A merican S ign L anguage Handshapes Reflect Pressures for Communicative Efficiency (2024)

Abstract: Communicative efficiency is a key topic in linguistics and cognitive psychology, with many studies demonstrating how the pressure to communicate with minimal effort guides the form of natural language. However, this phenomenon is rarely explored in signed languages. This paper shows how handshapes in American Sign Language (ASL) reflect these efficiency pressures and provides new evidence of communicative efficiency in the visual-gestural modality.We focus on hand configurations in native ASL signs and signs borrowed from English to compare efficiency pressures from both ASL and English usage. First, we develop new methodologies to quantify the articulatory effort needed to produce handshapes and the perceptual effort required to recognize them. Then, we analyze correlations between communicative effort and usage statistics in ASL or English. Our findings reveal that frequent ASL handshapes are easier to produce and that pressures for communicative efficiency mostly come from ASL usage, rather than from English lexical borrowing.

## introduction there is increasing evidence suggesting that human languages adapt to the needs of their users by minimizing the effort required by the sender and receiver to achieve successful communication. it is argued that natural languages tend to find an optimal balance between the efforts of the two participants when they are at odds with each other @xcite @xcite @xcite . while the majority of existing work studying communicative efficiency has focused on spoken languages, recent results have provided evidence that signed languages are also shaped by drives for efficient communication in the visual-gestural modality. for example, @xcite found that casual signing prioritizes moving fewer, more distal joints, increasing articulatory ease. @xcite found that rare hand configurations are produced close to the signer's face, increasing perceptual ease. this paper further explores communicative pressures on visual signed languages by focusing on american sign language (asl) handshapes. handshapes refer to distinctive configurations of the hand and fingers, and are one of the five fundamental parameters characterizing signs in asl ( §2.1). a finite set of handshapes is combined with different movements, locations, palm orientations, and non-manual markers to express various asl signs. figure 1 shows example handshapes, some of which are used only in native asl signs (left), some of which are used only in asl signs borrowed from other languages (right), and some of which are used in both contexts (center). we investigated evidence of communicative efficiency in both the native and foreign components of asl. foreign signs are borrowed from other languages in contrast to native signs that are inherently derived from asl itself. 3 the foreign component of asl includes neutral fingerspelling where english words are spelled out using one-handed signs that each represent a letter of the english alphabet ( §2.2); loan signs where commonly fingerspelled words evolved into a lexicalized sign; and initialized signs that are produced using the handshape of the first letter of its english translation. figure 2 : asl fingerspelling letters from @xcite . for certain letters, the palm is oriented differently than in practice to better illustrate the handshape. to compare effects of asl and english usage on handshape efficiency, we focused on fingerspelling handshapes (fs handshapes; figure 2 ) since 19 out of 22 fs handshapes appear in both the native and foreign components. we were motivated by the following research questions: rq1 do handshapes reflect pressure for communicative efficiency? rq2 is pressure for efficiency mostly or all from 3 although signs originating from lexical borrowing are technically a part of asl, we refer to them as the "foreign" component for our purposes, following @xcite . the foreign component of asl includes signs borrowed from english as well as signs borrowed from other signed languages (e.g. country signs such as japan, china). in this paper, we only address foreign signs that derive from english. ## data we describe the data we use to compute usage statistics in asl and english, as well as to compute the articulatory and perceptual effort in asl handshapes. ## methodology we now describe our methodology to measure usage metrics in asl and english, and articulatory/perceptual effort in handshapes. ## analysis to analyze the effects of articulatory and perceptual effort on asl handshapes, we computed effort scores for each handshape in our dataset. since our dataset contains several samples of each letter, and the number of samples is not constant across letters, for each letter we took the mean of the effort scores across samples. then, we computed pearson's correlation coefficient between effort scores and usage statistics using scipy @xcite . we report and visualize correlations in figure 5 . we summarize the three predictions we proposed in §1, following