Visual field asymmetries for motion processing in deaf and hearing signers

Recently, we reported a strong right visual field/left hemisphere advantage for motion processing in deaf signers and a slight reverse asymmetry in hearing nonsigners (Bosworth & Dobkins, 1999). This visual field asymmetry in deaf signers may be due to auditory deprivation or to experience with a visual-manual language, American Sign Language (ASL). In order to separate these two possible sources, in this study we added a third group, hearing native signers, who have normal hearing and have learned ASL from their deaf parents. As in our previous study, subjects performed a direction-of-motion discrimination task at different locations across the visual field. In addition to investigating differences in left vs right visual field asymmetries across subject groups, we also asked whether performance differences exist for superior vs inferior visual fields and peripheral vs central visual fields. Replicating our previous study, a robust right visual field advantage was observed in deaf signers, but not in hearing nonsigners. Like deaf signers, hearing signers also exhibited a strong right visual field advantage, suggesting that this effect is related to experience with sign language. These results suggest that perceptual processes required for the acquisition and comprehension of language (motion processing in the case of ASL) are recruited by the left, language-dominant, hemisphere. Deaf subjects also exhibited an inferior visual field advantage that was significantly larger than that observed in either hearing group. In addition, there was a trend for deaf subjects to perform relatively better on peripheral than on central stimuli, while both hearing groups showed the reverse pattern. Because deaf signers differed from hearing signers and nonsigners along these domains, the inferior and peripheral visual field advantages observed in deaf subjects is presumably related to auditory deprivation. Finally, these visual field asymmetries were not modulated by attention for any subject group, suggesting they are a result of sensory, and not attentional, factors.     

Deterioration of the phonological processing skills in adults with an acquired severe hearing loss

Phonological processing was examined in a group of individuals with an acquired severe hearing loss and compared to a group of matched normal hearing individuals. The hearing-impaired group was significantly slower and less accurate when performing a visual rhyme-judgement task, and produced fewer rhyming word pairs on a rhyme-generation task than the normal hearing group. In contrast, the hearing-impaired group performed on a par with the normal hearing group on verbal working memory tasks. It is concluded that specific aspects of the phonological system deteriorate in this population as a function of auditory deprivation. In particular, the phonological representations are impaired and this impairment also affects the ability to rapidly perform phonological operations (i.e., analyse and compare). In contrast, phonological processing involved in verbal working memory is preserved in this population.     

The influence of two years of school music training in secondary school on visual and auditory memory

The present study tested the effect of an extended music curriculum (EMC) for two years in secondary school, consisting of musical instrument, auditory perception, and music theory training, on children's visual and auditory memory. We tested 10-year-old children who had just started EMC and children without EMC (T0) in visual and auditory memory and retested the same children two years later (T1) to observe the effects of school music training. Confounding variables, like intelligence, socioeconomic status, extracurricular schooling, motivation to avoid work, and musical aptitude were controlled. Prior to the beginning of the music training no differences in the control variables and the memory variables between children with and without EMC were revealed. Children with EMC improved significantly from T0 to T1 in visual as well as in auditory memory. Such an improvement was not found for children without EMC. We conclude that extended school music training enhances children's visual and auditory memory.     

Implicit sequence learning in deaf children with cochlear implants

Deaf children with cochlear implants (CIs) represent an intriguing opportunity to study neurocognitive plasticity and reorganization when sound is introduced following a period of auditory deprivation early in development. Although it is common to consider deafness as affecting hearing alone, it may be the case that auditory deprivation leads to more global changes in neurocognitive function. In this paper, we investigate implicit sequence learning abilities in deaf children with CIs using a novel task that measured learning through improvement to immediate serial recall for statistically consistent visual sequences. The results demonstrated two key findings. First, the deaf children with CIs showed disturbances in their visual sequence learning abilities relative to the typically developing normal-hearing children. Second, sequence learning was significantly correlated with a standardized measure of language outcome in the CI children. These findings suggest that a period of auditory deprivation has secondary effects related to general sequencing deficits, and that disturbances in sequence learning may at least partially explain why some deaf children still struggle with language following cochlear implantation.     

