Temporal processing ability in above average and average readers

Improved reading measures in adults with dyslexia following transcranial direct current stimulation treatment

To better understand the contribution of the dorsal system to word reading, we explored transcranial direct current stimulation (tDCS) effects when adults with developmental dyslexia received active stimulation over the visual extrastriate area MT/V5, which is dominated by magnocellular input. Stimulation was administered in 5 sessions spread over two weeks, and reading speed and accuracy as well as reading fluency were assessed before, immediately after, and a week after the end of the treatment. A control group of adults with developmental dyslexia matched for age, gender, reading level, vocabulary and block-design WAIS-III sub-tests and reading level was exposed to the same protocol but with sham stimulation. The results revealed that active, but not sham stimulation, significantly improved reading speed and fluency. This finding suggests that the dorsal stream may play a role in efficient retrieval from the orthographic input lexicon in the lexical route. It also underscores the potential of tDCS as an intervention tool for improving reading speed, at least in adults with developmental dyslexia.

Contribution of temporal processing skills to reading comprehension in 8-year-olds: evidence for a mediation effect of phonological awareness

This study tested whether the association between temporal processing (TP) and reading is mediated by phonological awareness (PA) in a normative sample of 615 eight-year-olds. TP was measured with auditory and bimodal (visual-auditory) temporal order judgment tasks and PA with a phoneme deletion task. PA partially mediated the association between both auditory and bimodal TP and reading, above nonverbal abilities, vocabulary, and processing speed. PA explained a larger proportion of the association between auditory TP and reading (56% vs. 39% for bimodal TP), and most of the association between bimodal TP and reading was direct. This finding is consistent with a dual-phonological and visual-pathway model of the association between TP and reading in normative reading skills.

Teste GIN: detecção de gap em crianças com desvio fonológico

OBJETIVO: investigar a resolução temporal: detecção de gaps em crianças com desvios fonológicos por meio do teste GIN e relacionar o grau do desvio fonológico com desempenho no teste GIN. MÉTODO: 6 indivíduos, de ambos os gêneros, 5 meninos e 1 menina, com idade entre 10 e 11 anos, com diagnóstico de desvio fonológico, em atendimento na clínica-escola do curso de Fonoaudiologia da FEAD de Belo Horizonte/MG, todos com ausência de perda auditiva e problemas neurológicos e/ou cognitivos. Os participantes foram submetidos ao Teste GIN, em intensidade de 50dB acima do limiar. RESULTADOS: das 06 crianças avaliadas, 5 (83,33%) encontram-se alteradas e apenas 1 (16,67%) obteve valores dentro do padrão de normalidade. Apesar da pequena amostra, viu-se que 83,33% das crianças com desvio fonológico tiveram limiares do GIN aquém do esperado para faixa etária. Porém não foi possível estabelecer uma relação direta entre grau de classificação do desvio fonológico e o baixo desempenho obtido no teste GIN, no qual apenas 1 criança com desvio médio moderado apresentou pior desempenho no teste GIN. CONCLUSÃO: crianças com desvio fonológico podem apresentar alteração no processamento temporal.

Dorsal stream modulation of visual word recognition in skilled readers

We examined the hypothesis of a visual magnocellular involvement in intact reading, by testing a group of skilled readers in lateralized versions of coherent motion detection and lexical decision tasks. Motion detection thresholds were used to divide subjects into groups of poor and good motion detectors, their performance in lexical judgment of four letter string types was then compared. Although all subjects were skilled readers, good motion detectors were significantly faster than poor motion detectors when responding to words presented to the right visual field. We propose a role for the dorsal stream in facilitation of word recognition in LH language areas.

