Schindel Ryan, Rowlands Jemma, Arnold Derek H
School of Psychology, The University of Queensland, St. Lucia, Queensland 4072, Australia.
J Vis. 2011 Feb 24;11(2):17. doi: 10.1167/11.2.17.
When a unique "oddball" stimulus is embedded in a train of repeated standard stimuli, its duration can seem relatively exaggerated (V. Pariyadath & D. Eagleman, 2007; P. U. Tse, J. Intriligator, J. Rivest, & P. Cavanagh, 2004). We explored the possibility of a link between this and signal intensity reductions at low levels of visual processing. In Experiment 1, we used Troxler fading as a metric of signal intensity-the apparent fading of a stimulus with prolonged viewing (I. P. V. Troxler, 1804). Fading was exaggerated by presenting oddball and standard stimuli to different eyes. However, there was no fading difference when standard stimuli were presented persistently or intermittently. These results contrast with oddball effects, which were insensitive to eye of origin, and which were contingent on intermittent standard stimuli. In Experiment 2, we show that oddball effects can be elicited with oddballs that are less intense versions of repetitive stimuli, and in Experiment 3, we show that oddball effects can scale with the discrepancy between repeated and oddball stimuli. These observations discredit any oddball effect explanation predicated on low-level neural response magnitudes to individual stimuli. Instead, our data support the view that oddball effects are driven by predictive coding (V. Pariyadath & D. Eagleman, 2007), reflecting the discrepancy between expected and actual inputs.
当一个独特的“异常”刺激嵌入一系列重复的标准刺激中时，其持续时间可能看起来相对延长（V. Pariyadath和D. Eagleman，2007年；P. U. Tse、J. Intriligator、J. Rivest和P. Cavanagh，2004年）。我们探究了这种现象与低水平视觉处理中信号强度降低之间存在联系的可能性。在实验1中，我们使用特罗克斯勒消退现象作为信号强度的衡量指标——随着注视时间延长，刺激会出现明显消退（I. P. V. Troxler，1804年）。通过向不同眼睛呈现异常刺激和标准刺激，消退现象被放大。然而，当持续或间歇呈现标准刺激时，消退现象并无差异。这些结果与异常刺激效应形成对比，后者对刺激来源的眼睛不敏感，且取决于间歇性标准刺激。在实验2中，我们表明，使用强度低于重复刺激的异常刺激也能引发异常刺激效应，并且在实验3中，我们表明异常刺激效应会随着重复刺激与异常刺激之间的差异而变化。这些观察结果使任何基于对单个刺激的低水平神经反应强度的异常刺激效应解释都站不住脚。相反，我们的数据支持这样一种观点：异常刺激效应是由预测编码驱动的（V. Pariyadath和D. Eagleman，2007年），反映了预期输入与实际输入之间的差异。
