Last Words The Shrinking Horizons of Computational Linguistics

Understanding language is of course one of the great challenges of science, and language-related technology is one of the great opportunities of Information Technology. Consequently, many different kinds of researchers work on language issues. Within the computer science community, language is of course studied by the ‘ACL community’, by which I mean researchers who regularly publish in Association for Computational Linguistics (ACL) venues, such as Computational Linguistics journal and ACL conferences. But language-related research is also carried out by researchers in other areas of computer science, including knowledge representation, cognitive modelling, vision and robotics, and human-computer interaction communities. Of course there are even more people outside computer science who study language, including linguists, psycholinguists, philosophers, and sociolinguists. This is fine; understanding language and developing language technology are huge problems, and it is very useful to have many research communities from diverse backgrounds working on language. This will be especially true if the different research communities are aware of each other, so they can share insights, observations, problems, and so forth. Unfortunately, my impression is that the ACL community is much less interested in research in other language-related research communities than it used to be. This impression is mostly based on discussions I have had with researchers who are on the borderline between ACL and another language-research community. Several such people have toldme that while ten years ago they occasionally submitted papers to ACL venues and attended ACL conferences, now they do not bother, because they believe that the ACL community has no interest in their research. In attempt to quantify this insight, I have analysed citations from papers published in Computational Linguistics in 1995 and in 2005. More specifically, I extracted all citations from CL papers (excluding book reviews) in these years to journal papers. I then classified the cited journal papers into one of the categories shown in Table 1; whenever possible this classification was based on the subject category assigned by ISI Journal Citation Reports (JCR) to the cited journal. For example, a citation of a paper in Cognitive Sciencewould count as a psychology citation, since ISI JCR classifies Cognitive Science as ‘Psychology, Experimental’. I counted citations myself, rather than relying on ISI JCR’s count, as there were some mistakes in JCR’s counting. I also created my own ‘other NLP and speech’ classification (that is, references to speech and NLP journals other