Executive abilities in children with congenital visual impairment in mid-childhood

The role of vision and vision deprivation in the development of executive function (EF) abilities in childhood is little understood; aspects of EF such as initiative, attention orienting, inhibition, planning and performance monitoring are often measured through visual tasks. Studying the development and integrity of EF abilities in children with congenital visual impairment (VI) may provide important insights into the development of EF and also its possible relationship with vision and non-visual senses. The current study investigates non-visual EF abilities in 18 school-age children of average verbal intelligence with VI of differing levels of severity arising from congenital disorders affecting the eye, retina, or anterior optic nerve. Standard auditory neuropsychological assessments of sustained and divided attention, phonemic, semantic and switching verbal fluency, verbal working memory, and ratings of everyday executive abilities by parents were undertaken. Executive skills were compared to age-matched typically-sighted (TS) typically-developing children and across levels of vision (mild to moderate VI [MVI] or severe to profound VI [SPVI]). The results do not indicate significant differences or deficits on direct assessments of verbal and auditory EF between the groups. However, parent ratings suggest difficulties with everyday executive abilities, with the greatest difficulties in those with SPVI. The findings are discussed as possibly reflecting increased demands of behavioral executive skills for children with VI in everyday situations despite auditory and verbal EF abilities in the typical range for their age. These findings have potential implications for clinical and educational practices.     

Sensitivity of persons with hearing impairment to visual emotional expression — compensation or deficit?

The research examined whether subjects with hearing impairment would differ from normal hearing subjects in their ability to decode emotions from video stimuli (48 video takes in which two actors portrayed six different emotions). Studies in tactile and visual perception lead one to expect deficits, while there is also some evidence for compensation. Twenty-six subjects with hearing impairment and 26 matched normal hearing subjects participated (average age = 25.5 years; nine female, 17 male subjects in each group). Results indicate that in general subjects with hearing impairment were slightly less successful in decoding emotions from the visual stimuli than the normal hearing subjects. A comparison between highly (loss > 60–90 dBA) and moderately (loss about 30–60 dBA) impaired subjects on the other hand indicated poorer emotion decoding only for the moderately impaired group. Post-hoc analyses indicated that these effects were specific to males. Results are discussed with respect to compensation versus deficit, and with respect to issues of training.     

Using a multi‐feature paradigm to measure mismatch responses to minimal sound contrasts in children with cochlear implants and hearing aids

Our aim was to explore whether a multi‐feature paradigm (Optimum‐1) for eliciting mismatch negativity (MMN) would objectively capture difficulties in perceiving small sound contrasts in children with hearing impairment (HI) listening through their hearing aids (HAs) and/or cochlear implants (CIs). Children aged 5–7 years with HAs, CIs and children with normal hearing (NH) were tested in a free‐field setting using a multi‐feature paradigm with deviations in pitch, intensity, gap, duration, and location. There were significant mismatch responses across all subjects that were positive (p‐MMR) for the gap and pitch deviants (F(1,43) = 5.17, p = 0.028 and F(1,43) = 6.56, p = 0.014, respectively) and negative (MMN) for the duration deviant (F(1,43) = 4.74, p = 0.035). Only the intensity deviant showed a significant group interaction with MMN in the HA group and p‐MMR in the CI group (F(2,43) = 3.40, p = 0.043). The p‐MMR correlated negatively with age, with the strongest correlation in the NH subjects. In the CI group, the late discriminative negativity (LDN) was replaced by a late positivity with a significant group interaction for the location deviant. Children with severe HI can be assessed through their hearing device with a fast multi‐feature paradigm. For further studies a multi‐feature paradigm including more complex speech sounds may better capture variation in auditory processing in these children.     

Temporal processing in deaf signers

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.     

