Do Rare Stimuli Evoke Large P3s by Being Unexpected? A Comparison of Oddball Effects Between Standard-Oddball and Prediction-Oddball Tasks.
Do Rare Stimuli Evoke Large P3s by Being Unexpected? A Comparison of Oddball Effects Between Standard-Oddball and Prediction-Oddball Tasks.
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DOI：
10.5709/acp-0189-9
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发表时间：
2016
影响因子：
1.2
通讯作者：
Śmigasiewicz K
中科院分区：
文献类型：
--
作者：
Verleger R;Śmigasiewicz K
当很少出现刺激时，事件相关电位的P3成分增加。人们一直认为，这种奇怪的效应(罕见-频繁的差异)反映了罕见刺激的意想不到。这里检验了出乎意料的假设及其与P3波幅的联系。将需要对频繁和罕见的刺激做出不同按键反应的标准古怪任务与古怪预测任务进行比较，后者必须首先预测刺激，然后通过按键确认。预测任务中的奇怪效果取决于是否预测了频繁或罕见的刺激。在标准古怪任务中，古怪对P3波幅和错误率的影响与频繁预测后的效果非常相似。这证实了这样一种观点，即这些影响的发生是因为频繁的刺激是预期的，而罕见的刺激是意想不到的。然而，仔细观察预测任务，就会对这一概念产生怀疑，因为预期对P3的奇怪影响完全是由于对频繁刺激的影响，而由罕见刺激引起的大P3幅度对预测不敏感(与反应时间和错误率不同)。因此，罕见的刺激不能说能唤起大的P3波幅，因为它们是意想不到的。关于P3b功能的概念和假设，我们讨论了频率和期望的这些不同的影响，以及任务之间的一般差异，并得出结论，每个讨论的概念或假设都遇到了一些问题，一个分配给刺激的主观关联性的概念对这些基本影响提供了最一致的解释。
The P3 component of event-related potentials increases when stimuli are rarely presented. It has been assumed that this oddball effect (rare-frequent difference) reflects the unexpectedness of rare stimuli. The assumption of unexpectedness and its link to P3 amplitude were tested here. A standard- oddball task requiring alternative key-press responses to frequent and rare stimuli was compared with an oddball-prediction task where stimuli had to be first predicted and then confirmed by key-pressing. Oddball effects in the prediction task depended on whether the frequent or the rare stimulus had been predicted. Oddball effects on P3 amplitudes and error rates in the standard oddball task closely resembled effects after frequent predictions. This corroborates the notion that these effects occur because frequent stimuli are expected and rare stimuli are unexpected. However, a closer look at the prediction task put this notion into doubt because the modifications of oddball effects on P3 by expectancies were entirely due to effects on frequent stimuli, whereas the large P3 amplitudes evoked by rare stimuli were insensitive to predictions (unlike response times and error rates). Therefore, rare stimuli cannot be said to evoke large P3 amplitudes because they are unexpected. We discuss these diverging effects of frequency and expectancy, as well as general differences between tasks, with respect to concepts and hypotheses about P3b’s function and conclude that each discussed concept or hypothesis encounters some problems, with a conception in terms of subjective relevance assigned to stimuli offering the most consistent account of these basic effects.