视觉P300与反应时间的概率效应

Visual P300 and reaction time:probability effect

报告了30名受试者在按键应答高(P=0.70),低(P=0.15)概率出现的靶刺激时的视觉P300、反应时间及它们相关程度的变化。结果显示,高概率靶刺激可引出额叶P300而与低概率靶刺激的顶叶P300的头皮分布不同。在相同刺激概率条件下,反应时间短于P300潜伏期。高概率靶刺激的P300潜伏期及反应时间短于低概率靶刺激的相应指标。低概率靶刺激的P300潜伏期与反应时间相关显著而高概率靶刺激的却无相关。因此靶刺激概率的变化既影响刺激评价阶段又影响反应的选择,组织与执行阶段,概率效应可能反映了被试者反应策略的调整。

Effect of probability by changing the probability of target stimuli between 0.15 ( the rare ) and 0.70 ( the frequent ) was investgated with a choice RT task of three visual stimuli. The latency of parietal P300 elicited by the rare lasts longer than that of the frontal P300 elicited by the frequent.And the RT of the rare is longer than that of the frequent. P300 latency is significantly correlated with RT in the rare. No correlation was found between the two in the frequent. The probability effect may influence both stages of stimulus evaluation and response. These findings may suggest the varying strategies of the subjects.