Lila Gleitman once conjectured that Empiricism, with its
associationist commitments, is innate. How else to explain its zombie like
capacity to repeatedly come back from intellectual death? One possible explanation for associationism’s
robustness is that it never returns in quite the same form. To paraphrase Mark
Twain, Empiricist history never repeats itself, but it often rhymes. I see this rhyming constantly.
Technologically, neural nets were perfectly compatible with Rationalist
sentiments (just a matter of initial weightings)[1],
nonetheless virtually all of the work done in this framework stank of
associationsism. The same holds, IMO,
for lots of recent Bayesian modeling and deep learning. There is nothing inherent in these approaches
that requires a coupling with Empiricist conceptions, but it seems that every
computational innovation seems drawn to Empiricism the way flies are to…, well
you know. It seems that we can now add
mirror neurons to the list. Why do I say
this? Because I’ve just finished reading a
terrific new book by Greg Hickock that critically reviews the mirror neuron
literature and its spiritual affinities with Behaviorism. But his book is not
merely a debunking (though don’t fret it does do a lot of that) of some bad
ideas which quickly became widely influential (another characteristic of
Empiricist fads). It is also both a nice accessible report of research on the
neuro frontier from a distinguished practitioner, and a nice case study in the
philo of science. What follows are some reasons I liked the book and why you
might find it worth dipping into.
In case you haven’t heard, mirror neurons are the
philosopher’s stones of contemporary neuro-science. Since their discovery in macaques in the late
1990s in Italy (I don't think macaques are native to Italy, just vacationing
there), they have been used to neuronally explain almost everything of
cognitive interest from language and its evolution to human empathy and autism.
What are these amazing brain mechanisms? Well, it seems that they are neurons that
fire both when the actor is acting and when the actor is watching someone else
act. They are neurons that seem part of both the motor and the conceptual
system. Or at least fire both when a monkey is reaching for something and when
s/he is watching someone else reaching for something. This has led to a robust
version of the motor theory of everything. In other words, understanding is
actually re-doing. I understand what reaching cognitively means by simulating
the reaching that I see. I understand what I hear by producing what I’ve heard.
I understand what someone is feeling, by reproducing the feeling in myself.
Talk about walking a mile in someone else’s shoes! That’s the basic idea, and
if Greg is right (and I am sure he is) this idea has really caught on.
What Greg does in the book is reveal that this simple idea
is, well, at best too simple and at worst, devoid of actual content. The
problem is not with the data: there are neurons that do what they have been
observed to do. However, the interpretation of what these firings mean has,
Greg argues, been deeply over-interpreted; over-interpreted to the point that
it is unlikely that much of a claim is being made in most cases.
All the book is great, but I particularly recommend the
sections on the role of anomalies in driving research and the terrific deflationary
section on embodied cognition, a notion that really deserves some critical
discussion, which Greg more than provides.
I’ve never understood why neuro types thought that embodied cognition
could serve as a basis for the “semantics” of action words, but it has. I would
recommend reading Greg on this and then, if you still want more, go back and
read Fodor and Pylyshyn on compositionality.
I also recommend you
take a careful look at Greg’s discussion of imitation (chapter 8) and its role
in “learning.” Here’s a short quote to give you the gist. There is
…a logical error in thinking about
imitation as the foundation for more complex capacities like theory of mind, or
that imitation itself had to evolve
to unleash a great leap forward. Maybe we should think the other way around.
Imitation is not the cause but the consequence of the evolution of human
cognitive abilities…(200)
And
For imitation to be at all useful,
you have to know what and when to imitate and you have to have the mental
machinery behind imitative behavior to put it to good use…More specifically, to
understand the role of imitation in language learning, we need to study how
language works…Or to frame it a bit differently, rather than centering our
theoretical efforts on imitation and then seeing what computational tasks
imitation might be useful for, we might center our focus on particular
computational tasks (language, understanding actions, grasping for objects) and
then see what role imitation may play…(201).
Imitation is a current refuge for associationist theories of
learning. And mirror neurons are the latest neuronal candidate for the
grounding of associationism. Greg’s
critical discussion, IMO, effectively blows up this bankrupt train of
theorizing. I’m not surprised, but I am grateful. Someone’s got to clean out
the Augean stables and Greg is very effective with a shovel.
Here’s another quote making the all too common link to
associationsism (228):
We’ve been down a similar road
before. Behaviorists had very simple mechanisms (association and reinforcement)
for explaining complex human behavior. But removing the mind as a mediator
between the environment and behavior ultimately didn’t have the required
explanatory oomph. Mirror neuron resonance theory isn’t quite behaviorism, but
there are not many degrees of separation because “it stresses… the primacy of a
“direct matching” between the observation and the execution of an action.” The
notion of “direct matching” removes the sort of operations that might normally
be thought to mediate the relation between observation and action systems…The
consequence of such a move is loss of explanatory power. The mirror neuron
direct matching claim results ina
failure to explain how mirror neurons know when to mirror in the first
place. We then have to look to the “cognitive system” for an explanation, which
lands us back where we started: with a complex mind behind the mirror neuron
curtain of explanation of complex mental functions.
As Greg notes, his critique of mirror neurons is a modern
revamping of Chomsky’s critique of Skinnerian behaviorism. Where it’s clear,
it’s clearly false and where it seems true it borders on the truistic and
vapid.
There is lots more in the book. For neophytes (e.g. me)
there is a good discussion of the dorsal and ventral systems of brain
organization (the how vs what organization of brains that Greg and David
Peoppel did so much to make part of the contemporary common neural wisdom in
the domain of language), and the various kinds of techniques that modern neuro
types use to probe brain structure. In
addition, there are lots of great examples that signal to the careful reader
that Greg is clearly a pretty good surfer and that he loves dogs.
So, if you are looking for a good popular neuro book or just
a good debunking, Greg’s book is a great place to go. Would make a marvelous Rosh
Hashanna present or a great Yom Kippur stocking stuffer.
