Department of Psychology, University of A Coruña, Campus de Elviña, La Coruña, 15071, Spain.
Brain Topogr. 2011 Jan;23(4):385-91. doi: 10.1007/s10548-010-0160-z. Epub 2010 Aug 18.
We investigated the effects of stimulus presentation rates on local contextual processing. Local context was defined as the occurrence of a short predictive series of stimuli occurring before delivery of a target event. EEG was recorded in 12 subjects during two sessions: a slower (150 ms stimulus presentation, 1,000 ms interstimulus interval (ISI)) and a faster session (50 ms stimulus presentation, 800 ms ISI). Stimuli were presented to either the left or right visual field and consisted of 15% targets (downward facing triangle) and 85% of equal numbers of three types of standards (triangles facing left, upwards and right). Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences including a predictive sequence signaling the occurrence of a subsequent target event. Subjects pressed a button in response to targets. Reaction times were faster for predicted compared to random targets in both sessions. Faster presentation rates of stimuli induced a greater P3b latency shift between predicted and random targets compared to slower presentation rates, such that P3b latency for predicted targets was shorter in the faster task compared to the slower task. These findings suggest that as stimulus presentation rates increase, predictive local context is utilized to a greater extent, increasing decision confidence in the detection of targets.
我们研究了刺激呈现率对局部上下文处理的影响。局部上下文被定义为在目标事件发生之前出现的短预测系列刺激的发生。在两个会话期间，对 12 个受试者进行了 EEG 记录：一个较慢的（150ms 刺激呈现，1000ms 刺激间间隔（ISI））和一个较快的会话（50ms 刺激呈现，800ms ISI）。刺激呈现于左或右视野，并由 15%的目标（朝下的三角形）和 85%的相等数量的三种标准（向左、向上和向右的三角形）组成。记录块由目标前面的标准随机序列和包括预测序列的序列组成，该预测序列指示随后目标事件的发生。受试者在目标出现时按下按钮。与随机目标相比，在两个会话中，预测目标的反应时间更快。与较慢的呈现率相比，刺激呈现率的加快导致预测和随机目标之间的 P3b 潜伏期偏移更大，从而使预测目标的 P3b 潜伏期在较快的任务中比在较慢的任务中更短。这些发现表明，随着刺激呈现率的增加，预测性局部上下文被更广泛地利用，从而提高了对目标检测的决策信心。
