Tanner Darren, Morgan-Short Kara, Luck Steven J
Department of Linguistics, Beckman Institute for Advanced Science and Technology, Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Department of Hispanic and Italian Studies, Department of Psychology, University of Illinois at Chicago, Chicago, Illinois, USA.
Psychophysiology. 2015 Aug;52(8):997-1009. doi: 10.1111/psyp.12437. Epub 2015 Apr 22.
Although it is widely known that high-pass filters can reduce the amplitude of slow ERP components, these filters can also introduce artifactual peaks that lead to incorrect conclusions. To demonstrate this and provide evidence about optimal filter settings, we recorded ERPs in a typical language processing paradigm involving syntactic and semantic violations. Unfiltered results showed standard N400 and P600 effects in the semantic and syntactic violation conditions, respectively. However, high-pass filters with cutoffs at 0.3 Hz and above produced artifactual effects of opposite polarity before the true effect. That is, excessive high-pass filtering introduced a significant N400 effect preceding the P600 in the syntactic condition, and a significant P2 effect preceding the N400 in the semantic condition. Thus, inappropriate use of high-pass filters can lead to false conclusions about which components are influenced by a given manipulation. The present results also lead to practical recommendations for high-pass filter settings that maximize statistical power while minimizing filtering artifacts.
虽然众所周知高通滤波器可以降低慢波ERP成分的幅值，但这些滤波器也可能引入伪峰，从而导致错误的结论。为了证明这一点并提供关于最佳滤波器设置的证据，我们在一个涉及句法和语义违反的典型语言处理范式中记录了ERP。未滤波的结果在语义和句法违反条件下分别显示出标准的N400和P600效应。然而，截止频率在0.3Hz及以上的高通滤波器在真实效应之前产生了相反极性的伪效应。也就是说，过度的高通滤波在句法条件下在P600之前引入了显著的N400效应，在语义条件下在N400之前引入了显著的P2效应。因此，高通滤波器的不当使用可能导致关于哪些成分受给定操作影响的错误结论。目前的结果还为高通滤波器设置提供了实用建议，即在最大限度地提高统计功效的同时最小化滤波伪迹。
