Playing With Language in the Manual Modality: Which Motions Do Signers Gradiently Modify?

Language is traditionally characterized as an arbitrary, symbolic system, made up of discrete, categorical forms. But iconicity and gradience are pervasive in communication. For example, in spoken languages, word forms can be "played with" in iconic gradient ways by varying vowel length, pitch, or speed (e.g., "It's been a loooooooong day"). However, little is known about this process in sign languages. Here, we (1) explore gradient modification in three dimensions of motion in American Sign Language (ASL), and (2) ask whether the three dimensions are equally likely to be modified. We asked deaf signers of ASL (n = 11, mean age = 49.3) to describe an event manipulated along speed, direction, or path, and observed their use of gradient modification in lexical and depicting signs. We found that signers alter the forms of both types of signs to enhance meaning. However, the three motion dimensions were not modified equally in lexical signs, suggesting constraints on gradient modification. These constraints may be linguistic in nature, found only in signers. Alternatively, the constraints could reflect difficulties in using the hands to convey particular modifications and, if so, should be found in speakers as well as signers.