Deaf Subjects Research Articles

DEAF VERSUS HEARING SUBJECTS' RECALL OF WORDS ON A DISTRACTION TASK AS A FUNCTION OF THE SIGN ABILITY OF THE WORDS

Subjects, including 17 deaf and 10 hearing students in Grades 11 and 12, completed a test for memory of lists of 6 words (presented visually for 10 sec.). Subjects recalled the words in writing after a distracting task of adding pairs of digits for 10 sec. Word lists are categorized as signable with a single sign, compound or combination of signs, or finger-spelling signs only. Hearing subjects recalled significantly more words in each category than did deaf subjects. Deaf subjects recalled significantly more single-signed words than either of the other two categories. Deaf subjects did not recall more compound/combination signed words than words that could only be finger-spelled. Hearing subjects also recalled significantly more single-signed words than either of the other two categories and were not superior in either of the other categories.

Adaptation of the stroop color and word test for use with deaf adults

Abstract The Stroop Color and Word Test was administered once to 20 deaf adults who responded with American Sign Language (ASL) responses, and twice to 29 hearing adults who were fluent in sign language - once using signed responses, and once using spoken responses. For the hearing subjects, signed responses were significantly slower than spoken responses in both the word and color conditions, but not in the color-word condition. No significant differences were found when comparing the rate of signing of the deaf subjects to that of the hearing subjects. These results demonstrate that Stroop responses cannot be signed as rapidly as they can be spoken; therefore, it would be inappropriate to apply standard adult norms to Stroop scores obtained from signed responses. This paper provides preliminary norms which are appropriate for use with deaf adults giving signed responses to the Stroop Color and Word Test.

Toward greater understanding of depression in deaf individuals.

We compared the prevalence of depressive symptoms among deaf and hearing college students and examined the relationships among depressive symptoms, personality characteristics, and perceived parental attitudes and behaviors in these two groups. Measures were revised to meet the language needs of the deaf subjects. Mild levels of depressive symptoms were more prevalent in the deaf than in the hearing students, but more severe depression was not. In both groups, depressive symptoms were associated with perceptions of lower maternal care and higher maternal over-protection. Deaf and hearing subjects did not differ on these perceived maternal characteristics. Depressive symptoms were associated with socially dependent personality characteristics in the hearing sample only. We discuss the implications of the findings for the role of personality development in depression in deaf individuals.

Phonological space in the speech of the hearing impaired

The vowels /a/, /i/, and /u/ form the extreme points of vowel triangle in Kannada language. First and second formant frequencies of these vowels were measured to determine the phonological space in the speech of the 30 deaf subjects and 30 normally hearing subjects. The phonological space was found to be reduced in the speech of the hearing-impaired subjects, and the reduction was primarily due to the lowering of the second formant of the vowel /i/. Therapeutic implications have been drawn.

Immediate memory in the orally trained deaf: effects of 'lipreadability' in the recall of written syllables.

Immediate recall of written lists was compared in strictly orally trained born-deaf teenagers and in hearing controls. The lists were of syllables of CV form (e.g. SHA NA ZA DA). The deaf subjects showed a significant effect of consonant 'lipreadability'. Syllable lists containing consonants like D, SH and Z whose place of articulation is not visibly distinctive and which are therefore hard to lipread are less well recalled than (phonetically and orthographically matched) syllable lists containing consonants like F, TH and B which are produced with the tongue, teeth and lips in visible configuration. We conclude that for these deaf youngsters the phonological representation of written consonants is less secure for speech sounds that are hard, rather than easy, to lipread. The oral training of these youngsters has had an effect on their internal representation of written speech. Hearing subjects showed no 'lipreadability' effect in their recall of these lists. Reading-age matched controls (aged 8-10 years) showed significantly shorter span for both list types than the deaf group. Older hearing controls (14-16 years) matched the deaf group in span and tended to recall most accurately written syllables which are not easily lipread. We discuss these comparisons and conclude that while this group of deaf subjects is using a phonological code in the recall of written syllables, it is qualitatively different from that used by hearing subjects in this task. In particular, not only hard-to-lipread consonants but also vowels may be less strongly represented in these deaf readers' 'inner voice'.

Individual differences in cognitive skills related to reading ability in the deaf.