Auditory and visual stream segregation in children and adults: an assessment of the amodality assumption of the 'sluggish attentional shifting' theory of dyslexia

Among the hypotheses relating dyslexia to a temporal processing disorder, Hari and Renvall (Hari, R., Renvall, H., 2001. Impaired processing of rapid stimulus sequences in dyslexia. Trends. Cognit. Sci. 5, 525-532.) argued that dyslexic individuals would show difficulties at an attentional level, through sluggish attentional shifting (SAS) in all sensory modalities. However, the amodality assumption of the SAS theory was never straightforwardly assessed in the same group of dyslexic participants using similar paradigms in both the visual and auditory modalities. Here, the attentional sequential performance of control and dyslexic participants was evaluated using rapid serial presentation paradigms measuring individual stream segregation thresholds in the two modalities. The first experiment conducted on French dyslexic children with a phonological disorder revealed an SAS only in the auditory modality only which was strongly related to reading performance. The second experiment carried out on British dyslexic young adults with a phonological disorder using the same auditory segregation task but a different visual paradigm revealed an SAS in both the visual and the auditory modalities. In addition, a relationship was found in this group between SAS, poor reading and poor phonological skills. Two further control experiments showed that differences in task design or participants' language between Experiments 1 and 2 could not account for the differences in terms of visual segregation patterns. Overall, our results support the view that the auditory SAS plays a role in developmental dyslexia via its impact on phonological abilities. In addition, a visual temporal disorder in dyslexia might emerge at a later developmental stage, when the visual system normally becomes more expert at rapid temporal processing.

Resolução temporal de crianças escolares

OBJETIVO: estudar a resolução temporal de crianças com desenvolvimento normal no teste de detecção de intervalos de silêncio (Random gap detection - RGDT) e no teste de detecção do intervalo no ruído (Gaps-in-noise - GIN). MÉTODOS: a população foi composta por 73 crianças escolares, sendo selecionadas 19 com desenvolvimento normal, na faixa etária de seis a 14 anos, de ambos os sexos, ausência de histórico otológico e/ou audiológico e de queixas escolares; audição normal; produção articulatória de todos os sons do Português e sem distúrbios do processamento auditivo. Os procedimentos da pesquisa foram os testes RGDT e GIN, realizados a 50 dB NS sendo o primeiro apresentado binaural e o segundo monoauralmente. Para análise dos dados foi aplicado teste t de Student. RESULTADOS: no teste RGDT, a média dos intervalos de silêncio para as freqüências de 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz foram respectivamente, 10,13 ms; 8,69 ms; 11,94 ms; 10,56 ms, não ocorrendo diferenças estatisticamente significantes em relação à freqüência testada. No teste GIN, a média do limiar foi de 5,7 ms para a orelha direita e 5,4 ms para a orelha esquerda, não havendo diferença estatisticamente significante quanto à orelha avaliada. CONCLUSÃO: há evidências de diferenças dos limiares dos testes, o que aponta a hipótese de que GIN e RGDT não estejam avaliando a mesma habilidade auditiva ou requisitem processos não auditivos nas tarefas solicitadas. Desta forma, são necessárias novas pesquisas para entender melhor a aplicabilidade e os parâmetros de ambos os testes na prática clínica no Brasil.

Stimulus, task, and learning effects on measures of temporal resolution: implications for predictors of language outcome

PURPOSE

Some studies find that temporal processing ability predicts language outcome whereas other studies do not. Resolution of this debate is hindered by the variety of temporal measures used, nonsensory loading of the tasks, and differential amounts of practice across studies. The goal of this study was to examine the effects of stimulus properties, experimental task, and perceptual learning on listeners' gap detection performance.

METHOD

Gap detection thresholds were obtained from adults with normal hearing and language ability. The effects of marker frequency similarity and marker duration on thresholds were examined in yes-no, two-interval forced-choice (2IFC), and dual-pair comparison tasks (which vary in nonsensory loading) over 4 days of testing.

RESULTS

Thresholds were highest for gaps defined by markers with disparate frequencies (1000 and 4000 Hz; i.e., between-channel gap detection), and with longer (300 ms) trailing markers, obtained using yes-no and 2IFC tasks. However, these effects were attenuated with training or the initial use of the dual-pair comparison task.

