In a recent New York Times editorial, psychologist Gary Marcus noted that neuroscience is still awaiting a ‘bridging’ theory that elegantly connects neuroscience with psychology.
This reflects a common belief in cognitive science that there is a ‘missing law’ to be discovered that will tell us how mind and brain are linked – but it is quite possible there just isn’t one to be discovered.
Marcus, not arguing for the theory himself, describes it when he writes:
What we are really looking for is a bridge, some way of connecting two separate scientific languages — those of neuroscience and psychology.
Such bridges don’t come easily or often, maybe once in a generation, but when they do arrive, they can change everything. An example is the discovery of DNA, which allowed us to understand how genetic information could be represented and replicated in a physical structure. In one stroke, this bridge transformed biology from a mystery — in which the physical basis of life was almost entirely unknown — into a tractable if challenging set of problems, such as sequencing genes, working out the proteins that they encode and discerning the circumstances that govern their distribution in the body.
Neuroscience awaits a similar breakthrough. We know that there must be some lawful relation between assemblies of neurons and the elements of thought, but we are currently at a loss to describe those laws.
The idea of a DNA-like missing component that will allow us to connect theories of psychology and neuroscience is an attractive one, but it is equally as likely that the connection between mind and brain is more like the relationship between molecular interactions and the weather.
In this case, there is no ‘special theory’ that connects weather to molecules because different atmospheric phenomena are understood in multiple ways and across multiple models, each of which has a differing relationship to the scale at which the physical data is understood – fluid flows, as statistical models, atomic interactions and so on.
In explanatory terms, ‘psychology’ is probably a lot like the weather. The idea of their being a ‘psychological level’ is a human concept and its conceptual components won’t neatly relate to neural function in a uniform way.
Some functions will have much more direct relationships – like basic sensory information and its representation in the brain’s ‘sensotopic maps’. A good example might be how visual information in space is represented in an equivalent retinotopic map in the brain.
Other functions will have more more indirect relationships but in great part because of how we define ‘functions’. Some have very empirical definitions – take iconic memory – whereas others will be cultural or folk concepts – think vicarious embarrassment or nostalgia.
So it’s unlikely we’re going to find an all-purpose theoretical bridge to connect psychology and neuroscience. Instead, we’ll probably end up with what Kenneth Kendler calls ‘patchy reductionism’ – making pragmatic links between mind and brain where possible using a variety of theories and descriptions.
A search for a general ‘bridging theory’ may be a fruitless one.
Link to NYT piece ‘The Trouble With Brain Science’.
Mind Hacks 
I don’t know if Antonio Damasio intended to make a bridge between psychology and neuroscience in his series of books exploring the neural basis of emotion but in my mind he did. He implied that the collective expression of homeodynamic process is emotion in the physiological sense and that feeling is the conscious expression of that in the psychological sense. In other words homeostasis is the distributed organizing principal that provides biologic value to psychological and cognitive processes.
I’ve been arguing something like this for a while. Essentially a form of eliminativism. Lots of people don’t like it though because it dethrones our ideas of mind and consciousness, among other folk psychological theories, from their presumed seats of ontological primacy.
Nice metaphor. I always figured that behavior (psychology) was more like a fleeting byproduct of the brain, not really something you can put under a microscope.
But if we’re going by smallest functional “unit”, I’d say equillibrium thermodynamics would be the correct one for weather. Wow, not an easy metaphor to create!
The topic of scale is so important, Lisa Randall does a nice job in her books explaining why this is such a central concept in the life and physical sciences.
From the article:
Biology isn’t elegant the way physics appears to be (REALLY?) The living world is bursting with variety and unpredictable complexity, because biology is the product of historical accidents, with species solving problems based on happenstance that leads them down one evolutionary road rather than another.
Golly gee that sounds like a subcurrent of creationism with a side of really outdated evolutionary theory.
I suggest that reward prediction-errors are exactly the kind of bridging theory/law between psychology and neuroscience that exists already. First discovered in psychology (eg Rescorla & Wagner, 1972), and independently verified in neuroscience by Wolfram Schulz in the late 80s.
Hi,
I think this type of emergentist story still has to be odd-on favourite for the eventual solution (or dissolution) of the mind-body problem, but it’s not without difficulties (as I’m sure you realise).
The most pressing for me has to be the perceived gap when one goes from the details of the lower scale to the phenomenology of the proposed emergent one.
If we consider your example of the weather, there’s a joined-up story we can tell about how the properties of one emergent scale lead to the properties of the next, all the way up to the top. Yes, different parts of the overacrhing system “weather” emerge from multiple lower-scale systems at multiple scales, but isn’t it the case that each of these has it’s own much smaller bridge?
If so, the resultant multi-emergent, multi-system complex of interacting parts we call weather may not have a single Golden Gate Bridge over the Bay, but for sure there’s a way across, via a ramshackle system of bridges both large and small.
I’d argue the same is true for all well understood phenomena; and even less understood ones usually appear amenable to plausible speculation, with the main task being to discover the best option and fill in the details.
Conversely, the jump from matter to mind not only lacks the Golden Gate Bridge that I’d agree may not exist, but additionally any evidence for intermediary bridges in the area, or even any plausible ideas on what a bridge might look like.
Perhaps this is just our ignorance on display. But whether that ignorance is on the Bay’s shore of mind or on it’s shore of matter I think is an open question.
(…and yeah, analogy-stretching, I have no idea if the Bay has shores!)
Matt
Reblogged this on peakmemory and commented:
“Many a psychiatrist has said that he did not want to burden himself with a philosophy…but the exclusion of philosophy would…be disastrous for psychiatry.” – Karl Jaspers
Dear Vaughan,
Some people (mis)read your piece as suggesting that I (Gary Marcus) implied that we should expect some sort of “an all-purpose theoretical bridge to connect psychology and neuroscience”. To contrary, I don’t expect any such thing. As you said “there is no ‘special theory’ that connects weather to molecules”, and I both take it the same will be true for psychology’s relation to neuroscience, for precisely the reasons I pointed out: “The living world is bursting with variety and unpredictable complexity, because biology is the product of historical accidents, with species solving problems based on happenstance that leads them down one evolutionary road rather than another.” A single covering law is therefore unlikely. It is reasonable to expect a patchwork, instead.
Indeed, the one thing I said about overarching theories was that we shouldn’t expect them to be correct. To avert further misunderstanding, you might update your post.
Thanks,
Gary
Hi Gary, I have made a small change to the post to help ensure it can’t be misinterpreted.
Excellent metaphor. I like to use the one by Sydney Lamb going the other way. Looking for ‘mind’ like structures in the brain is like trying to fold the roll of toothpaste back into the tube. I wrote about it some years back on: http://metaphorhacker.net/2011/03/the-brain-is-a-bad-metaphor-for-language/