Deaf American Sign Language Signers Research Articles

Adjective position and referential efficiency in American Sign Language: Effects of adjective semantics, sign type and age of sign exposure

Previous research has pointed at communicative efficiency as a possible constraint on language structure. Here we investigated adjective position in American Sign Language (ASL), a language with relatively flexible word order, to test the incremental efficiency hypothesis, according to which both speakers and signers try to produce efficient referential expressions that are sensitive to the word order of their languages. The results of three experiments using a standard referential communication task confirmed that deaf ASL signers tend to produce absolute adjectives, such as color or material, in prenominal position, while scalar adjectives tend to be produced in prenominal position when expressed as lexical signs, but in postnominal position when expressed as classifiers. Age of ASL exposure also had an effect on referential choice, with early-exposed signers producing more classifiers than late-exposed signers, in some cases. Overall, our results suggest that linguistic, pragmatic and developmental factors affect referential choice in ASL, supporting the hypothesis that communicative efficiency is an important factor in shaping language structure and use.

The effects of multiple linguistic variables on picture naming in American Sign Language.

Picture-naming tasks provide critical data for theories of lexical representation and retrieval and have been performed successfully in sign languages. However, the specific influences of lexical or phonological factors and stimulus properties on sign retrieval are poorly understood. To examine lexical retrieval in American Sign Language (ASL), we conducted a timed picture-naming study using 524 pictures (272 objects and 251 actions). We also compared ASL naming with previous data for spoken English for a subset of 425 pictures. Deaf ASL signers named object pictures faster and more consistently than action pictures, as previously reported for English speakers. Lexical frequency, iconicity, better name agreement, and lower phonological complexity each facilitated naming reaction times (RT)s. RTs were also faster for pictures named with shorter signs (measured by average response duration). Target name agreement was higher for pictures with more iconic and shorter ASL names. The visual complexity of pictures slowed RTs and decreased target name agreement. RTs and target name agreement were correlated for ASL and English, but agreement was lower for ASL, possibly due to the English bias of the pictures. RTs were faster for ASL, which we attributed to a smaller lexicon. Overall, the results suggest that models of lexical retrieval developed for spoken languages can be adopted for signed languages, with the exception that iconicity should be included as a factor. The open-source picture-naming data set for ASL serves as an important, first-of-its-kind resource for researchers, educators, or clinicians for a variety of research, instructional, or assessment purposes.

Matching pictures and signs: An ERP study of the effects of iconic structural alignment in American sign language

Event-related potentials (ERPs) were used to explore the effects of iconicity and structural visual alignment between a picture-prime and a sign-target in a picture-sign matching task in American Sign Language (ASL). Half the targets were iconic signs and were presented after a) a matching visually-aligned picture (e.g., the shape and location of the hands in the sign COW align with the depiction of a cow with visible horns), b) a matching visually-nonaligned picture (e.g., the cow's horns were not clearly shown), and c) a non-matching picture (e.g., a picture of a swing instead of a cow). The other half of the targets were filler signs. Trials in the matching condition were responded to faster than those in the non-matching condition and were associated with smaller N400 amplitudes in deaf ASL signers. These effects were also observed for hearing non-signers performing the same task with spoken-English targets. Trials where the picture-prime was aligned with the sign target were responded to faster than non-aligned trials and were associated with a reduced P3 amplitude rather than a reduced N400, suggesting that picture-sign alignment facilitated the decision process, rather than lexical access. These ERP and behavioral effects of alignment were found only for the ASL signers. The results indicate that iconicity effects on sign comprehension may reflect a task-dependent strategic use of iconicity, rather than facilitation of lexical access.

The perceived mapping between form and meaning in American Sign Language depends on linguistic knowledge and task: evidence from iconicity and transparency judgments.

