Dekkers Tycho J, Agelink van Rentergem Joost A, Koole Alette, van den Wildenberg Wery P M, Popma Arne, Bexkens Anika, Stoffelsen Reino, Diekmann Anouk, Huizenga Hilde M
Department of Psychology, University of Amsterdam, Nieuwe Achtergracht 129B, 1018 WS, Amsterdam, The Netherlands.
Department of Forensic Psychiatry and Complex Behavioral Disorders, Academic Center for Child and Adolescent Psychiatry, De Bascule, Rijksstraatweg 145, 1115 AP, Duivendrecht, The Netherlands.
Eur Child Adolesc Psychiatry. 2017 Dec;26(12):1471-1481. doi: 10.1007/s00787-017-1006-y. Epub 2017 May 23.
Children with attention-deficit/hyperactivity disorder (ADHD) are characterized by deficits in their executive functioning and motivation. In addition, these children are characterized by a decline in performance as time-on-task increases (i.e., time-on-task effects). However, it is unknown whether these time-on-task effects should be attributed to deficits in executive functioning or to deficits in motivation. Some studies in typically developing (TD) adults indicated that time-on-task effects should be interpreted as depletion of executive resources, but other studies suggested that they represent depletion of motivation. We, therefore, investigated, in children with and without ADHD, whether there were time-on-task effects on executive functions, such as inhibition and (in)attention, and whether these were best explained by depletion of executive resources or depletion of motivation. The stop-signal task (SST), which generates both indices of inhibition (stop-signal reaction time) and attention (reaction time variability and errors), was administered in 96 children (42 ADHD, 54 TD controls; aged 9-13). To differentiate between depletion of resources and depletion of motivation, the SST was administered twice. Half of the participants was reinforced during second task performance, potentially counteracting depletion of motivation. Multilevel analyses indicated that children with ADHD were more affected by time-on-task than controls on two measures of inattention, but not on inhibition. In the ADHD group, reinforcement only improved performance on one index of attention (i.e., reaction time variability). The current findings suggest that time-on-task effects in children with ADHD occur specifically in the attentional domain, and seem to originate in both depletion of executive resources and depletion of motivation. Clinical implications for diagnostics, psycho-education, and intervention are discussed.
患有注意力缺陷多动障碍（ADHD）的儿童具有执行功能和动机方面的缺陷。此外，这些儿童的特点是随着任务持续时间的增加表现会下降（即任务持续时间效应）。然而，尚不清楚这些任务持续时间效应应归因于执行功能的缺陷还是动机的缺陷。一些针对发育正常（TD）成年人的研究表明，任务持续时间效应应被解释为执行资源的耗尽，但其他研究表明它们代表动机的耗尽。因此，我们调查了患有和未患有ADHD的儿童，任务持续时间对执行功能（如抑制和注意力）是否有影响，以及这些影响最好用执行资源的耗尽还是动机的耗尽来解释。对96名儿童（42名ADHD儿童，54名TD对照组；年龄9 - 13岁）进行了停止信号任务（SST）测试，该任务可生成抑制指标（停止信号反应时间）和注意力指标（反应时间变异性和错误）。为了区分资源耗尽和动机耗尽，SST进行了两次。一半的参与者在第二次任务执行期间得到强化，这可能抵消动机的耗尽。多层次分析表明，在两项注意力不集中的测量中，患有ADHD的儿童比对照组更容易受到任务持续时间的影响，但在抑制方面则不然。在ADHD组中，强化仅改善了一项注意力指标（即反应时间变异性）。目前的研究结果表明，患有ADHD的儿童的任务持续时间效应特别发生在注意力领域，似乎源于执行资源的耗尽和动机的耗尽。文中讨论了对诊断、心理教育和干预的临床意义。
