McBride Jennifer, Sumner Petroc, Husain Masud
1 Institute of Cognitive Neuroscience and Institute of Neurology, University College London, London, UK.
2 School of Biological Sciences, University of Manchester, Manchester, UK.
Q J Exp Psychol (Hove). 2018 Jun;71(6):1431-1439. doi: 10.1080/17470218.2017.1329326. Epub 2018 Jan 1.
Backward-masked primes presented outside conscious awareness can affect responses to subsequently presented target stimuli. Differences in response times have been used to infer a pattern of sub-threshold activation and subsequent inhibition of motor plans associated with the primes. However, it is unclear whether competition between alternative responses is fully resolved in the brain or whether activated responses can begin being executed before the final decision to act has been made. Here, we investigate the dynamics of responses evoked by masked primes using a continuous measure - voltage change in force-sensing resistors simultaneously in both hands. Masked primes produced the predicted pattern of motor activation and subsequent inhibition of the primed response. There is no evidence that the effects of masked primes interact with spatial compatibility (e.g., Simon) effects, suggesting separate mechanisms underpinning these effects. Moreover, masked primes evoked partial motor decisions - measurable at the effectors as small amounts of erroneous response - which were usually rapidly corrected. Together, these errors and fast corrections question the 'sub-threshold' nature of responses evoked by masked primes and provide important constraints on models of decision-making.
呈现于意识觉知之外的逆向掩蔽启动刺激能够影响对随后呈现的目标刺激的反应。反应时间上的差异已被用于推断与启动刺激相关的阈下激活模式以及随后对运动计划的抑制。然而，尚不清楚大脑中替代反应之间的竞争是否能完全解决，或者激活的反应是否能在做出最终行动决定之前就开始执行。在此，我们使用一种连续测量方法——同时测量双手力敏电阻中的电压变化，来研究掩蔽启动刺激诱发的反应动态。掩蔽启动刺激产生了预测的运动激活模式以及随后对启动反应的抑制。没有证据表明掩蔽启动刺激的效应与空间兼容性（如西蒙效应）效应相互作用，这表明支撑这些效应的机制是相互独立的。此外，掩蔽启动刺激诱发了部分运动决策——在效应器上可测量为少量错误反应——这些错误反应通常会迅速得到纠正。这些错误和快速纠正共同对掩蔽启动刺激诱发反应的“阈下”性质提出了质疑，并为决策模型提供了重要限制。
