The Origins of Arbitrariness in Language

The Origins of Arbitrariness in Language Michael Gasser (gasser@indiana.edu) Computer Science Department; Lindley Hall 215 Indiana University; Bloomington, IN 47405 USA Abstract of noise added to both the form and the meaning. Two constraints that you need to consider in your design are ease of learning and ease of storage. Each user has fi- nite resources for learning and storage, and there is an advantage to languages that are learned with fewer pre- sentations. The main issue of concern in this paper is how the solution to a language design task of this type is con- strained by the number of distinct meanings that are to be conveyed by the language. I will argue that there are advantages to languages with systematic relation- ships between forms and meanings and advantages to languages without such systematicity. I will then discuss how competitive learning fares at learning both types of languages. Finally I will discuss the implications for ac- quisition and evolution of human language. Human language exhibits mainly arbitrary relationships between the forms and meanings of words. Why would this be so? In this paper I argue that arbitrariness be- comes necessary as the number of words increases. I also discuss the effectiveness of competitive learning for acquiring lexicons that are arbitrary in this sense. Fi- nally, I consider some implications of this perspective for arbitrariness and iconicity in language acquisition. A Language Design Task Imagine you are inventing a language. It should asso- ciate signals (“forms”) that can be produced and per- ceived by the users of the language with perceptual or motor categories (“meanings”). Assume that both forms and meanings are patterns of values across sets of dimen- sions and that you have been given the form and meaning dimensions. Assume further that the specific design task includes a set of meaning categories that need to get reli- ably conveyed. That is, given a particular pattern across the meaning dimensions, if it belongs to one of the given set of categories, a user who knows the language should be able to assign a form to it, that is, an appropriate pat- tern across the set of form dimensions. Similarly, given a pattern across the form dimensions, if it belongs to one of the set of form categories that you have built into your language, a user who knows the language should be able to assign a meaning to it. Furthermore, the form assigned to an input meaning should be the “right” form; that is, the form that gets output should pass the com- prehension test in the reverse direction. Providing this form to a user who knows the language should result in an output meaning that is at least closer to the original meaning than to any of the other meaning categories. In the same fashion, the meaning assigned to an input form should pass the production test in the reverse direction. 1 Your language is not hard-wired into a user; it must be learned through a series of presentations. A presentation consists of a pairing of a form and a meaning selected randomly from the set of possible form-meaning pairs that are built into the language, with a small amount Iconicity and Arbitrariness How Iconicity Can Help Learning the association between forms and meanings can be facilitated if there is a systematic relationship be- tween the patterns. A simple example of such a relation- ship is a correlation between the values on a form dimen- sion and a meaning dimension. There are two possibili- ties for where such a correlation might come from. One is for it to be based on a natural relationship between the two dimensions, for example, if they are the same di- mension at a more abstract level. Such relationships are familiar in human language from onomatopoeia, in which form imitates meaning on one or more acoustic/auditory dimensions, for example, pitch. Examples of this type are more common in sign languages, where a movement of the hand in signing space may represent a physical movement of some object in meaning space. A further possibility is for the relationship between the correlating dimensions to be completely arbitrary, or at least opaque to the users. In some sign languages, for example, American Sign Language and Japanese Sign Language, movement towards or away from the head represents the gain or loss of knowledge: learning, re- membering, forgetting. But the motivation for the asso- ciation between the form and meaning dimensions in this case would require that the user know that knowledge is in some sense in the head. Thus the relationship between the form and meaning dimensions in this case could be viewed as arbitrary by a particular learner, though the learner might still notice the systematicity of the rela- Note that in this sense, these simple languages deviate from human languages, which permit multiple forms for the same meaning and multiple meanings for the same form. But the constraint has to roughly hold for communication to get off the ground, and young children learning language seem to behave as though it does (Markman, 1989).