Contiguity and overshadowing interactions in the rapid-streaming procedure

Previous research has reported that temporal contiguity is a critical factor determining the direction of cue-interactions: strong contiguity leads to competition (e.g., overshadowing), but weak contiguity leads to no-interaction and sometimes leads to facilitation (e.g., potentiation). In these experiments, we adapted the streamed-trial procedure to further explore this interaction in a preparation in which the presentation of trials occurred in rapid streams. In five experiments we assessed whether contiguity and overshadowing effects are reliably observed in this procedure, and whether there was an interaction between them. Participants had to learn the relationship between visual cues and an outcome. Using within-subject designs, participants experienced independent series of streams in which cues and outcomes were trained either with delay or trace conditioning, and these target cues were presented either alone or with another cue. Across experiments, we consistently observed overshadowing (Experiments 1, 2, 5) and contiguity effects (Experiments 2, 3, 4, 5). Despite the consistency of both effects, we did not find that weakening temporal contiguity abolished competition between cues, although the magnitude of overshadowing was weaker with trace conditioning. This suggests that in the streamed-trial procedure contiguity modulates competition to some extent, but perhaps the parameters and conditions used in here were not adequate to produce a shift from competition to facilitation. Overall, these results suggest that the extent to which contiguity determines cue-interactions depends on multiple variables that we address in the General Discussion.

既往研究表明，时间连续性（temporal contiguity）是决定线索交互（cue-interactions）方向的关键因素：较强的时间连续性会引发竞争效应，例如遮蔽效应（overshadowing）；而较弱的时间连续性则不会产生线索交互，有时甚至会引发易化效应（facilitation），例如potentiation。在本系列实验中，我们对流式试次范式（streamed-trial procedure）进行了适配调整，以在试次以快速流形式呈现的实验情境中进一步探究此类线索交互作用。我们共开展五项实验，旨在评估该范式中能否稳定观测到时间连续性效应与遮蔽效应，以及二者间是否存在交互作用。实验要求被试学习视觉线索与实验结果间的关联关系。我们采用被试内设计（within-subject designs），让被试完成多组独立的流任务：其中线索与结果的训练分别采用延迟条件反射（delay conditioning）或痕迹条件反射（trace conditioning），且目标线索既可单独呈现，也可与另一线索联合呈现。跨所有实验的结果均稳定观测到了遮蔽效应（实验1、2、5）与时间连续性效应（实验2、3、4、5）。尽管两种效应均表现出良好的稳定性，但我们未发现削弱时间连续性会完全消除线索间的竞争，不过痕迹条件反射下的遮蔽效应强度有所减弱。这表明，在流式试次范式中，时间连续性会在一定程度上调节线索间的竞争，但或许本研究采用的实验参数与条件不足以实现从竞争效应到易化效应的转变。总体而言，本研究结果提示，时间连续性对线索交互的影响程度取决于多种变量，相关探讨将在总讨论部分展开。