PSYCHOLOGICAL AND COGNITIVE SCIENCES Correction for “Large-scale evidence of dependency length minimization in 37 languages,” by Richard Futrell, Kyle Mahowald, and Edward Gibson, which appeared in issue 33, August 18, 2015, of Proc Natl Acad Sci USA (112:10336–10341; first published August 3, 2015; 10.1073/pnas.1502134112).
The authors note that five references were inadvertently omitted from the published article. The complete references appear below.
The following statement citing the omitted ref. 43 should be added at the end of the first full paragraph on the right column of page 10337: “Liu (43) provides corpus evidence from 20 languages showing that natural language dependency trees have shorter dependency length than random ordered trees of the same length. This finding is compatible with the general hypothesis that language users prefer utterances that have short dependencies, and is compatible many mechanisms to accomplish this, including non-syntactic mechanisms. For example, language users might structure discourse (splitting ideas into multiple sentences), drop optional syntactic elements such as pronouns, or choose favorable word orders. Our work aims to show specifically that languages and language users universally prefer word orders that minimize dependency length, given the dependency tree structures of the sentences they want to express.”
Citations to refs. 44–47 should be added on page 10336, second full paragraph, line 4, following the sentence that ends “...heads are words that license the presence of other words (dependents) modifying them.”
43. Liu H (2008) Dependency distance as a metric of language comprehension difficulty. J Cogn Sci 9(2):159–191.
44. Tesnière L (1959) Eléments de syntaxe structural (Libraire Klincksieck, Paris), [Elements of structural syntax].
45. Hayes DG (1964) Dependency theory: A formalism and some observations. Language 40(4):511–525.
46. Hudson RA (1984) Word Grammar (Blackwell, Oxford).
47. Mel’čuk I (1988) Dependency Syntax: Theory and Practice (The SUNY Press, Albany, NY).