The color-word Stroop task produces both information conflict (detection of the ink color vs. word meaning) and task conflict (respond to the ink color vs. read the word). In the present study we measured both reaction time and pupil dilation, and the neutral stimuli in our study were non-readable letter strings as well as meaningless non-readable stimuli (i.e., colored patches and abstract character strings). Our results showed slowest responses in the incongruent trials and fastest responses in the congruent trials. However, no differences were found between the investigated neutrals. In contrast, pupil dilation was largest in the incongruent trials and smallest in the neutral trials. Moreover, the more the neutral stimuli were meaningless, the less the pupil dilation that was observed. Our results suggest that non-word meaningless stimuli reduced task conflict (compared to all the investigated conditions). Neutral equivalence should be taken into consideration in Stroop and Stroop-like tasks.

颜色词 Stroop 任务会产生信息冲突（检测墨水颜色与单词含义）和任务冲突（响应墨水颜色与阅读单词）。在本研究中，我们测量了反应时间和瞳孔扩张，我们研究中的中性刺激是不可读的字符串以及无意义的不可读的刺激（即色块和抽象字符串）。我们的结果显示在不一致试验中反应最慢，而在一致试验中反应最快。然而，在被调查的中立者之间没有发现差异。相比之下，瞳孔扩张在不一致的试验中最大，在中性试验中最小。此外，中性刺激越无意义，观察到的瞳孔扩张就越少。我们的结果表明，非单词无意义刺激减少了任务冲突（与所有调查条件相比）。在 Stroop 和 Stroop 类任务中应考虑中性等效。