early attempts to teach chimpanzees human language (and which still fills chapters in beginner textbooks on psychology of language).   A linguist looking to sign up for the cheering gallery on one side or other of that debate will be cruelly disappointed.  So its all the more important for the responsible linguist to get up to speed on  the latest knowledge that has emerged from research in this area over the past couple of decades.

First of all, it is quite convincing from the research that the great apes communicate intentionally, do social learning, use tools, have problem-solving abilities and even some hallmarks of theory of mind.  The whole issue of intention to communicate, as  tested and proved by a number of researchers, requires  at least some sort of recognition that others possess minds, and that the state of their knowledge can be affected by one´s own communicative actions (I am thinking here of papers I heard by Christine Sievers (https://philsem.unibas.ch/seminar/personen/sievers) and Thibaud Gruber (https://www2.unine.ch/compcog/thibaud_gruber) , and also Katie Slocombe´s (https://www.york.ac.uk/psychology/staff/faculty/ks553/) contribution in the invited symposium).  So the interesting question is whether there is some sort of basic groundfloor `theory of mind´ such that apes and very young children can have that, but not  the fullblown version that would allow them to pass the standard false belief test.   If there is an intermediate version, is it distinguished from the full version because:

-It ascribes knowledge to other minds rather than belief (as Jennifer Nagel was arguing http://individual.utoronto.ca/jnagel/Home_Page.html )

-It is expressive rather than genuinely perspective shifting (as Dorit Bar-On suggested http://www.doritbar-on.com )?;
-It is one-step rather than recursively specular in the way it takes other minds into account?

Are any of these distinctions themselves correlated with any of the others, or indeed with the the special linguistic capacities for syntax?

In Schlenker’s keynote address that kicked off the conference, he described in detail the sign system employed by a number of groups of monkeys and attempted to describe the truth conditions for each individual sign in a systematic way.  Schlenker was scrupulous in staying away from questions of whether we should call such systems `language’  or not, preferring rather be specific about how it seems that this particular system is working.  The interesting aspect of his proposal for the meanings deployed in the system is that they seem to involve a kind of blocking, where the informationally more specific sign blocks the use of the more general one.  If this kind of informational pragmatic choice guides the deployment of signs in monkey communities, it seems to point to at a least a limited theory of mind. Schlenker himself, in ascribing pragmatic competence to monkey groups, stopped short of claiming that they needed to possess full specular theory of mind of the kind that is assumed to lie behind our competences in standard forms of Gricean reasoning.   But if this limited kind of pragmatic effect can be seen even in these simple systems, with rudimentary acknowledgement of audience then it is important both for studies of the evolution of theory of mind, and for the architecture of the language faculty. (If you are interested in the details, see the recent issue of Theoretical Linguistics devoted to Formal Monkey Semantics for a target article written by Schlenker and his research group, with commentaries by various linguists and cognitive scientists http://www.degruyter.com/view/j/thli.2016.42.issue-1-2/issue-files/thli.2016.42.issue-1-2.xml )

What does it mean that monkeys seem to have systems that are best described via informational blocking (maxim of quantity).  Full Gricean reasoning probably involves infinite specular regress, but certain facts with respect to informational computation do not seem to require that degree of sophistication.   It can be shown that great apes exist in social groups and utilize their gestures and vocalizations intentionally with an aim to express or convey information.  But surely one can intend to warn others without having full blown theory of mind?  Some acts of expression can be purely reflexive in the sense of not being under conscious control, but it can be shown that at least some ape gestures/vocalizations are not of this type.  And pragmatic effects can only arise in the context of an audience. So there must be different levels of pragmatics corresponding to different levels of sophistication with respect to how we represent other minds.

Andrew Whiten from St Andrews gave the final keynote of the conference and he talked about the work that his group has been doing on cultural transmission within primate communities.  With respect to being social animals with socially transmitted traditions, chimps once again seem to have some restricted version of what we see in humans.  In fact, Whiten would argue that the differences we find here are slight indeed.  Chimps use tools and pass on use of those tools, as well as certain non-necessary ways of doing things to the group. Groups of chimps also seem to have a strong instinct for social conformity within the group.  Chimps are good at imitating and are rational problem solvers/learners.  Unlike the claims of the Tomasello group, the Whiten group in St Andrews has been successful in showing that chimps do have imitative and  social instincts--- they are not just emulators. (Tomasello’s group had a hypothesis to the effect that chimps merely tried to emulate `goals’  of actions they perceive others doing where that goal is attractive to them, but are sloppy about the detail when copying the means by which the emulated being is bringing about those goals. So for the Tomasello group apes were not genuine imitators in our sense.)

In fact, it can be shown that these cousins of ours, the great apes, are actually qualitatively better imitators than other monkeys.  (Ironically then, there is actually no generalized `monkey see, monkey do’, but a restricted version of that is found specifically within the great apes.)  Chimps can be taught a version of the Simon Says game (for a reward) very quickly for example, but not capuchin monkeys who are otherwise pretty smart.   But the Tomasello group is partly right too.  In experiments where a certain goal is achieved by a sequence of actions, a chimp will copy the actions to achieve the goal. But if it becomes manifest to the chimp that some of the steps are not practically necessary to the observed outcome, the chimp will miss out these steps.  Young children however, will systematically continue to repeat the useless elaborative steps, even after it has been made manifest that they do not contribute to the outcome.  This the phenomenon that is now known as `over-imitation’. They were initially discovered by the Whiten group, and have been robustly replicated.  

