Boy Frederic, Sumner Petroc
Department of Psychology, College of Human and Health Science, Swansea University-Singleton Campus.
School of Psychology, Cardiff University.
J Exp Psychol Gen. 2014 Jun;143(3):1011-25. doi: 10.1037/a0034881. Epub 2013 Nov 4.
With resurgent interest in individual differences in perception, cognition and behavioral control as early indicators of disease, endophenotypes, or a means to relate brain structure to function, behavioral tasks are increasingly being transferred from within-subject settings to between-group or correlational designs. The assumption is that where we know the mechanisms underlying within-subject effects, these effects can be used to measure individual differences in those same mechanisms. However, between-subjects variability can arise from an entirely different source from that driving within-subject effects, and here we report a clear-cut demonstration of this. We examined the debated relationship between the visibility of a masked-prime stimulus and the direction of priming it causes (positive or reversed). Such reversal of priming has been hypothesized to reflect an automatic inhibitory mechanism that controls partially activated responses and allows behavioral flexibility. Within subjects, we found an unambiguous systematic transition from reversed priming to positive priming as prime visibility increased, replicated 7 times, and using different stimulus manipulations. However, across individuals there was never a relationship between prime discrimination ability and priming. Specifically, these data resolve the controversial debate on visibility and reversed priming, indicating that they arise from independent processes relying on partially shared stimulus signals. More generally, they stand as an exemplar case in which variance between individuals arises from a different source from that produced by stimulus manipulations.
随着人们对感知、认知和行为控制方面的个体差异作为疾病早期指标、内表型或联系脑结构与功能的一种手段的兴趣再度兴起，行为任务正越来越多地从个体内部设置转移到组间或相关设计中。假设是，在我们了解个体内部效应背后的机制的情况下，这些效应可用于测量相同机制中的个体差异。然而，个体间的变异性可能源于与驱动个体内部效应完全不同的来源，在此我们报告对此的一个明确例证。我们研究了被掩蔽启动刺激的可见性与其所引起的启动方向（正向或反向）之间存在争议的关系。这种启动的反转被假设为反映一种自动抑制机制，该机制控制部分激活的反应并允许行为灵活性。在个体内部，我们发现随着启动刺激可见性增加，从反向启动到正向启动存在明确的系统转变，重复了7次，并使用了不同的刺激操作。然而，在个体之间，启动刺激辨别能力与启动之间从未存在关系。具体而言，这些数据解决了关于可见性和反向启动的争议性辩论，表明它们源于依赖部分共享刺激信号的独立过程。更一般地说，它们代表了一个典型案例，其中个体间的差异源于与刺激操作产生的差异不同的来源。
