Department of Psychology, Stanford University, Stanford, CA, USA.
Department of Psychology, University of Chicago, Chicago, IL, USA.
Nat Hum Behav. 2024 Feb;8(2):349-360. doi: 10.1038/s41562-023-01760-0. Epub 2023 Nov 23.
Response times (RTs) are often the main signal of interest in cognitive psychology but are often ignored in functional MRI (fMRI) analyses. In fMRI analysis the intensity of the signal serves as a proxy for the intensity of local neuronal activity, but changes in either the intensity or the duration of neuronal activity can yield identical fMRI signals. Therefore, if RTs are ignored and pair with neuronal durations, fMRI results claiming intensity differences may be confounded by RTs. We show how ignoring RTs goes beyond this confound, where longer RTs are paired with larger activation estimates, to lesser-known issues where RTs become confounds in group-level analyses and, surprisingly, how the RT confound can induce other artificial group-level associations with variables that are not related to the condition contrast or RTs. We propose a new time-series model to address these issues and encourage increasing focus on what the widespread RT-based signal represents.
反应时间 (RTs) 通常是认知心理学中主要的感兴趣信号，但在功能磁共振成像 (fMRI) 分析中经常被忽略。在 fMRI 分析中，信号的强度用作局部神经元活动强度的代理，但神经元活动的强度或持续时间的变化都可能产生相同的 fMRI 信号。因此，如果忽略 RTs 并与神经元持续时间配对，声称强度差异的 fMRI 结果可能会受到 RTs 的混淆。我们展示了忽略 RTs 如何超出这种混淆，其中较长的 RTs 与更大的激活估计值配对，还展示了不太为人知的问题，即 RTs 在组水平分析中成为混淆因素，以及令人惊讶的是，RT 混淆因素如何诱使与条件对比或 RTs 无关的变量产生其他人为的组水平关联。我们提出了一种新的时间序列模型来解决这些问题，并鼓励更多地关注基于 RT 的信号所代表的内容。
