Do Neurons Literally Have Preferences?

Carrie Figdor has been arguing that they do.

Consider these sentences, drawn from influential works of neuroscience (quoted in Figdor forthcoming, p. 2):

A resonator neuron prefers inputs having frequencies that resonate with the frequency of its subthreshold oscillations (Izhikevich 2007).

In preferring a slit specific in width and orientation this cell [with a complex receptive field] resembled certain cells with simple fields (Hubel and Wiesel 1962, p. 115).

It is the response properties of the last class of units [of cells recorded via electrodes implanted in a rat’s dorsal hippocampus] which has led us to postulate that the rat’s hippocampus functions as a spatial map. ... These 8 units then appear to have preferred spatial orientations (O’Keefe and Dostrovsky 1971, p. 172).

These are completely standard, unremarkable claims of the type that neuroscientists have been making for decades. Figdor suggests that it's best to interpret these claims as literal truths. The verbs in these sentences work like many other verbs do -- "twist", "crawl", "touch" -- with literal usage across a wide range of domains, including organic and inorganic, part and whole.

Figdor's view sounds bizarre, perhaps. People literally have preferences. And rats. Maybe frogs. Not trees (despite 22,000 Google hits for "trees prefer", such as "Ash trees prefer moist, well-draining soil for optimum growth"). Definitely not neurons, most people would say.

One natural way to object to Figdor's view is to suggest that the language of neurons "preferring" is metaphorical rather than literal. I can see how that might be an attractive first thought. Another possibility worth considering is that maybe there are two senses of "prefer" at work -- a high-grade one for human beings, a thin one for neurons.

Figdor responds to these objections, in part, with technical linguistic arguments that I am insufficiently schooled in linguistics to evaluate. Does conjoining human and neuronal cases of "prefers" pass the zeugma test?

However, from seeing others' reactions to Figdor -- she gave a talk here at UCR a couple weeks ago -- I'd say it's not a fine sense of technical linguistics that drives most people's rejection of Figdor's claim. (In conversation, she says agrees with me about this; and in newer work in progress she is de-emphasizing the technical linguistic aspects to focus on the bigger picture, including how terms evolve over time in deference to scientific usage.) What gives folks the heebie-jeebies is the thought that "preferring" is a psychological notion, and so if Figdor is saying that neurons literally have preferences, she appears to be saying that neurons literally have minds or psychological states. And we certainly don't want to say that! (Do we?)

Figdor is not some far-out panpsychist who believes that neurons tingle with experiences of delight when they receive the stimuli they prefer. But she is far out in another way -- a more sensible and appealing way, perhaps. Once we see the actual source of her radicalism, we can start to appreciate the importance and appeal of her work.

It's natural -- common sense -- for us to approach the world by dividing it into things with minds (you, me, other people, dogs, birds...) and things without minds (stones, trees, pencils, fingernails). Reflecting on intermediate cases, such as various types of worms, one might sense trouble for a sharp distinction here, but vagueness along a single spectrum of mindedness isn't too threatening to common sense. The essential difference between the minded and the un-minded remains, despite a gray zone.

Figdor's picture challenges all that. If what she says about "prefer" also goes for some other important psychological terms (as she thinks it does), then mentality spreads wide into the world. Some psychological terms -- "prefer", "decide", and "habituate" are her examples, to which I might add "seek", "learn", "reject", and many others -- appear to spread wide; while other terms, such as "meditate", "confess", and "appreciate", might apply only to humans (or maybe a few other species). Each psychological term has a range of application, and the terms that are more liberally applicable will attach to all sorts of systems that we might not otherwise tend to regard as privileged with any sort of mentality.

Figdor has taken, I think, a crucial step toward jettisoning the remnants of the traditional dualist view of us as imbued with special immaterial souls -- toward instead seeing ourselves as only complex material patterns whose kin are other complex patterns, whether those patterns appear in other mammals, or in coral, or inside our organs, or in social groups or ecosystems or swirling eddies. Some complexities we share and others we do not. That is the radical lesson of materialism, which we do not fully grasp if we insist on saying "here are the minds and here are the non-minds", demanding a separate set of verbs for each, with truly "mental" processes only occurring in certain privileged spaces.

With that thought in mind, let's go back to "prefer". Do neurons literally prefer? I don't know whether the linguistic evidence will ultimately support Figdor on this particular case, but I think we can approach it evenhandedly, letting fall wherever they may the technical tests of metaphor and polysemy and other considerations from linguistics and philosophy of language -- figuring that of course some of our mental state verbs literally refer to patterns of behavior that spread widely, and at different spatiotemporal grain, across the complex, multi-layered, dynamically evolving structures of our world.

[image source]

--------------------------------------

Carrie writes:

Thanks to Eric for posting on my work-in-progress and the opportunity to clarify a few things. First, the technical linguistic stuff is actually my attempt to understand why it could possibly strike anyone as "natural" or "reasonable" to think these uses are metaphorical. Who "naturally" thought Hubel and Wiesel intended their descriptions of their data to be metaphorical? To the contrary, the cry of "Metaphor!" reflects not an astute semantic analysis of their uses but an automatic response to my claim that they should be interpreted literally: "They just can’t possibly be literal." The idea that they are metaphorical is actually one of the weakest semantic alternatives to a literal view.

That said, Eric is correct that I am not a radical panpsychist. Rather, I’m interested in a plausible, non-ad hoc explanation of the ever-expanding uses of psychological language throughout biology at all levels of complexity. Basically, I think psychological concepts are transitioning to scientifically determined standards for proper use, leaving behind the ideal-rational-human, anthropocentric standards we now have. There’s a lot more to that story, and I hope to make it public very soon.