Deaf subjects who represented a wide range of reading abilities were tested on a number of factors including reliance on phonological recoding as well as several metacognitive abilities. The sample consisted of 19 high school students who were prelingually and profoundly deaf. Subjects were given a set of paper and pencil tests that included an assessment of phonological recoding ability as well as the measures designed by Baker (1984) to assess metacognitive skills in reading. Results indicated that deaf subjects demonstrated a significant degree of reliance on phonological recoding, but that individual differences in reliance on phonological recoding showed no relationship to reading skill (r = .02). Individual differences on the metacognition measures, however, showed a strong relationship to reading ability (r = .65, p less than .01). The implications for remedial instruction for deaf students are discussed.

Multisensory narrative tracking by a profoundly deaf subject using an electrocutaneous vocoder and a vibrotactile aid.

A congenitally, profoundly deaf adult who had received 41 hours of tactual word recognition training in a previous study was assessed in tracking of connected discourse. This assessment was conducted in three phases. In the first phase, the subject used the Tacticon 1600 electrocutaneous vocoder to track a narrative in three conditions: (a) lipreading and aided hearing (L + H), (b) lipreading and tactual vocoder (L + TV), and (c) lipreading, tactual vocoder, and aided hearing (L + TV + H). Subject performance was significantly better in the L + TV + H condition than in the L + H condition, suggesting that the subject benefitted from the additional information provided by the tactual vocoder. In the second phase, the Tactaid II vibrotactile aid was used in three conditions: (a) lipreading alone, (b) lipreading and tactual aid (L + TA), and (c) lipreading, tactual aid, and aided hearing (L + TA + H). The subject was able to combine cues from the Tactaid II with those from lipreading and aided hearing. In the third phase, both tactual devices were used in six conditions: (a) lipreading alone (L), (b) lipreading and aided hearing (L + H), (c) lipreading and Tactaid II (L + TA), (d) lipreading and Tacticon 1600 (L + TV), (e) lipreading, Tactaid II, and aided hearing (L + TA + H), and (f) lipreading, Tacticon 1600, and aided hearing (L + TV + H). In this phase, only the Tactaid II significantly improved tracking performance over lipreading and aided hearing. Overall, improvement in tracking performance occurred within and across phases of this study.

Modality Effects: Do They Fall on Deaf Ears?

The present study tests the assumption of the PAS theory of echoic memory (Greene & Crowder, 1984) that the representation of acoustic features is necessary in producing modality effects. Performance by deaf subjects was compared to hearing subjects on serial and free-recall tasks with vocalizing and non-vocalizing conditions. For the serial tasks, typical modality and acoustic similarity effects were observed with hearing subjects, and no such effects were found with deaf subjects. However, for the free-recall task, modality effects were found for both deaf and hearing subjects. It is unlikely that phonological coding resulting from gestural cues mediates the modality effect, as phonological confusion errors for deaf and hearing subjects did not correlate with the size of this effect.

Language specificity in lexical organization: evidence from deaf signers' lexical organization of American Sign Language and English.

A sign decision task, in which deaf signers made a decision about the number of hands required to form a particular sign of American Sign Language (ASL), revealed significant facilitation by repetition among signs that share a base morpheme. A lexical decision task on English words revealed facilitation by repetition among words that share a base morpheme in both English and ASL, but not among those that share a base morpheme in ASL only. This outcome occurred for both deaf and hearing subjects. The results are interpreted as evidence that the morphological principles of lexical organization observed in ASL do not extend to the organization of English for skilled deaf readers.

Recognition of affective and noncanonical linguistic facial expressions in hearing and deaf subjects

This study explores the use of two types of facial expressions, linguistic and affective, in a lateralized recognition accuracy test with hearing and deaf subjects. The linguistic expressions represent unfamiliar facial expression for the hearing subjects whereas they serve as meaningful linguistic emblems for deaf signers. Hearing subjects showed left visual field advantages for both types of signals while deaf subjects' visual field asymmetries were greatly influenced by the order of presentation. The results suggest that for hearing persons, the right hemisphere may predominate in the recognition of all forms of facial expression. For deaf signers, hemispheric specialization for the processing of facial signals may be influenced by the differences these signals serve in this population. The use of noncanonical facial signals in laterality paradigms is encouraged as it provides an additional avenue of exploration into the underlying determinants of hemispheric specialization for recognition of facial expression.

The influence of final-syllable position on the vowel and word duration of deaf talkers.

