Recursion in severe aphasia.

Zimmerer, V.C., & Varley, R.A. (2010). Recursion in severe aphasia. In H. van der Hulst (Ed.): Recursion and human language. Berlin: Mouton de Gruyter, 393-406.

The volume is the result from the first conference on recursion in language hosted by the fascinating Dan Everett at Illinois State University in 2006. About a hundred people got together trying to figure out what Hauser, Chomsky and Fitch were talking about in their seminal, but pretty vague Science paper. It was great fun. It was followed by another conference at UMass in Amherst which, while stimulating, made us freeze much of the time. The organizers did not manage to switch off the air conditioning in the building and had to distribute blankets. If a group of shipwrecked survivors decided to pass their time with Powerpoint, this was how it would look like.

The term recursion as we use it comes from computer theory, where it can take many meanings. The specific meaning in language sciences is the mental ability to "embed" one representation within another. In language we can embed sentences (e.g. [Peter thinks that [Mary believes that [George likes ice cream]]]) and phrases ([My mother's [friend's [son]]]). Recursion seems needed to explain language, and people like Noam Chomsky see it at the core of human cognition. Others have said that language is needed for recursion, so whenever we need recursion elsewhere (for example in maths or social cognition) we need to use language.

We looked at evidence to see whether in people with very severe language disorder, recursion is intact. It is, as shown is several experiments we review. The evidence suggests that language is not needed for recursion, and we make a suggestions for alternative views. I still agree with this article's main message, but today I would present some aspects differently.