Backward masking in a somatosensory reaction-time task and nonconscious motor information-processing

该研究项目研究了没有意识和运动反应的感知基础信息处理的本质，使用反应时间（RT）任务和后向掩蔽范式进行了多项实验，其中启动刺激和掩蔽刺激被用作命令性刺激。实验中操纵了初始刺激的强度和 SOA（初始刺激和掩模刺激之间的刺激开始异步）。为了检查行为方面，我们测量了（1）双强制选择任务中对主要刺激的感知意识，（2）作为对命令性刺激集（主要和掩模）的运动反应的反应时间，以及（3）根据平均脑电图波计算的侧化准备电位（LRP）。实验结果表明，反应时间往往与 S-LRP 的潜伏期（从刺激开始到刺激最初升高的经过时间）相关。 LRP），而 R-LRP 的潜伏期（从 LRP 出现到反应开始的经过时间）与反应时间无关。这表明主要刺激在运动信息处理阶段较早启动，以准备运动反应。对于长 SOA（100 毫秒），对主要刺激的感知意识很明显，但对于短 SOA（32 毫秒）则不存在，这表明主要刺激必须被短（32 毫秒）SOA 的掩模刺激所掩盖。 32 毫秒 SOA 的 S-LRP 的延迟与仅将主要刺激呈现为命令性刺激的条件下的 S-LRP 的延迟非常相似。这表明无意识地感知到主要刺激。促进运动反应，从而缩短反应时间。然而，主要刺激是否促进知觉过程，或者直接激活绕过知觉过程的运动过程，仍然有待商榷。

This research project examined the nature of information processing underlying perception without awareness and motor responses, conducting several experiments using reaction time (RT) tasks with a backward masking paradigm in which a prime and mask stimuli were used as imperative stimuli. Both the intensity of the prime stimulus and SOA (stimulus onset asynchrony between the prime and mask stimulus) were manipulated in the experiments. To examine behavioral aspects we measured (1)the awareness of perception of the prime stimulus in a two-forced-choice task, (2)reaction times as motor responses to the imperative stimulus set (prime and mask), and (3) lateralized readiness potentials (LRPs) which were calculated on the basis of averaged EEG waves.Results of experiments showed that reaction times tended to be correlated with the latency of S-LRPs (the elapsing time from the stimulus onset to the initial raise of the LRPs), whereas the latency of R-LRPs (the elapsing time from the onset of LRPs to the onset of responses) was not correlated with reaction times. This suggested that the prime stimulus initiated earlier the stage of motor information processing for the preparation of motor responses. Awareness of perception of the prime stimulus was evident for a long SOAs (100 ms) but was absent for a short SOAs (32 ms), indicating the prime stimulus must be masked by the mask stimulus with the short (32-ms) SOA. The latency of S-LRPs for the 32-ms SOA was quite similar to that of the S-LRPs under conditions where a prime stimulus alone was presented as an imperative stimulus. This suggested that non-consciously perceived prime stimulus. facilitated motor responses, resulting in short reaction times. However, an issue whether the prime stimulus facilitates the perceptual processes or rather directly activates the motor processes bypassing the perceptual processes, was still open to question.