Hearing talkers produce shorter vowel and word durations in multisyllabic contexts than in monosyllabic contexts. This investigation determined whether a similar effect occurs for deaf talkers, a population often characterized as lacking coarticulation in their speech. Four prelingually deafened adults and two hearing controls produced three sets of word sequences. Each set included a kernel word and six derived forms (e.g., "speed," "speedy," "speeding," etc.). The derived forms were created by adding unstressed and stressed syllables to the kernel form. A spectrographic analysis indicated that the deaf subjects did not always decrease word and vowel durations for the derivatives. Unlike hearing speakers, they often did not reduce vowel segments more than consonant segments. Three explanations are forwarded for the shortening effects. One relates to the implementation of temporal rules, the second concerns the organization imposed upon the articulators to produce speech, and the third suggests a language-independent vocal tract characteristic. The role of auditory information in developing the shortening effects is also considered.

Deafness, spelling and rhyme: how spelling supports written word and picture rhyming skills in deaf subjects.

Orally trained, congenitally deaf adolescents and hearing, reading-age-matched control subjects made rhyme judgements for pictures and for written words. Hearing children performed the task accurately. By contrast, the deaf group were very poor at rhyme judgement for words and for pictures. For hearing children, word rhyme judgement was more accurate when the words were congruent in their spelling pattern (e.g. bat/hat), less accurate when the spelling pattern of the rhyming words was incongruent ( hair/bear). Deaf subjects showed an even more pronounced effect of spelling congruence; their ability to match for rhyme when written words did not share the same spelling pattern was extremely poor. Moreover, spelling congruence predicted deaf subjects’ picture rhyming skills. We conclude that oral training for deaf people does not always permit them to achieve a reliable phonological representation of speech from lip-reading and residual hearing alone. Instead they use the written spelling of the word. This result is not predicted from some previous results that suggest that orally trained deaf people can make direct, spontaneous use of rhyme in the processing of visually presented material.

Articulatory dynamics of deaf speakers during plosive production: Aerodynamic and kinematic evidence

The production of speech requires precise movement and timing of the articulators to accurately valve the egressive airstream. While evident that deaf speakers often experience difficulty controlling such valves for speech production, the nature of such valving difficulties remains elusive. Previous aerodynamic studies have been primarily descriptive, characterizing steady-state aspects of speech production. The present study described and compared dynamic aspects of deaf and normal-hearing speakers' speech production using aerodynamic and kinematic measures. Five profoundly deaf and two normal-hearing young adults produced multiple tokens of voiced and voiceless plosive segments in varied vowel contexts, while simultaneous measures were obtained of oral and nasal airflow, oral pressure, and electroglottograph and acoustic signals. Conductance of oral and nasal vocal tract constrictions were used to describe and compare the magnitude and relative timing of articulatory gestures for deaf and hearing subjects. Computer simulation of the supraglottal air pressure and airflow waveforms was used to further investigate how these waveform variations may be related to articulatory maneuvers. Implications for speech training will be discussed. [Research supported by the Whitaker Foundation.]

Sensory integration of speech by a profoundly deaf subject using tactile aids

Previous research on tactual speech perception has focused on the relative contributions of lipreading and taction with normally hearing subjects. The integration of information from touch with that from lipreading and aided hearing by profoundly deaf subjects has not been investigated. In the present study, a profoundly deaf adult with previous tactual vocoder training [Lynch et al., J. Acoust. Soc. Am. Suppl. 1 82, S22 (1987)] was unable to identify a group of words in any one of three conditions, lipreading (L), aided hearing (H), or touch. The tactile devices used were a multichannel electrocutaneous vocoder (TV) and a two‐channel vibrotactile aid (TA). To test sensory integration, the words were randomly assigned to one of seven conditions: (a) L + H, (b) H + TV, (c) H + TA, (d) L + TV, (e) L + TA, (f) L + TV + H, and (g) L + TA + H. Results indicate that: the subject integrated information across all three modalities, yielding highest performance in the L + TV + H and L + TA + H conditions; integration occurred when both lipreading and touch were used; integration occurred when both lipreading and aided hearing were used; and each of the tactile devices provided substantial speech information. Analyses of the subject's error patterns and sentence identification performance will also be presented. [Work supported by NIDRR, Dade County Public Schools, and NIH.]

Amplitude compression and profound hearing loss.

