Culture Magazine

Computation in Language, Turing Machine Edition

By Bbenzon @bbenzon
Continuing on....
So, I’m exploring the idea that language is the simplest thing humans do that involves computation. Thus, in my current view, whatever it is that goes on in the brain of a chimpanzee, a chameleon, or a roundworm, for example, it isn’t computation. Just what it is, that’s not my concern at this point. It follows as well that linguistic computation is grounded in something else, likely several things, none of which are my direct concern here. To be clear on this point, I reject the view the individual neurons are the basic elements of mental computation as was suggested by McCulloch and Pitts 1943, “A logical calculus of the ideas immanent in nervous activity.” Of course neurons and neuronal circuits can be simulated by a computer, but that’s something else. Computers can simulated atomic explosions too, but we don’t take that as evidence that atomic explosions are computational phenomena.
But what do I mean by computation? I mean a Turing machine, albeit one of somewhat limited capacity. As language is first of all speaking, that’s where we start. The vocal system writes to the tape while the auditory system reads from it; taken together they are the head of the device. The brain contains that table of instructions – I’m indifferent at this point as to whether those instructions are symbolic, pre-symbolic, or both – and the state register. The speech stream itself is the tape.
Therein lies the limitation of this Turing machine. In standard Turing machines the tape can move over the head in either direction. This “tape” moves in only one direction. The tape in a universal Turing machine in indefinitely long. This tape is quite limited in length. Experiments on the length of short-term memory put it at about 3 to 4 seconds. That’s the length of this one-directional tape. It can carry a single line of poetry.
Those limitations gives this Turing device the character of a very specialized input-output system. It’s a way, of course, for people to exchange symbolic “information” with one another, sending outputs to others and receiving inputs from them. Most interstingly, and very curiously, it allows us to exchange inputs and outputs with ourselves in ways otherwise impossible. Just why and how that is so is something I’ve thought about a great deal over the years, but do not understand. And don’t think I’ll get there now. But I note it.
Rather than go on and on I’ll conclude with a passage about the poetic line from my 2003 paper, “Kubla Khan” and the Embodied Mind. Note, in particular, the few lines about syntax and its relation to semantics:
Considered as a unit of analysis, the line is a conjunction of units of thought, or sense, and units of physical realization – speaking and hearing.
The significance of the poetic line is easily demonstrated by the common experiment of taking some fragment of ordinary prose and breaking it into separate lines. The result is rarely good poetry, but the poetry-like presentation invites one to consider each line as a unit by itself in addition to its connections with the lines before and after. The quasi-autonomy of the poetic line belongs to the cultural conventions governing how we read poetry. The psychological, not to mention the neural, underpinnings of this effect are, as far as I know, obscure.
Nonetheless, the linguist Wallace Chafe has quite a bit to say about what he calls an intonation unit, and that seems germane to any consideration of the poetic line. In Discourse, Consciousness, and Time Chafe asserts that the intonation unit is “a unit of mental and linguistic processing” (Chafe 1994, pp. 55 ff. 290 ff.). He begins developing the notion by discussing breathing and speech (p. 57): “Anyone who listens objectively to speech will quickly notice that is not produced in a continuous, uninterrupted flow but in spurts. This quality of language is, among other things, a biological necessity.” He goes on to observe that “this physiological requirement operates in happy synchrony with some basic functional segmentations of discourse,” namely “that each intonation unit verbalizes the information active in the speaker’s mind at its onset” (p. 63).
While it is not obvious to me just what Chafe means here, I offer a crude analogy to indicate what I understand to be the case. Speaking is a bit like fishing; you toss the line in expectation of catching a fish. But you do not really know what you will hook. Sometimes you get a fish, but you may also get nothing, or an old rubber boot. In this analogy, syntax is like tossing the line while semantics is reeling in the fish, or the boot. The syntactic toss is made with respect to your current position in the discourse (i.e. the current state of the system). You are seeking a certain kind of meaning in relation to where you are now.
Chafe identifies three different kinds of intonation units. Substantive units tend to be roughly five words long on average and, as the term suggests, present the substance of one’s thought. Regulatory units are generally a word or so long (e.g. and then, maybe, mhm, oh, and so forth), and serve to regulate the flow of ideas, rather than to present their substance. Given these durations, a single line of poetry can readily encompass a substantive unit or both a substantive and a regulatory unit.
The third kind of unit, fragmentary, results when one of the other types is aborted in mid-execution. That is to say, one is always listening to one’s own speech and is never quite sure, at the outset of a phrase, whether or not one’s toss of the syntactic line will reel-in the right fish. If things do not go as intended, the phrase may be aborted. Fragments do not concern us, as we are dealing with a text that has been thought-out and, presumably, edited, rather than with free speech, which is what Chafe studied.
Chafe’s notion is consistent with an observation made initially by Ernst Pöppel. After reviewing studies by others and offering some of his own, Pöppel concluded that our awareness of the present extends roughly three to four seconds. That suggested that lines of poetry last no longer than that and that, where written lines appeared to take longer to read, they have a strong break in the middle. Working with a poet and critic, Frederick Turner, Pöppel found evidence for these notions in the poetry of several cultures, thus showing how versification technique deals with this constraint (cf. Turner and Pöppel 1983, Pöppel 1985, pp. 75-82).

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