CONCLUSIONS

These results suggest that gap detection thresholds reflect a variety of sensory and nonsensory factors. Understanding these underlying factors is critical to any evaluation of the relation between temporal processing and language outcome.

A few remarks on relating reaction time to magnocellular activity

Studies have found dyslexic readers to have longer reaction times than nondyslexic readers. These results have been discussed relative to the hypothesis that dyslexia is caused by a magnocellular deficit. We here point out that attempts to link reaction times in dyslexic readers to magnocellular sensitivity face at least two serious problems: (a) The reaction time differences between dyslexics and controls appear too large to be attributable to deficits in the magnocellular system; (b) there is evidence to suggest that in the case of stimuli with contrast above about 10% behavioral reaction times may reflect parvocellular rather than magnocellular activity.

Resolução temporal: análise em pré-escolares nascidos a termo e pré-termo

TEMA: processamento auditivo. OBJETIVO: verificar o comportamento auditivo de resolução temporal de crianças na faixa etária de cinco a seis anos, nascidas pré-termo, sem evidências de alterações neurológicas e compará-lo com o mesmo comportamento auditivo de crianças na mesma faixa etária, nascidas a termo, com baixo risco para alteração do desenvolvimento, considerando as variáveis: limiar de detecção de intervalo de tempo por freqüência sonora pré-estabelecida apresentada na forma binaural e monoaural por ordem de orelha que iniciou o teste e gênero. MÉTODO: 70 sujeitos: 44 nascidos a termo reunidos em grupos de 20 indivíduos do sexo feminino e 24 do sexo masculino, denominado Grupo 1, e 26 nascidos pré-termo, sendo 12 indivíduos do sexo feminino e 14 do sexo masculino, denominado Grupo 2, foram submetidos a avaliação audiológica composta por audiometria tonal limiar, limiar de reconhecimento de fala, imitânciometria e aplicação do teste de fusão auditiva denominado de Random Gap Detection. RESULTADOS: os nascidos a termo apresentaram menores limiares de detecção de intervalo de tempo no teste de fusão auditiva, nas formas de apresentação binaural e monoaural em todas as freqüências sonoras pré-estabelecidas, do que os nascidos pré-termo com diferença estatisticamente significante. As médias dos limiares de detecção de intervalo de tempo do Grupo 1 aumentaram conforme a freqüência sonora aumentou. No Grupo 2 não foram encontradas diferenças estatisticamente significantes quanto as médias de limiares de detecção de intervalo de tempo na forma de apresentação binaural e monoaural. CONCLUSÃO: os nascidos pré-termo se diferenciam dos nascidos a termo quanto ao comportamento auditivo de resolução temporal e o teste de fusão auditiva utilizado pode servir como ferramenta para a avaliação do processamento auditivo, uma vez que a detecção precoce de alteração dos processos temporais indica uma intervenção para minimizar ou evitar futuros prejuízos de linguagem.

Development of perceptual correlates of reading performance

Performance on perceptual tasks requiring the discrimination of brief, temporally proximate or temporally varying sensory stimuli (temporal processing tasks) is impaired in some individuals with developmental language disorder and/or dyslexia. Little is known about how these temporal processes in perception develop and how they relate to language and reading performance in the normal population. The present study examined performance on 8 temporal processing tasks and 5 language/reading tasks in 120 unselected readers who varied in age over a range in which reading and phonological awareness were developing. Performance on all temporal processing tasks except coherent motion detection improved over ages 7 years to adulthood (p<0.01), especially between ages 7 and 13 years. Independent of these age effects, performance on all 8 temporal processing tasks predicted phonological awareness and reading performance (p<0.05), and three auditory temporal processing tasks predicted receptive language function (p<0.05). Furthermore, all temporal processing measures except within-channel gap detection and coherent motion detection predicted unique variance in phonological scores within subjects, whereas only within-channel gap detection performance explained unique variance in orthographic reading performance. These findings partially support the (Farmer, M.E., Klein, R.M., 1995. The evidence for a temporal processing deficit linked to dyslexia: A review. Psychon. Bull. Rev. 2, 460-493) notion of there being separable auditory and visual perceptual contributions to phonological and orthographic reading development. The data also are compatible with the view that the umbrella term "temporal processing" encompasses fundamentally different sensory or cognitive processes that may contribute differentially to language and reading performance, which may have different developmental trajectories and be differentially susceptible to pathology.

