返回抑制和抑制标签在长时训练下的分离

返回抑制(Inhibition of return, IOR)是指当线索-靶子的时隔大于约300 ms时, 被试对呈现在线索化位置的靶子相较对出现在非线索化位置的靶子而言反应更慢的现象。新近抑制标签 (Inhibitory tagging, IT) 理论指出, 除返回抑制外, 一个由前额叶执行控制系统负责的抑制标签机制也作用于先前线索化位置, 起着暂时中断刺激-反应链接的作用。然而, 迄今为止, 该理论的关键假设-“抑制标签一定程度上独立于返回抑制发挥作用”还未有来自常规被试研究的支持。结合线索-靶子和Stroop范式, 采用8(训练天数)×2(线索-靶子关系)×3(色字一致性)的三因素被试内实验设计, 通过连续8天的长时训练对常规被试的返回抑制和抑制标签功能在学习可塑性上的差别进行考察。结果发现, 返回抑制随着练习的增加呈现出了显著降低的趋势, 而抑制标签并未随着练习的变化而变化。研究结果表明返回抑制和抑制标签在一定程度上可以相互分离, 为抑制标签理论的关键假设提供了重要的来自常规被试的证据。

Dissociation of Inhibitory Tagging from Inhibition of Return by Long-term Training

Inhibition of return (IOR) refers to slower responses to targets presented at the previously attended location than to those at control locations. A recent theory suggests that aside from IOR, a mechanism called inhibitory tagging (IT), also works on previously attended locations to temporarily block the perceptual representations accessing its appropriate response. Due to its capability of explaining many complex interactions between IOR and other effects (e.g., the interaction between IOR and Stroop effect), the IT theory has received more and more attention in the recent literature. However, till now, no direct evidence of the dissociation between IOR and IT has been observed in healthy normal participants. In the present study, we tried to dissociate IT from IOR in healthy normal participants by using of a long-term training procedure. 21 healthy participants (2 male, 19 female, with mean age of 22±3.03) were required to finish a task combined the cue-target paradigm and Stroop task in 8 successive days. Specifically, in each training day, the participants were asked to react as fast and accurate as possible to the displayed color of Stroop stimuli (color words) presented at either the cued or uncued locations. Results showed that: 1) the IOR effect decreased significantly as the training days increased in both the traditional RTs difference index (RTcued – RTuncued, p = 0.01) or the RTs ration index (RTuncued /RTcued, p < 0.05). 2) In contrast to the IOR effect, the inhibitory tagging indexed by the interaction between IOR and Stroop effect didn’t show significant decrease with the increased training days. 3) Both the semantic and the response conflict effect expressed a significant decrease trend as the training days extended to 8-days. Taken together, those findings suggest that 1) IT could be dissociated from IOR, providing the first evidence for the dissociation between IT and IOR in heathy participants; 2) IOR could be affected reliably by 8-days training, supporting the “lack of enough training” explanation for the previous inconsistent results about the practice effect of IOR; and 3) at odds with previous studies regarding practice effect of conflict processing (e.g., Chen et al. 2010), the current results suggest that training, at least as long as 8-days training, could affect both the semantic and response conflict.