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

该研究项目探讨了信息处理的本质，没有意识的感知和运动反应，进行了几个实验，使用反应时（RT）任务与后向掩蔽范式，其中启动和掩码刺激被用作命令性刺激。在实验中操纵了启动刺激的强度和SOA（启动刺激和掩蔽刺激之间的刺激起始时间）。为了研究行为方面，我们测量了（1）在两个被迫选择任务中对原始刺激的感知的意识，（2）对命令性刺激集的运动反应的反应时间（素数和掩码），实验结果表明，反应时与S-LRPs潜伏期有一定的相关性反应时与R-LRP潜伏期（从LRP出现到反应开始的时间）无相关性。这表明，启动刺激提前启动了运动信息加工的准备阶段。意识的知觉的主要刺激是明显的长SOA（100毫秒），但不存在的短SOA（32毫秒），表明主要刺激必须掩盖的面具刺激与短（32毫秒）SOA。S-LRP的潜伏期为32毫秒SOA是非常相似的条件下，单独的启动刺激作为一个命令性刺激的S-LRP。这表明无意识感知的启动刺激。促进运动反应，导致反应时间短。然而，一个问题是否促进知觉过程或直接激活运动过程绕过知觉过程的主要刺激，仍然是开放的问题。

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.