Ordenação e resolução temporal em cantores profissionais e amadores afinados e desafinados

TEMA: ordenação e resolução temporal. OBJETIVO: comparar o desempenho de cantores que recebem orientação profissional, cantores amadores independentes e cantores amadores desafinados nos testes de padrão de freqüência sonora e teste de detecção de gap (Random Gap Detection Test). MÉTODO: participaram 78 indivíduos, de ambos os gêneros, com idade variando entre 18 e 55 anos. Foram incluídos cantores com audição normal, comprovada por meio de exame audiológico e com ausência de queixas de linguagem, fala, voz ou audição. Cada indivíduo respondeu a um questionário fornecendo várias informações, entre elas, a sua própria percepção auditiva sobre sua voz cantada; o tempo de canto com orientação profissional, dificuldade para cantar novas músicas e o de estudo de teoria musical. Para a avaliação foram utilizados o Teste de Padrão de Freqüência Sonora (TPF) e o Teste de Detecção de Gap Randomizado (RGDT) a fim de avaliar as habilidades de ordenação temporal e a resolução temporal respectivamente. RESULTADOS: no que se refere ao teste de detecção de gap randomizado (RGDT) não houve diferença estatisticamente significante entre as respostas por grupo e por variável. Em relação ao desempenho do TPF foi observado que o grupo que recebe orientação profissional possui desempenho superior e estatisticamente significante em relação ao grupo de amadores independentes e estes melhor do que o grupo de amadores desafinados. O desempenho no teste de padrão de freqüência teve relação com o treinamento especializado e com o estudo de teoria musical. CONCLUSÃO: o teste de detecção de gap (RGDT) não se mostrou sensível para distinguir cantores com orientação profissional de amadores, ao contrário do teste de padrão de freqüência sonora. O desempenho no teste de padrão de freqüência reflete o maior treinamento auditivo especializado e de estudo de teoria musical.

Rapid visual processing by college students in reading irregular words and phonologically regular pseudowords presented singly and in contiguity

Using normal adult readers, this study examined the relative involvement of magnocellular and parvocellular processes in reading English phonologically regular pseudowords and irregular words presented in isolation and in contiguity from left to right. The data showed that a low temporal frequency visual measure that implied more parvocellular involvement was active in processing irregular words presented singly and pseudowords presented in contiguity. However, the results failed to show the involvement of the magnocellular pathway (as implicated by low spatial and/or high temporal frequency visual measures) in reading words presented in contiguity from left to right. The discrepancy was discussed in terms of the sensitivity of the tasks used in testing the two pathways.

Development of auditory saltation and its relationship to reading and phonological processing

PURPOSE

The temporal offset of auditory saltation is thought to be reflective of the limits of temporal resolution, and has recently been used to compare dyslexic and control adults and children, with mixed results (R. Hari & P. Kiesilä, 1996; M. Kronbichler, F. Hutzler, & H. Wimmer, 2002). This study sought to document and understand normative changes in saltation thresholds as a function of age, and examine the relationship of saltation thresholds to reading and phonological processing across development.

METHOD

This study used a cross-sectional developmental design. Groups of 7-8-, 9-10-, and 11-13-year-old children, and adults, undertook a 2-alternative forced-choice saltation task, along with standard tests of reading and phonological processing.

