Effects of rate of presentation on the reception of American Sign Language.

Previous research on the visual reception of fingerspelled English suggests that communication rates are limited primarily by constraints on production. Studies of artificially accelerated fingerspelling indicate that reception of fingerspelled sentences is highly accurate for rates up to 2 to 3 times those that can be produced naturally. The current paper reports on the results of a comparable study of the reception of American Sign Language (ASL). Fourteen native deaf ASL signers participated in an experiment in which videotaped productions of isolated ASL signs or ASL sentences were presented at normal playback speed and at speeds of 2, 3, 4, and 6 times normal speed. For isolated signs, identification scores decreased from 95% correct to 46% correct across the range of rates that were tested; for sentences, the ability to identify key signs decreased from 88% to 19% over the range of rates tested. The results indicate a breakdown in processing at around 2.5-3 times the normal rate as evidenced both by a substantial drop in intelligibility in this region and by a shift in error patterns away from semantic and toward formational. These results parallel those obtained in previous studies of the intelligibility of the auditory reception of time-compressed speech and the visual reception of accelerated fingerspelling. Taken together, these results suggest a modality-independent upper limit to language processing.

A study of the tactual reception of sign language.

One of the natural methods of tactual communication in common use among individuals who are both deaf and blind is the tactual reception of sign language. In this method, the receiver (who is deaf-blind) places a hand (or hands) on the dominant (or both) hand(s) of the signer in order to receive, through the tactual sense, the various formational properties associated with signs. In the study reported here, 10 experienced deaf-blind users of either American Sign Language (ASL) or Pidgin Sign English (PSE) participated in experiments to determine their ability to receive signed materials including isolated signs and sentences. A set of 122 isolated signs was received with an average accuracy of 87% correct. The most frequent type of error made in identifying isolated signs was related to misperception of individual phonological components of signs. For presentation of signed sentences (translations of the English CID sentences into ASL or PSE), the performance of individual subjects ranged from 60-85% correct reception of key signs. Performance on sentences was relatively independent of rate of presentation in signs/sec, which covered a range of roughly 1 to 3 signs/sec. Sentence errors were accounted for primarily by deletions and phonological and semantic/syntactic substitutions. Experimental results are discussed in terms of differences in performance for isolated signs and sentences, differences in error patterns for the ASL and PSE groups, and communication rates relative to visual reception of sign language and other natural methods of tactual communication.

Using immediate recall to assess language proficiency in deaf students.

We used an immediate recall paradigm to study the effects of list organization and semantic and grammatical features of printed stimuli on working memory capacity in deaf students with differing English language abilities. Thirty lists of five organizational types (random words, semantically related words, semantically paired words, scrambled sentences, and grammatical sentences) were presented to two groups of deaf students who differed in their proficiency in the English language. The students were required to recall the lists in writing. The results indicate that, overall, the students with higher levels of English language proficiency recalled significantly more than those with lower levels. Additionally, semantic and syntactic organization of the lists had different effects on the two groups of students. Semantic pairing aided the low-level group significantly more than the high-level group, whereas the syntactic organization of the grammatical sentences aided the high-level group significantly more. Implications for assessing language ability in deaf students are discussed.

Pragmatic and linguistic constraints on message formulation: a cross-linguistic study of English and ASL.

This study provides a cross-linguistic replication, using American Sign Language (ASL), of the Brown and Dell (1987) finding that when relaying an action involving an instrument, English speakers are more likely to explicitly mention the instrument if it is atypically, rather than typically, used to accomplish that action. Subjects were 20 hearing-impaired users of English and 20 hearing-impaired users of ASL. Each subject read and retold, in either English or ASL, 20 short stories. Analyses of the stories revealed production decision differences between ASL and English, but no differences related to hearing status. In ASL, there is more explicitness, and importance seems to play a more pivotal role in instrument specification. The results are related to differences in the typology of English and ASL and are discussed with regard to second-language learning and translation.

A study of the tactual and visual reception of fingerspelling.

A method of communication in frequent use among members of the deaf-blind community is the tactual reception of fingerspelling. In this method, the hand of the deaf-blind individual is placed on the hand of the sender to monitor the handshapes and movements associated with the letters of the manual alphabet. The purpose of the current study was to examine the ability of experienced deaf-blind subjects to receive fingerspelled materials, including sentences and connected text, through the tactual sense. A parallel study of the reception of fingerspelling through the visual sense was also conducted using sighted deaf subjects. For both visual and tactual reception of fingerspelled sentences, accuracy of reception was examined as a function of rate of presentation. In the tactual study, where rates were limited to those that could be produced naturally by an experienced interpreter, highly accurate reception of conversational sentence materials was observed throughout the range of naturally produced rates (i.e., 2 to 6 letters/s). In the visual study, rates in excess of those that can be produced naturally were achieved through variable-speed playback of videotapes of fingerspelled sentences. The results of this study indicate that performance varies systematically as a function of rate of presentation, with scores of 50% correct on conversational sentences obtained at rates of 12 to 16 letters/s (i.e., rates roughly double to triple normal speed). These results suggest that normal communication rates for the visual reception of fingerspelling are restricted by limitations on the rate of manual production. Although maximal rates of natural manual production of fingerspelling correspond to the presentation of a new handshape on the order of once every 150-20 ms, the data from the sped-up visual study suggest that experienced receivers of visual fingerspelling are able to receive sentences at substantially higher rates of fingerspelling (which are, in fact, comparable to communication rates for spoken English).

Looking through phonological shape to lexical meaning: the bottleneck of non-native sign language processing.

In two studies, we find that native and non-native acquisition show different effects on sign language processing. Subjects were all born deaf and used sign language for interpersonal communication, but first acquired it at ages ranging from birth to 18. In the first study, deaf signers shadowed (simultaneously watched and reproduced) sign language narratives given in two dialects, American Sign Language (ASL) and Pidgin Sign English (PSE), in both good and poor viewing conditions. In the second study, deaf signers recalled and shadowed grammatical and ungrammatical ASL sentences. In comparison with non-native signers, natives were more accurate, comprehended better, and made different kinds of lexical changes; natives primarily changed signs in relation to sign meaning independent of the phonological characteristics of the stimulus. In contrast, non-native signers primarily changed signs in relation to the phonological characteristics of the stimulus independent of lexical and sentential meaning. Semantic lexical changes were positively correlated to processing accuracy and comprehension, whereas phonological lexical changes were negatively correlated. The effects of non-native acquisition were similar across variations in the sign dialect, viewing condition, and processing task. The results suggest that native signers process lexical structural automatically, such that they can attend to and remember lexical and sentential meaning. In contrast, non-native signers appear to allocate more attention to the task of identifying phonological shape such that they have less attention available for retrieval and memory of lexical meaning.