Searching for monocular microsaccades – A red Hering of modern eye trackers?

Despite early reports and the contemporary consensus on microsaccades as purely binocular phenomena, recent work has proposed not only the existence of monocular microsaccades, but also that they serve functional purposes. We take a critical look at the detection of monocular microsaccades from a signal perspective, using raw data and a state-of-the-art, video-based eye tracker. In agreement with previous work, monocular detections were present in all participants using a standard microsaccade detection algorithm. However, a closer look at the raw data invalidates the vast majority of monocular detections. These results again raise the question of the existence of monocular microsaccades, as well as the need for improved methods to study small eye movements recorded with video-based eye trackers.