LINGUIST List 17.1528
Wed May 17 2006
Disc: Re: Disc: Starling Study: Recursion
Editor for this issue: Ann Sawyer
Re: 17.1528317, Disc: Starling Study: Recursion
Message 1: Re: 17.1317, Disc: Starling Study: Recursion
From: Geoffrey Pullum <pullumsoe.ucsc.edu>
Subject: Re: 17.1317, Disc: Starling Study: Recursion
Tim Gentner and his colleages recently published a paper in Nature aboutlearning of artificially constructed recursive "grammars" by songbirds,with patterns like AAAABBBB (Gentner TQ, Fenn KM, Margoliash D, NusbaumHC, 2006: Recursive syntactic pattern learning by songbirds, Nature440: 1204-1207). The work has been widely reported in newspaper articles.We (Ray Jackendoff, Mark Liberman, Geoff Pullum, and Barbara Scholz) wrotea letter to Nature to warn against over-interpretation of the Gentnergroup's results. The letter presented four reasons for thinking thepaper's conclusion, that the experiment "opens a new range of complexsyntactic processing mechanisms to physiological investigation", wasnot sufficiently supported.
Within 18 hours, Nature declined to publish the letter. (In ourexperience, this is what usually happens when linguists write togeneral science journals like Nature and Science commenting on thecontent of papers with linguistic content that have been publishedby non-linguists.) Readers of the LINGUIST List might like to readhere the four points that were expressed in the letter, which wereexpressed thus:
(i) Even if it were true that starlings could grasp a recursive grammar,this could hardly provide direct evidence about the evolution of humanlanguage. It would be at best an analogous rather than homologouscapacity -- surely not an inheritance from some common ancestor ofbirds and mammals.
(ii) It is not clear that the starlings learned a recursive rule.Becoming habituated to a pattern like AAABBB does not necessarily implygrasping recursively center-embedded structures like A(A(A(...)B)B)B.This pattern could equally be detected by comparing the number of A'sand B's, given that some birds such as pigeons can subitize numbers upto 4 or more (Dehaene S, The Number Sense, Oxford University Press, 1997).
(iii) Humans do not perform well on center-embedded syntax. Even forn = 2, they are often baffled by A^nB^n structures ("People peoplecheat cheat" is all but unintelligible). Few can handle n = 3. Arestarlings outperforming humans syntactically?
(iv) Recursion is not the unique core property of the human languagefaculty anyway (Pinker S & Jackendoff R, `The faculty of language:What's special about it?', 2005, Cognition 95, 201-36). Recursion isarguably involved in comprehension of complex visual fields, planning ofaction, and understanding social environments. These human capacities areshared with other primates. Unique to human language is a very largelearned vocabulary consisting of long-term memory associations betweenmeanings and structured pronunciations plus varied phrasal syntax.
The Gentner experiment may help us understand animal pattern recognitionand learning abilities, some of them possibly prerequisites for linguisticabilities; but the implications are being considerably exaggerated,especially in popular media accounts with headlines like "SongbirdsMay Be Able to Learn Grammar."
Ray S. Jackendoff (Center for Cognitive Studies, Tufts University)
Mark Y. Liberman (Institute for Research in Cognitive Science, University of Pennsylvania)
Geoffrey K. Pullum, Barbara C. Scholz (Radcliffe Institute for Advanced Study, Harvard University)
Philosophy of Language