School of Psychology, University of Birmingham, Birmingham, UK.
Department of Forensic and Neurodevelopmental Science, Kings College London, London, UK.
Sci Rep. 2017 Jul 6;7(1):4785. doi: 10.1038/s41598-017-05011-x.
Competition between simultaneously presented visual stimuli lengthens reaction time and reduces both the BOLD response and neural firing. In contrast, conditions of sequential presentation have been assumed to be free from competition. Here we manipulated the spatial proximity of stimuli (Near versus Far conditions) to examine the effects of simultaneous and sequential competition on different measures of working memory (WM) for colour. With simultaneous presentation, the measure of WM precision was significantly lower for Near items, and participants reported the colour of the wrong item more often. These effects were preserved when the second stimulus immediately followed the first, disappeared when they were separated by 500 ms, and were partly recovered (evident for our measure of mis-binding but not WM precision) when the task was altered to encourage participants to maintain the sequentially presented items together in WM. Our results show, for the first time, that competition affects the measure of WM precision, and challenge the assumption that sequential presentation removes competition.
同时呈现的视觉刺激会延长反应时间,并降低大脑活动的血氧水平依赖(BOLD)反应和神经放电。相比之下,人们认为顺序呈现的条件不会产生竞争。在这里,我们操纵了刺激的空间接近程度(近距和远距条件),以检查同时和顺序竞争对颜色工作记忆(WM)的不同测量指标的影响。在同时呈现的情况下,近距项目的 WM 精度指标明显较低,参与者报告错误项目的颜色的次数也更多。当第二个刺激紧随第一个刺激时,这些效应得以保留;当它们被隔开 500 毫秒时,这些效应消失;当任务被改变以鼓励参与者将顺序呈现的项目一起保持在 WM 中时,这些效应部分恢复(我们的绑定错误测量指标明显,但 WM 精度指标不明显)。我们的结果首次表明,竞争会影响 WM 精度的测量指标,这挑战了顺序呈现可消除竞争的假设。