Figure 2

Adaptive selection of saccade threshold. (a) Gaze position across a 2-s trial, classified as “tracking” (green) or “saccade” (red) using the procedure illustrated below. (b) Estimated eye velocity (positive is similar to and negative is opposite to stimulus direction). Grey dashed lines indicate ± 1 saccadic speed threshold. Velocities whose magnitude exceeded the magnitude of the threshold were classed as saccades (red symbols). Black dotted line indicates a linear fit to the tracking data (green symbols) after the first 500 ms; here, the average eye velocity during tracking is 8.8 deg/s (i.e. the y intercept of the fit). The plot on the right shows an adaptive selection of saccade speed threshold from a range of candidate saccade speed thresholds. The plot shows the aggregate displacement of the eye during the trial as the sum of all tracking, minus the sum of all saccade velocities, for each candidate saccade speed threshold. The threshold selected maximised this distance. Adapted from “The Effect of Simulated Visual Field Loss on Optokinetic Nystagmus” by S.M. Doustkouhi et al., 2020, Translational Vision Science & Technology.