Strauch Christoph, Koniakowsky Ina, Huckauf Anke
General Psychology, Ulm University, DE.
J Cogn. 2020 Mar 27;3(1):7. doi: 10.5334/joc.96.
In our physical environment as well as in many experimental paradigms, we need to decide whether an occurring stimulus is relevant to us or not; further, stimuli have uneven probabilities to emerge. Both, decision making and the difference between rare and frequent stimuli (oddball effect) are described to affect pupil dilation. Surprisingly though, conjoint systematic pupillometric investigations into both factors are still rare. In two experiments, both factors as well as their interplay were investigated. Participants completed a sequential letter matching task. In this task, stimulus probability and letter matching (decision making) were manipulated independently. As dependent variables, pupil dilation and reaction time were assessed. Results suggest a clearly larger pupil dilation for target than for distractor letters, even when targets were frequent and distractors rare. When considering the data structure best, no main effect of stimulus probability was found, instead, oddball effects only emerged when stimuli were goal-relevant to participants. The results are discussed in the light of common theoretical concepts of decision making and stimulus probability. Finally, relating theories of each factor, we propose an integrated framework for effects of decision making and stimulus features on pupil dilation. We assume a sequential mechanism during which incoming stimuli are decided upon regarding their goal relevance and, about 200 ms later, relevant stimuli are appraised regarding their value.
在我们的物理环境以及许多实验范式中，我们需要判断出现的刺激是否与我们相关；此外，刺激出现的概率并不均匀。据描述，决策以及罕见刺激与频繁刺激之间的差异（奇异球效应）都会影响瞳孔扩张。然而，令人惊讶的是，对这两个因素进行联合系统的瞳孔测量研究仍然很少见。在两项实验中，对这两个因素及其相互作用进行了研究。参与者完成了一个连续字母匹配任务。在这个任务中，刺激概率和字母匹配（决策）是独立操纵的。作为因变量，评估了瞳孔扩张和反应时间。结果表明，即使目标频繁而干扰项罕见，目标字母的瞳孔扩张也明显大于干扰项字母。在最佳考虑数据结构时，未发现刺激概率的主效应，相反，奇异球效应仅在刺激与参与者的目标相关时出现。根据决策和刺激概率的常见理论概念对结果进行了讨论。最后，结合每个因素的理论，我们提出了一个关于决策和刺激特征对瞳孔扩张影响的综合框架。我们假设存在一种顺序机制，在此机制中，对于传入的刺激，首先判断其与目标的相关性，大约200毫秒后，对相关刺激的价值进行评估。