Working memory deficits in boys with attention deficit/hyperactivity disorder (ADHD): An examination of orthographic coding and episodic buffer processes

The episodic buffer component of working memory was examined in children with attention deficit/hyperactivity disorder (ADHD) and typically developing peers (TD). Thirty-two children (ADHD = 16, TD = 16) completed three versions of a phonological working memory task that varied with regard to stimulus presentation modality (auditory, visual, or dual auditory and visual), as well as a visuospatial task. Children with ADHD experienced the largest magnitude working memory deficits when phonological stimuli were presented via a unimodal, auditory format. Their performance improved during visual and dual modality conditions but remained significantly below the performance of children in the TD group. In contrast, the TD group did not exhibit performance differences between the auditory- and visual-phonological conditions but recalled significantly more stimuli during the dual-phonological condition. Furthermore, relative to TD children, children with ADHD recalled disproportionately fewer phonological stimuli as set sizes increased, regardless of presentation modality. Finally, an examination of working memory components indicated that the largest magnitude between-group difference was associated with the central executive. Collectively, these findings suggest that ADHD-related working memory deficits reflect a combination of impaired central executive and phonological storage/rehearsal processes, as well as an impaired ability to benefit from bound multimodal information processed by the episodic buffer.     

Multi-limb coordination and rhythmic variability under varying sensory availability conditions in children with DCD

Children with Developmental Coordination Disorder (DCD) have sensory processing deficits; how do these influence the interface between sensory input and motor performance? Previously, we found that children with DCD were less able to organize and maintain a gross motor coordination task in time to an auditory cue, particularly at higher frequencies [Whitall, J., Getchell, N., McMenamin, S., Horn, C., Wilms-Floet, A., & Clark, J. (2006). Perception-action coupling in children with and without DCD: Frequency locking between task relevant auditory signals and motor responses in a dual motor task. Child: Care, Health, and Development, 32, 679-692]. In the present study, we examine the same task (clapping in-phase to marching on a platform) under conditions involving the removal of vision and hearing. Eleven children with DCD (mean=7.21, SD=0.52 years), 7 typically developing (TD) children (mean=6.95+/-0.72 years), and 10 adults performed continuous clapping while marching under four conditions: with vision and hearing, without vision, without hearing, and without both. Results showed no significant condition effects for any measure taken. The DCD group was more variable in phasing their claps and footfalls than both the adult group and the TD group. There were also significant group effects for inter-clap interval coefficient of variation and inter-footfall interval coefficient of variation, with the DCD group being the most variable for both measures. Coherence analysis between limb combinations (e.g., left arm-right arm, right arm-left leg) revealed that the adults exhibited significantly greater coherence for each combination than both of the children's groups. The TD group showed significantly greater coherence than the DCD group for every limb combination except foot-foot and left hand-right foot. Measures of approximate entropy indicated that adults differed from children both with and without DCD in the structure of the variability across a trial with adults showing more complexity. Children with DCD are able to accomplish a self-initiated gross-motor coordination task but with increased variability for most but not all measures compared to typically developing children. The availability of visual and/or auditory information does not play a significant role in stabilizing temporal coordination of this task, suggesting that these are not salient sources of information for this particular task.     

Generating inferences from written and spoken language: A comparison of children with visual impairment and children with sight

The two experiments reported here investigated the ability of sighted children and children with visual impairment to comprehend text and, in particular, to draw inferences both while reading and while listening. Children were assigned into ‘comprehension skill’ groups, depending on the degree to which their reading comprehension skill was in line with that predicted by their decoding skill. They then read (either print or Braille) and listened to a series of novel short stories. These were followed by a series of questions, which required either the generation of inferences, or an answer that could be taken literally from the text. The results suggest that children with and without sight are comparable in their ability to draw inferences, and that children with visual impairment show an advantage for literal questions under auditory presentation.     

Auditory backward-masking performance by children who stutter and its relation to dysfluency rate

The fluency of people who stutter is affected markedly when auditory feedback is altered, suggesting that stuttering may be associated with hearing. Peripheral hearing problems, however, are no more common in people who stutter than in those who do not. Performance was investigated in a task that involves central auditory processing (backward masking). Children who stuttered had deficits in backward masking (indicated by higher thresholds) compared with a group of fluent control children. The backward-masking thresholds were positively correlated with frequency of stuttering.     

Latency of head movements of normal hearing and auditorially handicapped children

19 auditory handicapped and 19 hearing children (4- to 12-yr.-old) were compared for performance on a visual localization task during which visual stimuli were presented both within and beyond the initial field of view. In the latter situations the localization response depends, initially on a cognitive map of the surrounding environment. The youngest group (4- and 5-yr.-old) of auditorially handicapped children showed, relative to their nondeaf peers, slower latencies of head movements to stimuli beyond their initial field of view. This finding is interpreted as these subjects having at their disposal a less precise, less adequate, cognitive map of the environment, possibly arising from a disturbed crossmodal integration as a consequence of the absence of auditory input.     