RESULTS

Significantly higher and more variable saltation thresholds were evident in the 7-8-year-old group. Group distributions were skewed: Only a few young children obtained poor thresholds while most showed adult-like performance. Saltation thresholds were not related to reading or phonological processing skills at any stage of development.

CONCLUSIONS

The temporal offset of saltation is unlikely to reflect the true limits of temporal resolution in young children, but rather the conflation of perceptual and nonperceptual factors (such as poor short-term memory, inattention, and confusion) to task performance. Effort should be made to minimize such nonperceptual factors, particularly when using saltation as a measure of temporal resolution in participants with dyslexia.

Assessing the role of different spatial frequencies in word perception by good and poor readers

Numerous studies indicate that dyslexic and nondyslexic individuals exhibit different patterns of sensitivity to spatial frequency. However, the extension of this effect to normal (nondyslexic) adults of good and poor reading abilities and the role played by different spatial frequencies in word perception have yet to be determined. In this study, using normal (nondyslexic) adults, we assessed reading ability, spatial frequency sensitivity, and perception of spatially filtered words and nonwords (using a two-alternative forced choice paradigm to avoid artifactual influences of nonperceptual guesswork). Good and poor readers showed different patterns of spatial frequency sensitivity. However, no differences in accuracy of word and nonword perception were found between good and poor readers, despite their differences in spatial frequency sensitivity. Indeed, both reading abilities showed the same superior perceptibility for spatially filtered words over nonwords across different spatial frequency bands. These findings indicate that spatial frequency sensitivity differences extend to normal (nondyslexic) adult readers and that a range of spatial frequencies can be used for word perception by good and poor readers. However, spatial frequency sensitivity may not accurately reveal an individual's ability to perceive words.

Poor readers of Chinese respond slower than good readers in phonological, rapid naming, and interval timing tasks

The role of information processing deficits in poor readers of nonalphabetic scripts such as Chinese is not well documented. Here, we examined perceptual processing in good and poor readers of Chinese. Specifically, two groups of third grade children comprising 20 "good readers" and 19 "poor readers," drawn from a larger pool of 254 students, were tested using an auditory version of the Stop Reaction Time (Stop-RT) interval timing task, a phoneme perception task, and several measures of phonological awareness and orthographic processing. Mean Stop RTs for good readers were significantly faster than those for poor readers, and good readers were also faster in a test of rapid digit naming, but good and poor readers did not differ on measures of phoneme onset awareness or orthographic processing. Although good and poor readers did not differ in overall categorical perception of /pa5/ and /pha5/ stimuli, the good readers responded significantly faster than the poor readers. Taken together, the group differences obtained here are consistent with a slowing of information processing and behavioral output in poor readers of Chinese, rather than a loss of temporal resolution of perceptual processing.

Sources of errors on visuoperceptual tasks: role of education, literacy, and search strategy

The current study explored possible sources of demographic effects through analyses of errors from modified formats of the Benton Visual Retention Test (BVRT) completed by African American elders. Results indicate that: (1) reading level was a stronger predictor of BVRT performance than years of education; (2) on the single-item matching format of the task, individuals with lower reading levels disproportionately produced errors on items that differed in geometric, rather than spatial features; and (3) on a multiple-choice matching format, individuals with lower reading levels committed more errors on items where the target was located in the lower half of a 2 x 2 matrix.

Dyslexia and dysgraphia: more than written language difficulties in common

A dual-task paradigm involving concurrent finger tapping and line orientation judgment was used to investigate brain processing differences in early adolescent good readers/poor spellers (dysgraphia), poor readers/poor spellers (dyslexia) and good readers/good spellers. Whereas all groups were similarly affected during the left-hand tapping condition, in the right-hand tapping condition the good spelling group displayed significantly less tapping disruption than both poor spelling groups, who did not differ significantly from each other. From these results, it can be inferred that individuals with dyslexia and dysgraphia share a left-hemisphere processing limitation that is not confined to written language. In light of other relevant research findings, I suggest that this limitation is due to the absence of a disembedding scanning mechanism for converting spatial arrays (e.g., spelling patterns) to temporal form-an impairment putatively caused by attempting to teach written language to children who are late in establishing left-hemisphere motor dominance.

