不同意识水平下视觉注意范围提示的事件相关电位研究

ERP study of visual spatial attention under different levels of consciousness

目的:采用“提示―目标”的视觉实验范式,通过事件相关电位(ERP)研究在不同意识水平下,视觉空间注意范围的作用,以进一步了解提示引起视觉注意的脑机制。方法:被试者为18名在校大学生,以大、小2种不同直径的圆圈作为注意范围的区域性提示,让被试者完成视觉搜索任务,并记录反应时与ERP数据。结果:在短提示(40ms)条件下,随着提示等级的增大,反应时延长,早期成分的P1波幅增大,而N1波幅在小提示时最大,N2波幅也在小提示时最大;在长提示(150ms)条件下,结果相同。同时在大、小范围条件下,比较小提示与长提示两种提示条件,P1、N1成分均无显著性差异(P>0.05)。结论:40ms作为感觉阈限时,其提示信息的加工达到了注意范围信息的层次,其加工机制与长提示信息的加工机制相同,只是处于不同意识水平下的自动加工程度不同。

Objective:In the present event-related potential(ERP) study, cue-target tasks were employed to investigate the scale of the visual spatial attention under different levels of consciousness, in order to further understand the brain mechanism of cue-evoked attention. Method: Eighteen under graduates were asked to performed visual search tasks in which the search arrays were preceded by one of the two sizes of circle cues. Reaction times(RT) and ERP components were examined. Result: Reactions slowed down and P1 amplitude enhanced by large cues at a stimulus onset asynchrony(SOA) of 40ms. In contrary, the amplitudes of N1 and N2 decreased as the cue size increased. The results of trials of 150ms SOA were the same as 40ms SOA.The short and long SOA didn′t make any difference in P1 and N1 components under the same cue size.Conclusion: Subliminal special cues modulate neural processing in a function as the cues that can be perceived consciously. Author′s address Institute of Psychology, Chinese Academy of Sciences, Beijing 100101