Shafer Valerie L, Ponton Curtis, Datta Hia, Morr Mara L, Schwartz Richard G
Speech and Hearing Sciences, The Graduate Center, CUNY, NY, USA.
Clin Neurophysiol. 2007 Jun;118(6):1230-43. doi: 10.1016/j.clinph.2007.02.023. Epub 2007 Apr 23.
The aim was to determine whether children with specific language impairment (SLI) differed from children with typical language development (TLD) in their allocation of attention to speech sounds.
Event-related potentials were recorded to non-target speech sounds in two tasks (passive-watch a video and attend to target tones among speech sounds) in two experiments, one using 50-ms duration vowels and the second using 250-ms vowels. The difference in ERPs across tasks was examined in the latency range of the early negative difference wave (Nd) found in adults. Analyses of the data using selected superior and inferior sites were compared to those using electrical field power (i.e., global field power or GFP). The topography of the ERP at the maximum GFP was also examined.
A negative difference, comparable to the adult Nd, was observed in the attend compared to the passive task for both types of analysis, suggesting allocation of attentional resources to processing the speech stimuli in the attend task. Children with TLD also showed greater negativity than those with SLI in the passive task for the long vowels, suggesting that they allocated more attentional resources to processing the speech in this task than the SLI group. This effect was only significant using the GFP analysis and was seen as smaller GFP for the TLD than SLI group. The SLI group also showed significantly later latency than the TLD group in reaching the maximum GFP. In addition, a significantly greater proportion of children with SLI compared to those with typical language showed left-greater-than-right frontocentral amplitude at the latency determined from each child's maximum GFP peak.
Children generally showed greater attention to speech sounds when attention is directed to the auditory modality compared to the visual modality. However, children with TLD, unlike SLI, also appear to devote some attentional resources to speech even in a task in which they are instructed to attend to visual information and ignore the speech.
These findings suggest that children with SLI have limited attentional resources, that they are poorer at dividing attention, or that they are less automatic in allocating resources to speech compared to children with typically developing language skills.
旨在确定特定语言障碍（SLI）儿童与语言发育正常（TLD）儿童在对语音的注意力分配上是否存在差异。
在两项实验中的两项任务（被动观看视频并在语音中关注目标音调）中记录与非目标语音相关的电位，一项实验使用时长50毫秒的元音，另一项使用时长250毫秒的元音。在成人中发现的早期负向差异波（Nd）的潜伏期范围内，检查不同任务之间ERP的差异。使用选定的上、下位部位对数据进行的分析与使用电场功率（即全局场功率或GFP）的分析进行比较。还检查了最大GFP处ERP的地形图。
在两种分析类型中，与被动任务相比，在关注任务中均观察到与成人Nd相当的负向差异，这表明在关注任务中注意力资源被分配用于处理语音刺激。对于长元音，TLD儿童在被动任务中也比SLI儿童表现出更大的负向性，这表明他们在该任务中比SLI组分配了更多的注意力资源来处理语音。这种效应仅在使用GFP分析时显著，并且表现为TLD组的GFP比SLI组小。SLI组在达到最大GFP时的潜伏期也明显比TLD组长。此外，与语言发育正常的儿童相比，SLI儿童中在由每个儿童的最大GFP峰值确定的潜伏期时，左额中央振幅大于右额中央振幅的比例显著更高。
与视觉模态相比，当注意力指向听觉模态时，儿童通常对语音表现出更多关注。然而，与SLI儿童不同，TLD儿童即使在被指示关注视觉信息并忽略语音的任务中，似乎也会将一些注意力资源投入到语音上。
这些发现表明，与语言技能正常发育的儿童相比，SLI儿童的注意力资源有限，他们在注意力分配方面较差，或者在将资源分配到语音方面不太自动。
