School of Psychology, Bangor University, Bangor, Gwynedd, United Kingdom.
J Exp Psychol Hum Percept Perform. 2012 Apr;38(2):478-88. doi: 10.1037/a0025979. Epub 2011 Nov 7.
When participants repeat the same task in a context in which the task may also switch (a mixed block), performance deteriorates compared to when there is only one task repeating (a pure block). Three experiments were designed to assess how perceptual and motor transitions influenced this mixing cost. Experiment 1 provided three pure block baselines for perceptual and motor transitions. Experiments 2 and 3 examined these transitions in a mixed block. Results show that most of the mixing cost comes from two factors: (a) episodic interference in the mixed block when the stimulus changes and the response repeats, and (b) increased suppression in mixed blocks affecting trials where stimulus-response mappings repeat. We propose that these mechanisms are strategically applied when adopting a sustained "switching set" in mixed blocks. The purpose of this set would be to avoid perseveration errors in the most demanding trials (the task-switching trials), but remaining active during task-repetitions. Results regarding the mixing cost are thus relevant to the assessment of models of task-switching, which at present mainly rely on data from task switch trials.
当参与者在可能也会切换任务的环境中重复相同的任务（混合块）时，与只有一个任务重复（纯块）相比，表现会恶化。设计了三个实验来评估感知和运动转换如何影响这种混合成本。实验 1 为感知和运动转换提供了三个纯块基线。实验 2 和 3 在混合块中检查了这些转换。结果表明，大部分混合成本来自两个因素：（a）在混合块中，当刺激发生变化且反应重复时，情节干扰；（b）在混合块中，对刺激-反应映射重复的试验的抑制增加。我们提出，当在混合块中采用持续的“切换集”时，这些机制会被策略性地应用。该集合的目的是避免在最具挑战性的试验（任务切换试验）中出现持续错误，但在任务重复期间保持活跃。因此，关于混合成本的结果与任务切换模型的评估有关，目前这些模型主要依赖于任务切换试验的数据。
