Department of Psychology, Tsinghua University, Haidan, Beijing, China.
Biol Psychol. 2010 Sep;85(1):171-8. doi: 10.1016/j.biopsycho.2010.06.008. Epub 2010 Jul 3.
The earliest cortical location at which attention influences visual processing is controversial. To address this issue, the C1 and P1 components of cue-elicited ERPs were examined in a spatially-cued task under high and low levels of attentional load (active vs. passive viewing). Cues were presented either to the left or to the right visual field in separate trials (unilateral presentation), or to both visual fields simultaneously (bilateral presentation). For the unilateral presentation, C1 (peak latency approximately 80 ms) was not modulated by attentional load, whereas P1 (peak latency approximately 120-140 ms) was larger for high-relative to low-load condition. Bilateral presentation of the stimuli enhanced the amplitude of the C1 component relative to unilateral presentation; however, the increase of signal/noise ratio of C1 revealed no attentional load effect on C1. Results show that attentional load modulates visual processing in the P1, but not in the C1 time range, regardless of the increased signal/noise ratio by bilateral presentation. While it remains unclear about the conditions under which a C1 attentional effect is reliably elicited, the present results suggest that the direct manipulation of attentional load under a voluntary attention task seems not crucial for eliciting C1 attentional effect.
注意对视觉加工产生影响的最早皮质区存在争议。为解决这一问题，本研究在高、低注意负载（主动观看与被动观看）条件下，利用空间线索诱发电位（ERP）的 C1 和 P1 成分，对空间线索任务进行了检测。线索分别在单侧呈现（单侧呈现）或双侧呈现（双侧呈现）的不同试验中呈现于左或右视野。对于单侧呈现，注意负载并未调制 C1（峰潜伏期约 80ms），但 P1（峰潜伏期约 120-140ms）在高负载条件下的振幅大于低负载条件。与单侧呈现相比，刺激的双侧呈现增强了 C1 成分的振幅；然而，C1 的信号/噪声比增加并未揭示出 C1 上的注意负载效应。结果表明，无论双侧呈现增加了信号/噪声比，注意负载均会调制 P1 时间范围内的视觉加工，但不会调制 C1 时间范围内的视觉加工。虽然目前尚不清楚在何种条件下可以可靠地诱发出 C1 注意效应，但本研究结果表明，在自愿注意任务下直接操纵注意负载似乎对于诱发出 C1 注意效应并非至关重要。