The effectiveness of imagery and sentence strategy instructions as a function of visual and auditory processing in young school-age children

The relationship between auditory and visual processing modality and strategy instructions was examined in first- and second-grade children. A Pictograph Sentence Memory Test was used to determine dominant processing modality as well as to assess instructional effects. The pictograph task was given first followed by auditory or visual interference. Children who were disrupted more by visual interference were classed as visual processors and those more disrupted by auditory interference were classed as auditory processors. Auditory and visual processors were then assigned to one of three conditions: interactive imagery strategy, sentence strategy, or a control group. Children in the imagery and sentence strategy groups were briefly taught to integrate the pictographs in order to remember them better. The sentence strategy was found to be effective for both auditory and visual processors, whereas the interactive imagery strategy was effective only for auditory processors.     

Mechanisms that underlie coordination in children with developmental coordination disorder

The authors examined potential mechanisms underlying motor coordination in children with developmental coordination disorder (DCD). Because children with DCD experience difficulty processing visual, auditory, and vibrotactile information, the authors explored patterns of choice reaction time (RT) in young (6-7 years) and older (9-10 years) children with and without DCD by using a compatibility-incompatibility paradigm and different sensory modalities. Young children responded more slowly than older children to visual, auditory, and vibrotactile stimuli. Children with DCD took longer than typical children to process visual and vibrotactile stimuli under more complex stimulus-response mappings. Young children with DCD responded more slowly than typical children to visual and vibrotactile information under incompatible conditions. Children with DCD responded faster than unaffected children to auditory stimuli. The results suggest that there is a developmental nature in the processing of visual and auditory input and imply that the vibrotactile sensory modality may be key to the motor coordination difficulties of children with DCD.     

Tactile spatial ability: Lateralized performance of deaf and hearing age groups

Hearing adults, 8- and 6-year-old children, together with deaf 9-year-old children, were tested on a unimodal haptic matching task. One additional group of adults was tested with a shorter stimulus presentation time. Data indicated that left-hand superiority was most evident in the performances of the older hearing children, and of the adults with the shorter presentation time. Hemispheric specialization was less noticeable for the younger hearing group, but the task may have been too difficult. A slight right-hand superiority was found in the performance of adults with long presentation time. This may reflect the simplicity of the task for these subjects. Deaf children did not show any clear hand differences, but were superior in overall performance to hearing children.     

Looking where you listen: visual cues and auditory attention

In the non-laboratory environment, we are generally able to see the source of the sounds to which we are attending. In a preliminary examination of how and to what degree we might use this visual information, subjects shadowed one of two female voices when able to see the persons speaking (Experiment I) or when able to see, and thus precisely localize, the auditory loudspeakers (Experiment II). Selective performance was improved by being able to see the lip movements of the people whose voices were heard, and by being able to localize visually the sources of the voices.     

Phonological coding in word reading: Evidence from hearing and deaf readers

The ability of prelingually, profoundly deaf readers to access phonological information during reading was investigated in three experiments. The experiments employed a task, developed by Meyer, Schvaneveldt, and Ruddy (1974), in which lexical decision response times (RTs) to orthographically similar rhyming (e.g., WAVE-SAVE) and nortrhyming (e.g., HAVE-CAVE) word pairs were compared with RTs to orthographically and phonologically dissimilar control word pairs. The subjects of the study were deaf college students and hearing college students. In Experiments 1 and 2, in which the nonwords were pronounceable, the deaf subjects, like the hearing subjects, were facilitated in their RTs to rhyming pairs, but not to nonrhyming pairs. In Experiment 3, in which the nonwords were unpronounceable, both deaf and hearing subjects were facilitated in their RTs to both rhyming and nonrhyming pairs, with the facilitation being significantly greater for the rhyming pairs. These results indicate that access to phonological information is possible despite prelingual and profound hearing impairment. As such, they run counter to claims that deaf individuals are limited to the use of visual strategies in reading. Given the impoverished auditory, experience of such readers, these results suggest that the use of phonological information need not be tied to the auditory modality.