Iconicity is often defined as the resemblance between a form and a given meaning, while transparency is defined as the ability to infer a given meaning based on the form. This study examined the influence of knowledge of American Sign Language (ASL) on the perceived iconicity of signs and the relationship between iconicity, transparency (correctly guessed signs), 'perceived transparency' (transparency ratings of the guesses), and 'semantic potential' (the diversity (H index) of guesses). Experiment 1 compared iconicity ratings by deaf ASL signers and hearing non-signers for 991 signs from the ASL-LEX database. Signers and non-signers' ratings were highly correlated; however, the groups provided different iconicity ratings for subclasses of signs: nouns vs. verbs, handling vs. entity, and one- vs. two-handed signs. In Experiment 2, non-signers guessed the meaning of 430 signs and rated them for how transparent their guessed meaning would be for others. Only 10% of guesses were correct. Iconicity ratings correlated with transparency (correct guesses), perceived transparency ratings, and semantic potential (H index). Further, some iconic signs were perceived as non-transparent and vice versa. The study demonstrates that linguistic knowledge mediates perceived iconicity distinctly from gesture and highlights critical distinctions between iconicity, transparency (perceived and objective), and semantic potential.

Production and Comprehension of Prosodic Markers in Sign Language Imperatives.

In signed and spoken language sentences, imperative mood and the corresponding speech acts such as for instance, command, permission or advice, can be distinguished by morphosyntactic structures, but also solely by prosodic cues, which are the focus of this paper. These cues can express paralinguistic mental states or grammatical meaning, and we show that in American Sign Language (ASL), they also exhibit the function, scope, and alignment of prosodic, linguistic elements of sign languages. The production and comprehension of prosodic facial expressions and temporal patterns therefore can shed light on how cues are grammaticalized in sign languages. They can also be informative about the formal semantic and pragmatic properties of imperative types not only in ASL, but also more broadly. This paper includes three studies: one of production (Study 1) and two of comprehension (Studies 2 and 3). In Study 1, six prosodic cues are analyzed in production: temporal cues of sign and hold duration, and non-manual cues including tilts of the head, head nods, widening of the eyes, and presence of mouthings. Results of Study 1 show that neutral sentences and commands are well distinguished from each other and from other imperative speech acts via these prosodic cues alone; there is more limited differentiation among explanation, permission, and advice. The comprehension of these five speech acts is investigated in Deaf ASL signers in Study 2, and in three additional groups in Study 3: Deaf signers of German Sign Language (DGS), hearing non-signers from the United States, and hearing non-signers from Germany. Results of Studies 2 and 3 show that the ASL group performs significantly better than the other 3 groups and that all groups perform above chance for all meaning types in comprehension. Language-specific knowledge, therefore, has a significant effect on identifying imperatives based on targeted cues. Command has the most cues associated with it and is the most accurately identified imperative type across groups—indicating, we suggest, its special status as the strongest imperative in terms of addressing the speaker's goals. Our findings support the view that the cues are accessible in their content across groups, but that their language-particular combinatorial possibilities and distribution within sentences provide an advantage to ASL signers in comprehension and attest to their prosodic status.

Fingerspelled and Printed Words Are Recoded into a Speech-based Code in Short-term Memory.

We conducted three immediate serial recall experiments that manipulated type of stimulus presentation (printed or fingerspelled words) and word similarity (speech-based or manual). Matched deaf American Sign Languagesigners and hearing non-signers participated (mean reading age=14-15 years). Speech-based similarity effects were found for both stimulus types indicating that deaf signers recoded both printed and fingerspelled words into a speech-based phonological code. A manual similarity effect was not observed for printed words indicating that print was not recoded into fingerspelling (FS). A manual similarity effect was observed for fingerspelled words when similarity was based on joint angles rather than on handshape compactness. However, a follow-up experiment suggested that the manual similarity effect was due to perceptual confusion at encoding. Overall, these findings suggest that FS is strongly linked to English phonology for deaf adult signers who are relatively skilled readers. This link between fingerspelled words and English phonology allows for the use of a more efficient speech-based code for retaining fingerspelled words in short-term memory and may strengthen the representation of English vocabulary.

