Comerchero M D, Polich J
Department of Psychology, University of California, San Diego, La Jolla, CA 92037, USA
Brain Res Cogn Brain Res. 1998 Jul;7(1):41-8. doi: 10.1016/s0926-6410(98)00009-3.
A three-stimulus oddball paradigm (target, standard, nontarget) was employed in which subjects responded to an infrequent target, when its discrimination from the frequent standard was difficult. In separate auditory and visual modality conditions, the stimulus characteristics of an infrequent nontarget were manipulated such that its perceptual distinctiveness from the target was varied systematically. For both the low and high distinctiveness conditions, target stimulus P300 amplitude was larger than the nontarget only at the parietal electrode. In contrast, nontarget P3a amplitude was larger and earlier than the target P300 over the frontal/central electrode sites. The distinctiveness manipulation between the target and nontarget produced larger P3a component profiles for the auditory compared to visual stimuli. The results support previous findings that target/standard stimulus context determines P3a generation for both auditory and visual stimulus modalities and suggest that the distinctiveness of the eliciting stimulus contributes to P3a amplitude. Theoretical implications are discussed.
采用了一种三刺激偏差范式（目标、标准、非目标），当难以将不常见的目标与常见的标准区分开时，让受试者对不常见的目标做出反应。在单独的听觉和视觉模态条件下，对不常见非目标的刺激特征进行操纵，使其与目标在感知上的差异系统地变化。对于低差异和高差异条件，目标刺激的P300波幅仅在顶叶电极处大于非目标。相比之下，在额叶/中央电极部位，非目标的P3a波幅比目标P300更大且更早出现。与视觉刺激相比，目标与非目标之间的差异操纵在听觉刺激中产生了更大的P3a成分特征。这些结果支持了先前的研究发现，即目标/标准刺激背景决定了听觉和视觉刺激模态下P3a的产生，并表明引发刺激的差异有助于P3a波幅。讨论了理论意义。
