Micromovements during fixation - the eyes are never completely still. In this example, the observer was asked to fixate a certain location in the scene for 4 sec. Left panel: gaze trace from start to end of fixation. Right panel: The current gaze position is projected to the center of the plot, and the underlying image displays the 45 x 45 min arc scene region around the current point of gaze. Notably, the eye moves toward the object (a “floating” trumpet).

Data were recorded from the right eye with an SR Research EyeLink system running at 1000 Hz. In the animation, real-time eye movements are slowed down by factor 20. The raw gaze data (left panel) and the retinal image (right panel) are updated every 5 ms. The scene was provided by Melissa Võ.

Do these involuntary microsaccades serve any useful purpose? For an affirmative review see Engbert (2006), for a critical review see Collewijn & Kowler (2008).