Current models of perceptual decision-making assume that choices are made after evidence in favor of an alternative accumulates to a given threshold. This process has recently been revealed in human EEG recordings, but an unresolved issue is how these neural mechanisms are modulated by competing, yet task-irrelevant, stimuli. In this study, we tested 20 healthy participants on a motion direction discrimination task. Participants monitored two patches of random dot motion simultaneously presented on either side of fixation for periodic changes in an upward or downward motion, which could occur equiprobably in either patch. On a random 50% of trials, these periods of coherent vertical motion were accompanied by simultaneous task-irrelevant, horizontal motion in the contralateral patch. Our data showed that these distractors selectively increased the amplitude of early target selection responses over scalp sites contralateral to the distractor stimulus, without impacting on responses ipsilateral to the distractor. Importantly, this modulation mediated a decrement in the subsequent buildup rate of a neural signature of evidence accumulation and accounted for a slowing of RTs. These data offer new insights into the functional interactions between target selection and evidence accumulation signals, and their susceptibility to task-irrelevant distractors. More broadly, these data neurally inform future models of perceptual decision-making by highlighting the influence of early processing of competing stimuli on the accumulation of perceptual evidence.

中文翻译：

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干扰器选择性地调节感知决策的电生理标记。

当前的感知决策模型假设选择是在支持替代方案的证据累积到给定阈值后做出的。这个过程最近在人类脑电图记录中得到揭示，但一个悬而未决的问题是这些神经机制是如何被竞争但与任务无关的刺激所调节的。在这项研究中，我们测试了 20 名健康参与者的运动方向辨别任务。参与者监测同时出现在注视两侧的两个随机点运动斑块，以确定向上或向下运动的周期性变化，这可能在任一斑块中发生。在随机 50% 的试验中，这些连贯的垂直运动周期伴随着对侧斑块中同时与任务无关的水平运动。我们的数据表明，这些干扰物选择性地增加了对干扰物刺激对侧头皮部位的早期目标选择反应的幅度，而不影响干扰物同侧的反应。重要的是，这种调制介导了证据积累的神经特征的后续积累率的下降，并解释了 RT 的减慢。这些数据为目标选择和证据积累信号之间的功能相互作用以及它们对与任务无关的干扰因素的敏感性提供了新的见解。更广泛地说，这些数据通过突出竞争刺激的早期处理对感知证据积累的影响，在神经上为未来的感知决策模型提供信息。