School of Optometry and Vision Science, The Mina & Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, Israel.
Sci Rep. 2022 Apr 22;12(1):6619. doi: 10.1038/s41598-022-10605-1.
Microsaccades that occur during fixation were studied extensively in response to transient stimuli, showing a typical inhibition (Oculomotor Inhibition, OMI), and a later release with a latency that depends on stimulus saliency, attention, and expectations. Here, we investigated the hypothesis that in free viewing every saccade provides a new transient stimulation that should result in a stimulus-dependent OMI like a flashed presentation during fixation. Participants (N = 16) freely inspected static displays of randomly oriented Gabor texture images, with varied contrast and spatial frequency (SF) for periods of 10 s each. Eye tracking recordings were divided into epochs triggered by saccade landing (> 1 dva), and microsaccade latency relative to fixation onset was computed (msRT). We found that the msRT in free viewing was shorter for more salient stimuli (higher contrast or lower SF), as previously found for flashed stimuli. It increased with saccade size and decreased across successive saccades, but only for higher contrast, suggesting contrast-dependent repetition enhancement in free viewing. Our results indicate that visual stimulus-dependent inhibition of microsaccades also applies to free viewing. These findings are in agreement with the similarity found between event-related and fixation-related potentials and open the way for studies combining both approaches to study natural vision.
我们研究了注视时微扫视对瞬态刺激的反应，结果表明微扫视具有典型的抑制作用（眼动抑制，OMI），且在潜伏期后会释放，潜伏期取决于刺激的显著度、注意力和预期。在这里，我们提出了一个假设，即在自由观看中，每次扫视都会提供新的瞬态刺激，这应该会导致类似于注视时闪烁呈现的刺激依赖性 OMI。参与者（N=16）自由地检查了随机方向的 Gabor 纹理图像的静态显示，每个显示的对比度和空间频率（SF）都不同，持续时间为 10 秒。眼动记录分为扫视结束（>1 dva）触发的时期，计算相对于注视开始的微扫视潜伏期（msRT）。我们发现，与注视时相比，自由观看时更显著的刺激（更高的对比度或更低的 SF）的 msRT 更短，这与之前闪烁刺激的发现一致。它随着扫视大小的增加而增加，随着连续扫视的减少而减少，但仅在更高的对比度下，这表明在自由观看中存在对比度依赖性的重复增强。我们的结果表明，视觉刺激依赖性的微扫视抑制也适用于自由观看。这些发现与事件相关和注视相关电位之间的相似性一致，为结合这两种方法研究自然视觉的研究开辟了道路。