The role of visual and auditory temporal processing in reading irregular and nonsense words

In the present study, the role of rapid visual and auditory temporal processing in reading irregular and nonsense words was investigated with a group of normal readers. One hundred and five undergraduates participated in various visual and auditory temporal-processing tasks. Readers who primarily adopted the phonological route in reading (nonsense-word readers) showed a trend for better auditory temporal resolution but readers who primarily adopted sight word skills (irregular-word readers) did not exhibit better visual temporal resolution. Both the correlation and stepwise multiple-regression analyses, however, revealed a relationship between visual temporal processing and irregular-word reading as well as a relationship between auditory temporal processing and nonsense-word reading. The results support the involvement of visual and auditory processing in reading irregular and nonsense words respectively, and were discussed with respect to recent findings that only dyslexics with phonological impairment will display temporal deficits. Further, the temporal measures were not effective discriminants for the reading groups, suggesting a lack of association between reading ability and the choice of reading strategy.

Auditory processing and the development of language and literacy

This paper considers evidence for basic auditory processing impairments associated with dyslexia and specific language impairment, against a back-drop of findings from studies of the normal development of auditory and phonological processing. A broad range of auditory impairments have been implicated in the aetiology of these language-learning disorders, including deficits in discriminating the temporal order of rapid sequences of auditory signals, elevated thresholds for frequency discrimination and for detection of amplitude and frequency modulation, impaired binaural processing and increased susceptibility to backward masking. Current evidence is inconsistent, but suggests that not all children with language difficulties have non-verbal auditory processing impairments, and for those that do, the impact on language development is poorly understood. Some implications for clinical practice are discussed.

Temporal order and processing acuity of visual, auditory, and tactile perception in developmentally dyslexic young adults

We studied the temporal acuity of 16 developmentally dyslexic young adults in three perceptual modalities. The control group consisted of 16 age- and IQ-matched normal readers. Two methods were used. In the temporal order judgment (TOJ) method, the stimuli were spatially separate fingertip indentations in the tactile system, tone bursts of different pitches in audition, and light flashes in vision. Participants indicated which one of two stimuli appeared first. To test temporal processing acuity (TPA), the same 8-msec nonspeech stimuli were presented as two parallel sequences of three stimulus pulses. Participants indicated, without order judgments, whether the pulses of the two sequences were simultaneous or nonsimultaneous. The dyslexic readers were somewhat inferior to the normal readers in all six temporal acuity tasks on average. Thus, our results agreed with the existence of a pansensory temporal processing deficit associated with dyslexia in a language with shallow orthography (Finnish) and in well-educated adults. The dyslexic and normal readers' temporal acuities overlapped so much, however, that acuity deficits alone would not allow dyslexia diagnoses. It was irrelevant whether or not the acuity task required order judgments. The groups did not differ in the nontemporal aspects of our experiments. Correlations between temporal acuity and reading-related tasks suggested that temporal acuity is associated with phonological awareness.

Multisensory prior entry

Despite 2 centuries of research, the question of whether attending to a sensory modality speeds the perception of stimuli in that modality has yet to be resolved. The authors highlight weaknesses inherent in this previous research and report the results of 4 experiments in which a novel methodology was used to investigate the effects on temporal order judgments (TOJs) of attending to a particular sensory modality or spatial location. Participants were presented with pairs of visual and tactile stimuli from the left and/or right at varying stimulus onset asynchronies and were required to make unspeeded TOJs regarding which stimulus appeared first. The results provide the strongest evidence to date for the existence of multisensory prior entry and support previous claims for attentional biases toward the visual modality and toward the right side of space. These findings have important implications for studies in many areas of human and animal cognition.