Words in the bilingual brain: an fNIRS brain imaging investigation of lexical processing in sign-speech bimodal bilinguals.

Early bilingual exposure, especially exposure to two languages in different modalities such as speech and sign, can profoundly affect an individual's language, culture, and cognition. Here we explore the hypothesis that bimodal dual language exposure can also affect the brain's organization for language. These changes occur across brain regions universally important for language and parietal regions especially critical for sign language (Newman et al., 2002). We investigated three groups of participants (N = 29) that completed a word repetition task in American Sign Language (ASL) during fNIRS brain imaging. Those groups were (1) hearing ASL-English bimodal bilinguals (n = 5), (2) deaf ASL signers (n = 7), and (3) English monolinguals naïve to sign language (n = 17). The key finding of the present study is that bimodal bilinguals showed reduced activation in left parietal regions relative to deaf ASL signers when asked to use only ASL. In contrast, this group of bimodal signers showed greater activation in left temporo-parietal regions relative to English monolinguals when asked to switch between their two languages (Kovelman et al., 2009). Converging evidence now suggest that bimodal bilingual experience changes the brain bases of language, including the left temporo-parietal regions known to be critical for sign language processing (Emmorey et al., 2007). The results provide insight into the resilience and constraints of neural plasticity for language and bilingualism.

Amodal Aspects of Linguistic Design

All spoken languages encode syllables and constrain their internal structure. But whether these restrictions concern the design of the language system, broadly, or speech, specifically, remains unknown. To address this question, here, we gauge the structure of signed syllables in American Sign Language (ASL). Like spoken languages, signed syllables must exhibit a single sonority/energy peak (i.e., movement). Four experiments examine whether this restriction is enforced by signers and nonsigners. We first show that Deaf ASL signers selectively apply sonority restrictions to syllables (but not morphemes) in novel ASL signs. We next examine whether this principle might further shape the representation of signed syllables by nonsigners. Absent any experience with ASL, nonsigners used movement to define syllable-like units. Moreover, the restriction on syllable structure constrained the capacity of nonsigners to learn from experience. Given brief practice that implicitly paired syllables with sonority peaks (i.e., movement)—a natural phonological constraint attested in every human language—nonsigners rapidly learned to selectively rely on movement to define syllables and they also learned to partly ignore it in the identification of morpheme-like units. Remarkably, nonsigners failed to learn an unnatural rule that defines syllables by handshape, suggesting they were unable to ignore movement in identifying syllables. These findings indicate that signed and spoken syllables are subject to a shared phonological restriction that constrains phonological learning in a new modality. These conclusions suggest the design of the phonological system is partly amodal.

Accurate and Accessible Motion-Capture Glove Calibration for Sign Language Data Collection

Motion-capture recordings of sign language are used in research on automatic recognition of sign language or generation of sign language animations, which have accessibility applications for deaf users with low levels of written-language literacy. Motion-capture gloves are used to record the wearer’s handshape. Unfortunately, they require a time-consuming and inexact calibration process each time they are worn. This article describes the design and evaluation of a new calibration protocol for motion-capture gloves, which is designed to make the process more efficient and to be accessible for participants who are deaf and use American Sign Language (ASL). The protocol was evaluated experimentally; deaf ASL signers wore the gloves, were calibrated (using the new protocol and using a calibration routine provided by the glove manufacturer), and were asked to perform sequences of ASL handshapes. Five native ASL signers rated the correctness and understandability of the collected handshape data. In an additional evaluation, ASL signers were asked to perform ASL stories while wearing the gloves and a motion-capture bodysuit (in some cases our new calibration protocol was used, in other cases, the standard protocol). Later, twelve native ASL signers watched animations produced from this motion-capture data and answered comprehension questions about the stories. In both evaluation studies, the new protocol received significantly higher scores than the standard calibration. The protocol has been made freely available online, and it includes directions for the researcher, images and videos of how participants move their hands during the process, and directions for participants (as ASL videos and English text).

