抑制能力在學齡前階段具有顯著的進展。過去的研究發現，前額葉受損的兒童（例如：注意力不足暨過動症兒童）在二種類型的抑制能力，衝突解決和動作反應抑制能力的表現較差。因此，本研究主要探討衝突解決和動作反應抑制能力。許多發展性研究顯示，和抑制能力相關的前額葉區域在學齡前階段持續的發展成熟，但卻鮮少有研究探討學齡前階段孩童衝突解決和動作反應抑制能力發展與大腦神經發展之間的關係。 本研究利用兒童版的旁側抑制作業（Flanker task）和停止信號作業（Stop signal task）探討五、六歲孩童的衝突解決和動作反應抑制能力的行為表現和事件相關腦電波。實驗一探討五、六歲孩童執行兒童版旁側抑制作業的一致性效果和N2效果。結果發現五、六歲孩童均觀察到一致性效果和N2效果，但一致性效果和N2效果卻沒有隨著年齡的增長而有顯著性的進展。實驗二探討五、六歲孩童執行停止信號作業時，針對停止信號所需的反應時間和N2成分。行為結果發現看到停止信號時，五歲孩童相較於六歲孩童需要花費較長的時間停止動作反應。然而，五、六歲孩童執行停止信號作業時，在成功動作抑制和失敗成功抑制情境均沒有觀察到N2成分，卻觀察到晚期正向波形（late positive wave）在失敗動作抑制情境較成功抑制情境的振幅大。晚期正向波形反映的是錯誤反應所誘發的正向錯誤成分（error positivity）。此結果顯示五、六歲孩童執行停止訊號作業時，尚未發展出反映動作抑制歷程的N2成分。另一方面晚期正向波形的出現，顯示五、六歲孩童知道自己按錯鍵，且可能開始對此錯誤反應進行改善。 Inhibitory control has a significant improvement in preschool period. Conflict monitoring and motor response inhibition both are types of inhibitory control, and children with frontal lobe dysfunctions, such as attention-deficit hyperactivity children (ADHD), show deficits in these two types of inhibitory control. Many developmental studies have indicated that the prefrontal lobe cortex, which is a region that plays an important role in the inhibitory control, continues mature in preschool stage. However, few studies have integrated the neural correlates of inhibitory control with the development of conflict monitoring and motor response inhibition in typically developing preschool children. In this thesis, a child version of the flanker task and the stop signal task were used to investigate the behavioral performance and the corresponding event-related potentials (ERPs) of conflict monitoring and motor response inhibition in 5 and 6 years of age. In Experiment 1, we assessed whether congruency effect and the N2 effect were detectable when preschool children performed the child version of the flanker task. Our results showed that the congruency effect and N2 effect (350 - 500 ms) were observed in 5- and 6-years-old children, but did not improve with age between 5 and 6 years. In Experiment 2, we measured the stop signal reaction time (SSRT) and the N2 effect in the stop signal task with 5 and 6 years old preschoolers. The behavioral results indicated that the response inhibition significantly improved with age in 5 and 6 years old. However, we did not observe significant N2 (250 - 450 ms) difference between the successful inhibition condition and the failed inhibition condition in our preschoolers. Instead, we observed that a late positive wave (500 - 900 ms) was more positive-going in the failed inhibition than in the successful inhibition. Late positive component in preschoolers can be associated with the processing of an error event that has been referred to as “error positivity” or Pe. These results suggest that the processes of the inhibitory control indexed by the N2 component have not yet been well-developed when 5 and 6 years old preschoolers performed the stop signal task. On the other hand, it seems that the preschoolers are in the processing of developing the cognitive capability in error detection and correction, as reflected by the late positive component.