But maybe children are less rational at this age than the chimps, or less able to calculate physical outcomes, so they are just playing it safe?  Or maybe  both children and human adults in an experimental situation see the task as a kind of game which leads them to over imitate?  In an interesting new extension of the paradigm, the Whiten group ran a similar experiment with adults in a non-experimental situation.   They set up the same primate-tested tasks as part of a hands-on installation at Edinburgh zoo, inviting adults passing through the exhibit to `have a go’  at the tasks that had been tested on primates. The adults could watch the training video (the different conditions were cycled) and then attempt the same task on the actual equipment.  Importantly, the human adults did not know they were even being observed, although they were in fact being filmed.  Once they did the task, an experimenter came up to them and explained `candid camera’  style, asking if they were willing to sign a consent form for their data to be used (they usually did).  The amazing upshot of the study was that the unobserved fully rational adults also did the full detail imitation  even when they could judge that those extra bells and whistles had no effect on the outcome! Recall that the chimps in the same situation left out the extra bits and went straight for the prize. 

Now who would have thought that there would be so much interesting difference in the realm of imitation?  Imitation, we are told in LING 101  is the thing that language acquisition is not  about.  For good reason, since imitation alone is totally inadequate to the task. In particular, overexuberant imitation of everything would be a hopelessly huge task and would actually inhibit pattern discovery (in the jargon, compulsive imitation is not the same as over-imitation).   There needs to be selective attendance to certain aspects of what the young human is exposed to. But that is not all, I would argue.  Over and above that, the evidence seems to be that humans in certain domains attend and imitate in an overly fine-grained way, in a way that does not need to be justified by immediate practical goals.

Another difference in the imitative capacity between us and chimps, is called `ratcheting’, and I think it actually might be related to the first.  Children can easily be taught to build one learned behaviour on top of another one.   If you try to do this with chimps, they get stuck at the first stage.   Now, if you try to teach them the same sequence of actions but to a single final goal, they are capable of that, so its not the memory or extended nature of the task that is hard.  Things go wrong if you teach a chimp a behaviour that achieves a certain goal, and then, a while after they have learned that behaviour, try to teach them to suspend goal number one and use the first behaviour as a stepping stone  add a new behaviour and achieve an even bigger payoff.  Chimps should in principle be rational enough to see the advantage of this but in fact, according to Whiten, they get stuck.  No ratcheting (this is apparently the technical term but I might be spelling it wrong).   This for the Whiten team is the reason that chimp culture does not undergo cumulative advance, unlike our own.  But the discussion of the no ratcheting discovery started me thinking about how this could also be related to the acquisition of language.

Rational and goal oriented emulation like the chimps generally do ends up as low fidelity copying--- you concentrate on the outcome and try to reproduce that. 
But arbitrary and causally more opaque tasks (or tasks with non transparent or deferred payoffs) are hard to acquire if you are a goal-oriented learner.  

But what if you just take pleasure from your success at high fidelity imitation with no need of reward?  What if we humans have an instinct for learning just for the fun of it (within certain targeted domains of course, that we are predisposed to pay attention to) ?   Learning for the sake of it, non-goal oriented learning, is actually something that distinguishes us from our great ape cousins.  That would explain both the rachetting and the overimitation.  Learning is not a rational strategy for us the way it is for chimps. We get rewards just from the success of learning itself. Arguably both rachetting and overimitation are important for learning language. Overimitation because very fine grained motor imitations are necessary to start producing the differentiation in the produced code that language requires, even in the absence of immediate rewards. Ratcheting because we need to be able to build up our skills cumulatively and build hierarchical complexity in the symbolic system.  Recursion at the symbolic level requires that one can use one result as a stepping stone to the next.  The very thing that the chimps get stuck on. (Now there may be evidence that chimps use recursive reasoning in problem solving tasks, or in their vision systems like us, or whatever, but what we are talking about here is symbolic manipulation, which is crucially  mediated by learning.)  So one hypothesis might be that it is narrowly goal-oriented learning vs. and instinctive joy of imitation that is one of the crucial ingredients in what makes us special. (This latter aspect on the other hand, we seem to share with some birds).

Back to Tomasello. Tomasello’s big idea about what makes humans unique is the complexity and richness of our social structures (http://www.eva.mpg.de/psycho/staff/tomas/pdf/Tomasello_EJSP_2014.pdf ).
However, my own hunch from the research of the Whiten group and others  is that what we are seeing in chimps with respect to social structures is a difference in degree not in kind, and certainly not drastic enough to underpin the huge cognitive leap to language.  If so, then we need to look elsewhere for the crucial cognitive ingredient in my opinion. One could speculate about a kind of genetic switch that suddenly allowed recursion. But what would that be? Suppose the key is in the non-goal orientedness of the learning mechanism, which creates both high fidelity and ratcheting?

Thinking about it this way makes a nonsense of the old dichotomies of nature vs. nurture by the way---  the thing that is innate and distinctive is a way of learning. (The more we know about nature and nurture from the geneticists anyway the more those two things get blurred.)

At any rate, that is just a flavour of the ideas floating around the conference and my own thoughts on hearing them. To be clear, none of the speculations and ramblings opined in this piece would be endorsed by those real psychologists and philosophers out there, but they certainly provoked me to think them.  I can only hope my short description inspires other linguists to attend this kind of meeting in future.  The next ESPP takes place at the University of Hertfordshire. Watch this space !