396 Level of deaf child speech development based on rhythmical stimulation

American sign language (ASL) uses space itself to encode spatial information. Spatial scenes are most often described from the perspective of the person signing (the `narrator'), such that the viewer must perform what amounts to a 180° mental rotation to correctly comprehend the description. But scenes can also be described, non-canonically, from the viewer's perspective, in which case no rotation is required. Is mental rotation during sign language processing difficult for ASL signers? Are there differences between linguistic and non-linguistic mental rotation? Experiment 1 required subjects to decide whether a signed description matched a room presented on videotape. Deaf ASL signers were more accurate when viewing scenes described from the narrator's perspective (even though rotation is required) than from the viewer's perspective (no rotation required). In Experiment 2, deaf signers and hearing non-signers viewed videotapes of objects appearing briefly and sequentially on a board marked with an entrance. This board either matched an identical board in front of the subject or was rotated 180°. Subjects were asked to place objects on their board in the orientation and location shown on the video, making the appropriate rotation when required. All subjects were significantly less accurate when rotation was required, but ASL signers performed significantly better than hearing non-signers under rotation. ASL signers were also more accurate in remembering object orientation. Signers then viewed a video in which the same scenes were signed from the two perspectives (i.e. rotation required or no rotation required). In contrast to their performance with real objects, signers did not show the typical mental rotation effect. Males outperformed females on the rotation task with objects, but the superiority disappeared in the linguistic condition. We discuss the nature of the ASL mental rotation transformation, and we conclude that habitual use of ASL can enhance non-linguistic cognitive processes thus providing evidence for (a form of) the linguistic relativity hypothesis.

Mental rotation within linguistic and non-linguistic domains in users of American sign language

American sign language (ASL) uses space itself to encode spatial information. Spatial scenes are most often described from the perspective of the person signing (the `narrator'), such that the viewer must perform what amounts to a 180° mental rotation to correctly comprehend the description. But scenes can also be described, non-canonically, from the viewer's perspective, in which case no rotation is required. Is mental rotation during sign language processing difficult for ASL signers? Are there differences between linguistic and non-linguistic mental rotation? Experiment 1 required subjects to decide whether a signed description matched a room presented on videotape. Deaf ASL signers were more accurate when viewing scenes described from the narrator's perspective (even though rotation is required) than from the viewer's perspective (no rotation required). In Experiment 2, deaf signers and hearing non-signers viewed videotapes of objects appearing briefly and sequentially on a board marked with an entrance. This board either matched an identical board in front of the subject or was rotated 180°. Subjects were asked to place objects on their board in the orientation and location shown on the video, making the appropriate rotation when required. All subjects were significantly less accurate when rotation was required, but ASL signers performed significantly better than hearing non-signers under rotation. ASL signers were also more accurate in remembering object orientation. Signers then viewed a video in which the same scenes were signed from the two perspectives (i.e. rotation required or no rotation required). In contrast to their performance with real objects, signers did not show the typical mental rotation effect. Males outperformed females on the rotation task with objects, but the superiority disappeared in the linguistic condition. We discuss the nature of the ASL mental rotation transformation, and we conclude that habitual use of ASL can enhance non-linguistic cognitive processes thus providing evidence for (a form of) the linguistic relativity hypothesis.

Hemispheric specialization for ASL signs and english words: Differences between imageable and abstract forms

American Sign Language (ASL) exhibits properties for which both hemispheres in hearing people show specialized functioning (linguistic vs spatial). To determine the laterality of processing ASL in the normal intact brain, ASL signs and nonsigns were presented to each visual half field of deaf signers for lexical decision. The English glosses for these signs were presented to hearing English speakers along with nonwords. Deaf ASL signers and hearing English speakers both showed a left hemisphere advantage for abstract lexical items. ASL signers showed a significant right hemisphere advantage for imageable signs, whereas English speakers exhibited no visual field effect for imageable words. This difference in brain laterality may reflect differences in the role of imagery in the two languages.