Abstract
Our eyes move constantly. Even when we try to fixate our gaze, we produce "fixational" eye movements, including microsaccades, drift and tremor. Fixational eye movements are thought to be critical to vision, but no studies have quantified their separate impacts on preventing versus restoring visual loss during fixation. Recently, we showed that microsaccades are the most important eye movement contributor to restoring faded vision during fixation (McCamy et al., 2012). Here we modified our previous method and used it to calculate the microsaccade efficacy and contribution to preventing visual fading. We recorded the eye movements of human observers while they reported, via button press, when foveal and peripheral visual targets faded or intensified perceptually. We defined the contribution of microsaccades (and other eye movements) to preventing visual fading, as the percentage of fading preventions caused by microsaccades (and other eye movements), and the efficacy of microsaccades as the percentage of microsaccades that prevented fading. Our data show that both microsaccades and drift contribute to preventing faded foveal and peripheral vision, but that microsaccades are more effective. Microsaccades prevent both foveal and peripheral fading in an equivalent fashion, and microsaccadic sizes, numbers, and directions are equally effective at preventing fading. These combined results indicate that microsaccades and drift work together to prevent fading, and that drift alone does not prevent fading perpetually, thus microsaccades are necessary. Microsaccades do not occur at all times, however, and so the oculomotor system must achieve a delicate balance between microsaccades and drift to prevent and restore faded vision. REFERENCE: McCamy, M. B., Otero-Millan, J., Macknik, S. L., Yang, Y., Troncoso, X. G., Baer, S. M., Crook, S. M., et al. (2012). Microsaccadic Efficacy and Contribution to Foveal and Peripheral Vision. The Journal of Neuroscience, 32(27), 9194–9204. doi:10.1523/JNEUROSCI.0515-12.2012
Meeting abstract presented at VSS 2013