from our hypothesis that handshapes reflect pressure for communicative efficiency from asl usage, but not from english usage: p1 fs handshapes that appear frequently in native asl signs are easier to produce. p2 letters that appear frequently in english are not necessarily easier to sign in asl fingerspelling. p3 letters that appear in similar contexts in english are not necessarily easier to disambiguate from one another in asl fingerspelling. ## discussion revisiting our initial research questions, to answer rq1, we found evidence for communicative efficiency in asl handshapes, where frequent handshapes are easier to produce in native asl signs. to answer rq2, we did not find evidence of communicative efficiency in handshapes of foreign signs derived from english. pressures for com-municative efficiency are mostly driven by asl usage rather than english usage. there are a few possible explanations for this asymmetry between english and asl pressures for efficiency. first, @xcite demonstrated that foreign components of asl obey fewer of the phonological constraints observed in the native component of asl. since fingerspelling and other foreign vocabulary lie at the periphery of the asl lexicon, they may be less subject to the pressures for communicative efficiency that shape the native lexicon. second, the asl fingerspelling system traces its origin to the invention of hearing educators @xcite , whereas native asl signs evolve and diversify naturally through use by @xcite . this may lead to asl signs being more likely to adopt linguistic forms that optimize communicative efficiency. finally, asl fingerspelling is relatively infrequent in signing discourse compared to native signs, constituting somewhere between 12 and 35% of produced signs @xcite . studies on phonological change in spoken languages have shown that frequently used words undergo faster language change @xcite . @xcite has also found that asl signs observe similar effects, where more frequent signs reflect more optimization. articulatory ease might play a stronger role in native asl signs because of the latter's frequency of use. ## related work relatively few works have examined theories of communicative efficiency in visual signed languages compared to studies on efficiency in spoken languages. @xcite studied handshapes in taiwanese sign language (tsl) by manually categorizing tsl handshapes into three classes of articulatory ease, and found that more frequent handshapes are easier to articulate. we extended this analysis of the relation between articulatory effort and handshape frequency by designing an automatic way to quantify articulatory effort. napoli et al. (2011) studied efficiency pressures in asl signing in casual conversations. they found that casual signing has a tendency for distalization, where it favors movement in arm and hand joints more distant from the torso than closer to the torso, presumably since moving a distal joint requires less energy than a joint close to the torso. we further investigated efficiency pressures on articulatory effort by studying handshape configurations rather than movements, and focusing on finger articulations in the dominant hand, rather than arm and hand joints. caselli et al. ( 2022 ) compared the lexical frequency and handshape probability of 2000 lexical items in asl to the location of articulation, and they found that signs with rare handshapes are signed closer to the face than signs with common handshapes, which optimizes perceptual ease since rare handshapes that are presumably harder to recognize are produced closer to where the receiver focuses their gaze. they also found that frequent signs are produced further from the face and closer to the resting position of arms than infrequent signs, which minimizes articulatory effort in producing frequent signs. we studied efficiency in handshapes more closely by quantifying articulatory effort in handshape configurations and perceptual effort in disambigurating between handshapes. in addition, we also explicitly compared how pressures for efficiency differ between native signs and foreign signs from asl. ## conclusion to conclude, our paper provides evidence of communicative efficiency in asl handshapes: frequently used handshapes in native asl signs require less articulatory effort. however, when examining asl signs borrowed from english, we found no correlation between articulatory/perceptual effort in these handshapes and english usage. this suggests that the foreign component of asl is not as influenced by efficiency pressures as the native component is, and optimizations for efficiency are mostly driven by asl usage. in the future, we aim to examine diachronic changes in asl handshapes to determine if the handshapes of frequently used signs become easier to articulate over time. additionally, we would like to investigate efficiency in signs borrowed from other signed languages, not just english, and to compare efficiency in the native and foreign components of signed languages other than asl that also incorporate lexical borrowing.