Nine subjects with prelingually acquired, sensorineural, hearing loss were given a three-interval, forced-choice, test of speech pattern contrast perception under two amplification conditions. The first involved adjustment of the low and high frequency outputs of a two-channel Master Hearing Aid to each subject's highest comfortable level, but without compression of the short-term dynamic range of the signal. The second involved the additional compression of a 30 dB input range into the subject's dynamic range of hearing, as measured by the difference between speech awareness threshold and highest comfortable level, in each of the two channels. One of the subjects performed much better with compression than without. Among the other eight, however, there was a small but significant reduction of performance when compression was introduced. It is proposed that the one positive result is due to the increased audibility of speech cues made possible by amplitude compression. It is further proposed that the negative results are due mainly to the distortions of time-intensity cues introduced by amplitude compression. The results suggest that, in terms of potential access to meaningful speech cues, the addition of amplitude compression, to an otherwise optimized signal, is unnecessary, or even detrimental, for most profoundly deaf subjects, but could be beneficial for some.

Response Latency Measurements to Visual Cognitive Tasks by Normal Hearing and Deaf Subjects

Visual cognitive differences between hearing (N = 16) and deaf (N = 32) high-school and middle-school students were studied. Visual tasks were presented on a microcomputer and response latencies were collected. Significant differences were noted between the deaf and normal groups but not between total communication deaf and oral deaf students. These differences support the hypothesis that deaf students prefer a visual cognitive strategy. Implications for educating the deaf are discussed.

Relative Automaticity without Mastery

When writers make frequent grammatical errors, they often spend a substantial part of composing time making decisions about grammar. Studies of unskilled writers with normal hearing indicate this hyperconcern for correctness. There have been reasons to believe, however, that the attention of deaf writers who make errors is less consumed by grammatical decision making. The present study was undertaken to determine whether representative deaf writers devote as much attention to grammatical decisions as unskilled hearing subjects. Ten deaf subjects and five hearing subjects wrote and edited accounts of two short stories that were signed and spoken on videotape. Under all composing conditions, the deaf subjects' rates of pausing were substantially lower than those of the hearing writers. Combined with subjects' patterns of error correction, these findings suggest that the deaf subjects devoted substantially less attention to grammatical decision making during composition.

Automaticity in Word & Sign Recognition by Deaf Adults & Children

Three experiments employed the Stroop task to investigate the automaticity of recognizing signs and printed words by prelingually deaf subjects Experiments 1 and 2 involved words for color and signs for color Experiment 3 Involved numerals, printed words for number, and signs for number. In all cases, Incongruent but irrelevant signed and printed stimuli led to Interference in reporting the color or number of stimulus elements, and thus indicated automatic semantic access to the meanings of words and of signs by subjects as early as age eleven. Surprisingly, however, printed words consistently created significantly more interference than did signs. Possible explanations and Implications of these findings are discussed.

A single-transducer vibrotactile aid to lipreading

A vibrotactile aid to lipreading which presents information about voicing as well as a cue to the presence of high frequency consonants was evaluated on four deaf subjects. A test of consonant perception presented with lipreading alone, and with lipreading supplemented by the aid, showed improvements in the perception of voicing and manner of articulation in the aided condition. Testing at the word and sentence level showed differing results for the subjects completing the tasks. A congenitally deaf subject with a history of non-hearing-aid use showed no improvements in the aided conditions whereas another subject with a history of very successful hearing aid used evidenced improvements in the aided condition for both sets of materials. Testing at the level of connected discourse revealed improvements in the aided condition for two subjects but not for a subject with limited hearing aid experience. The significance of the results and future research directions are discussed.

Limits of visual communication: the effect of signal-to-noise ratio on the intelligibility of American Sign Language.

To determine the limits of human observers' ability to identify visually presented American Sign Language (ASL), the contrast s and the amount of additive noise n in dynamic ASL images were varied independently. Contrast was tested over a 4:1 range; the rms signal-to-noise ratios (s/n) investigated were s/n = 1/4, 1/2, 1, and infinity (which is used to designate the original, uncontaminated images). Fourteen deaf subjects were tested with an intelligibility test composed of 85 isolated ASL signs, each 2-3 sec in length. For these ASL signs (64 x 96 pixels, 30 frames/sec), subjects' performance asymptotes between s/n = 0.5 and 1.0; further increases in s/n do not improve intelligibility. Intelligibility was found to depend only on s/n and not on contrast. A formulation in terms of logistic functions was proposed to derive intelligibility of ASL signs from s/n, sign familiarity, and sign difficulty. Familiarity (ignorance) is represented by additive signal-correlated noise; it represents the likelihood of a subject's knowing a particular ASL sign, and it adds to s/n. Difficulty is represented by a multiplicative difficulty coefficient; it represents the perceptual vulnerability of an ASL sign to noise and it adds to log(s/n).