Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Langeveld Building, Room H0.26, Heidelberglaan 1, 3584 CS, Utrecht, The Netherlands.
Sci Rep. 2021 Jan 12;11(1):707. doi: 10.1038/s41598-020-80286-1.
Pupillometry has received increased interest for its usefulness in measuring various sensory processes as an alternative to behavioural assessments. This is also apparent for multisensory investigations. Studies of the multisensory pupil response, however, have produced conflicting results. Some studies observed super-additive multisensory pupil responses, indicative of multisensory integration (MSI). Others observed additive multisensory pupil responses even though reaction time (RT) measures were indicative of MSI. Therefore, in the present study, we investigated the nature of the multisensory pupil response by combining methodological approaches of previous studies while using supra-threshold stimuli only. In two experiments we presented auditory and visual stimuli to observers that evoked a(n) (onset) response (be it constriction or dilation) in a simple detection task and a change detection task. In both experiments, the RT data indicated MSI as shown by race model inequality violation. Still, the multisensory pupil response in both experiments could best be explained by linear summation of the unisensory pupil responses. We conclude that the multisensory pupil response for supra-threshold stimuli is additive in nature and cannot be used as a measure of MSI, as only a departure from additivity can unequivocally demonstrate an interaction between the senses.
瞳孔测量技术因其在测量各种感觉过程方面的有用性而受到越来越多的关注，可作为行为评估的替代方法。这在多感官研究中也很明显。然而，多感官瞳孔反应的研究产生了相互矛盾的结果。一些研究观察到超加性多感官瞳孔反应，表明存在多感官整合 (MSI)。其他研究观察到加性多感官瞳孔反应，尽管反应时间 (RT) 测量表明存在 MSI。因此，在本研究中，我们通过结合以前研究的方法学方法，同时仅使用超阈值刺激，来研究多感官瞳孔反应的性质。在两个实验中，我们向观察者呈现听觉和视觉刺激，这些刺激在简单的检测任务和变化检测任务中引起了（起始）反应（无论是收缩还是扩张）。在两个实验中，RT 数据表明存在 MSI，如种族模型不等式违反所示。尽管如此，两个实验中的多感官瞳孔反应都可以通过对单一感觉瞳孔反应的线性求和来最好地解释。我们得出结论，超阈值刺激的多感官瞳孔反应本质上是相加的，不能作为 MSI 的衡量标准，因为只有偏离加性才能明确证明感官之间的相互作用。
