Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
Cognition. 2010 Apr;115(1):93-103. doi: 10.1016/j.cognition.2009.11.013. Epub 2010 Jan 21.
In this study, we attempted to clarify whether distractibility in ADHD might arise from increased sensory-driven interference or from inefficient top-down control. We employed an attentional filtering paradigm in which discrimination difficulty and distractor salience (amount of image "graying") were parametrically manipulated. Increased discrimination difficulty should add to the load of top-down processes, whereas increased distractor salience should produce stronger sensory interference. We found an unexpected interaction of discrimination difficulty and distractor salience. For difficult discriminations, ADHD children filtered distractors as efficiently as healthy children and adults; as expected, all three groups were slower to respond with high vs. low salience distractors. In contrast, for easy discriminations, robust between-group differences emerged: ADHD children were much slower and made more errors than either healthy children or adults. For easy discriminations, healthy children and adults filtered out high salience distractors as easily as low salience distractors, but ADHD children were slower to respond on trials with low salience distractors than they did on trials with high salience distractors. These initial results from a small sample of ADHD children have implications for models of attentional control, and ways in which it can malfunction. The fact that ADHD children exhibited efficient attentional filtering when task demands were high, but showed deficient and atypical distractor filtering under low task demands suggests that attention deficits in ADHD may stem from a failure to efficiently engage top-down control rather than an inability to implement filtering in sensory processing regions.
在这项研究中，我们试图阐明 ADHD 患者的注意力分散是否是由于增加的感官驱动干扰，还是由于自上而下控制的效率低下引起的。我们采用了注意力过滤范式，其中辨别难度和分心物的显著性（图像“灰度”的程度）是参数化操纵的。增加辨别难度应该会增加自上而下过程的负担，而增加分心物的显著性则会产生更强的感官干扰。我们发现辨别难度和分心物显著性之间存在出乎意料的相互作用。对于困难的辨别，ADHD 儿童与健康儿童和成人一样有效地过滤分心物；正如预期的那样，所有三组对高显著性和低显著性分心物的反应速度都较慢。相比之下，对于容易的辨别，出现了明显的组间差异：ADHD 儿童的反应速度明显较慢，错误率也明显较高。对于容易的辨别，健康儿童和成人像过滤低显著性分心物一样容易过滤高显著性分心物，但 ADHD 儿童对低显著性分心物的反应速度比高显著性分心物慢。这些来自 ADHD 儿童的小样本的初步结果对注意力控制模型以及其可能出现故障的方式具有启示意义。ADHD 儿童在任务要求高时表现出有效的注意力过滤，但在任务要求低时表现出不足和异常的分心物过滤，这表明 ADHD 中的注意力缺陷可能源于无法有效地利用自上而下的控制，而不是无法在感官处理区域实施过滤。
