"More" is "less": sign language comprehension in deaf and hearing children.
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Autistic children have severe problems in acquiring language. For this reason, special techniques have been developed to teach them speech and sign language. It is not known, however, whether these children will profit more from speech or sign training. The research literature implies that verbal imitative ability may predict language learning characteristics particularly in the speech modality. In view of this possibility, two groups of autistic children--good versus poor verbal imitators--were studied within the context of a receptive label acquisition task. Good imitators acquired receptive speech whereas poor imitators typically did not. Both groups acquired receptive signs. The results were discussed in terms of the role that imitative ability may play with respect to language acquisition in this population.
The development of linguistic and cognitive flexibility was examined by evaluating nonliteral language use by 20 deaf and 20 hearing children aged 7;11 to 15;0 years. Each subject was videotaped telling stories on two experimenter-supplied themes. Deaf subjects' stories were translated and transcripts for both samples were scored for gesture, pantomime, linguistic modifications, and inventions as well as novel and frozen trope. Results indicated deaf children produced just as much figurative language in sign language as their matched hearing age-mates did in English. Deaf subjects exceeded their hearing peers in other types of creative productions. They also evidenced a "literal period" in language development, comparable to hearing children but delayed approximately 4 years. Findings are discussed in terms of their implications for understanding both language and cognitive flexibilities of deaf children.
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Congenitally deaf subjects exposed to tachistoscopic presentation of English words, British Sign Language (BSL) signs, manual letters stimuli and a non-verbal task showed a left hemisphere advantage for English words and signs, a right hemisphere advantage for manual letters and no field differences for the non-verbal task.
Virtually all right-handed individuals are left hemisphere dominant for language. Sign languages of the deaf provide an unusual vehicle for exploring the link between handedness and hemispheric specialization for language since in sign language the hands themselves are the language articulators. Performance of the right and left hand was examined in deaf native users of American Sign Language (ASL) for speeded production of one-handed signs and for shadowing of signed discourse. Opposite patterns of asymmetries in hand performance were found in right- and left-handers. However, left-handers were more flexible than right-handers in signing with their non-preferred hand. Furthermore, unusual patterns of hand use for sign were found in a deaf signer with a left hemisphere lesion, possibly indexing increased mediation of the intact hemisphere. Implications for brain organization of language in a visual-gestural mode are discussed.
Reaching towards a visual object in the absence of visual referents relies on a chain of information, from the sensory signals encoding the object's image on the retina, to the motor signals driving the hand. One link in this chain is an extraretinal eye position signal (EEPS), which specifies the position of the eye in the head. EEPS must be updated in precise coordination with the eye's rapidly changing position, or perisaccadic visual targets will be mislocalized. There have been conflicting reports about the existence and nature of mislocalizations associated with saccades. We measured perisaccadic visual localization by presenting brief (250 microseconds), bright (6000 cd/m2), binocular, gaze-point (foveal) probe flashes in an otherwise dark field to normal human subjects instructed to point to them with an unseen hand. Saccade and fixation targets were auditory, making intravisual comparison impossible. Saccades, elicited randomly to left and right of straight ahead, had a mean magnitude of 8.9 deg. Control trials, employing only non-perisaccadic probes and providing feedback of pointing errors, were randomly interspersed, to monitor and control drift of hand-eye coordination. On average, localization began to shift for probes presented 2 msec after the eye began to move, reaching a stable post-saccadic value with time constant tau = 71 msec. A second experiment was similar, except that viewing was monocular, and probes were presented randomly, at gaze (on fovea), 6 deg left of gaze (right of fovea) and 6 deg right of gaze (left of fovea). The main analysis treated saccades larger than 8 deg: their mean magnitude was 12.9 deg. Flashes left of gaze were relocalized faster (tau = 65 msec) than flashes right of gaze (tau = 129 msec) around the time of leftward saccades. In contrast, flashes right of gaze were relocalized faster (tau = 62 msec) than flashes left of gaze (tau = 90 msec) around the time of rightward saccades. Time constant was independent of saccade size. Updating began for probes presented within 4 msec of the beginning of saccades, and was not a function of saccade or flash direction. Thus, there were no systematic mislocalizations of probes presented before eye movement, and large mislocalizations of probes presented during and after. Mislocalizations were, on average, always in the direction opposite the saccade, and were maximal (about half the magnitude of the completed saccade) near the end of the saccade. Stable post-saccadic localization was not achieved until about 100-300 msec after completion of a saccade; EEPS was updated slowly, compared to eye position itself. The visual field was not remapped uniformly: the side that would normally contain the target of a visually evoked saccade (and usually the target of a corrective saccade), was updated with a shorter time constant.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A normally hearing left-handed patient familiar with American Sign Language (ASL) was assessed under sodium amytal conditions and with left cortical stimulation in both oral speech and signed English. Lateralization was mixed but complementary in each language mode: the right hemisphere perfusion severely disrupted motoric aspects of both types of language expression, the left hemisphere perfusion specifically disrupted features of grammatical and semantic usage in each mode of expression. Both semantic and syntactic aspects of oral and signed responses were altered during left posterior temporal-parietal stimulation. Findings are discussed in terms of the neurological organization of ASL and linguistic organization in cases of early left hemisphere damage.
The imitation and recognition ability of brain-damaged and normal subjects was tested for 30 pairs of semantically matched ASL signs and corresponding Amer-Ind gestures. Subjects were rated according to severity and site of lesion. They were 6 nonaphasic, right-hemisphere brain-damaged subjects, 12 aphasic subjects, and 12 non-brain-damaged geriatric subjects. Results indicated that the Amer-Ind gestures were significantly easier to imitate and to recognize than the matched ALS signs. The relationships between these gestural abilities and severity of aphasia, site of lesion, Amer-Ind transparency ratings, and subjects' performance on a standardized aphasia test are outlined. The theoretical implications that concern the neural systems which mediate spoken and limb gestures are discussed.
The auditory and visual modalities differ in their capacities for temporal analysis, and speech relies on more rapid temporal contrasts than does sign language. We examined whether congenitally deaf signers show enhanced or diminished capacities for processing rapidly varying visual signals in light of the differences in sensory and language experience of deaf and hearing individuals. Four experiments compared rapid temporal analysis in deaf signers and hearing subjects at three different levels: sensation, perception, and memory. Experiment 1 measured critical flicker frequency thresholds and Experiment 2, two-point thresholds to a flashing light. Experiments 3-4 investigated perception and memory for the temporal order of rapidly varying nonlinguistic visual forms. In contrast to certain previous studies, specifically those investigating the effects of short-term sensory deprivation, no significant differences between deaf and hearing subjects were found at any level. Deaf signers do not show diminished capacities for rapid temporal analysis, in comparison to hearing individuals. The data also suggest that the deficits in rapid temporal analysis reported previously for children with developmental language delay cannot be attributed to lack of experience with speech processing and production.