LINGUIST List 17.1553
Sun May 21 2006
Disc: Re: Disc: Starling Study: Recursion
Editor for this issue: Ann Sawyer
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1. John
Limber,
Re: Disc: Starling Study: Recursion
Message 1: Re: Disc: Starling Study: Recursion
Date: 19-May-2006
From: John Limber <John.Limberunh.edu>
Subject: Re: Disc: Starling Study: Recursion
The sentiments of Geoffrey Pullum and others (see Discussion item http://linguistlist.org/issues/17/17-1528.html) are similar to my own expressed to a different discussion group in regard to Gary F. Marcus' (Nature 2006 440:1117) overview to Genter et al (2006).
*** Professor Marcus is quite, shall I say generous, in his attribution of recursion to these birds. My own bet is that they've cleverly learned to count up to four and match to successive samples -- a capability long suspected in corvids and other species.
(This, by the way, is a non-trivial accomplishment-- humans probably can't do very much better without conscious counting. See Koehler, O. (1956). The ability of birds to 'count'. In J. R. Newman (Ed.), The world of mathematics (pp. 489-496). New York: Simon and Schuster.)
For example, if presented aabb, they see aa and respond positively if the following stimulus, bb, is of the same number, two. Marcus certainly knows that recursion is a theoretical concept enabling generation of an infinite set from a finite set of rules -- not something one can see.
Yet in this study only a small subset of 'sentence' strings is actually used. Why then would anyone want to 'generalize' from performance on a very small n, up to four, to the infinitely large number implied by 'recursive?'
The motivation for ascribing recursion to English is based on a number of considerations -- including the reasonable but theoretical idea that any limit on 'depth' of recursion (magnitude of n in AnBn below) is a matter of memory and not a fact of English. Another assumption is that the same lexical, phonological, syntactic and semantic processes are used in clauses whether n=1, 2, 3, 4,....43... 1176... In any case, attribution of recursion in human language is hardly based on observing an infinity of sentences.
Getting back to the starlings -- none of these sentence processing issues ever arise and we seem to have a possible pre-existing alternative explanation of their behavior -- successive match-to-sample. Perhaps we should be less generous in our interpretation of these data as demonstrating recursion?
Koehler himself thought birds' numerical skills might be relevant to the understanding of language evolution; Genter et al (2006) still might have something useful to contribute on this issue but I don't see it yet.
(This piece of research provides an amusing counterpoint to the recent claim (which I haven't read yet) that the Amazonian Piraha language is not recursive! The notion of 'recursion' seems to have gone beyond its mathematical or linguistic significance into the realm of language politics.)
****** The experience Jackendoff, Pullem et al had with Nature only supports my belief on this latter point. -- John Limber Durham, NH
Linguistic Field(s): Language Acquisition Philosophy of Language
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