Microsaccades

Microsaccades are tiny, involuntary eye movements that occur during fixation. They are quick, small-scale shifts in the direction of gaze that typically last for about 20-200 milliseconds.

Characteristics

Microsaccades exhibit the following characteristics:

Size: They involve only a few arcminutes of visual angle and are usually smaller than regular saccades.
Frequency: They occur at a regular rate of 1-2 Hz, although this can vary among individuals.
Direction and amplitude: Microsaccades can be in any direction, including horizontal, vertical, or oblique, and their amplitudes typically range from 5 to 30 arcminutes.
Timing: They tend to occur during periods of prolonged fixation, particularly when attention is focused on a specific object or target.

Function

The exact function of microsaccades is still a subject of scientific debate. Some proposed functions include:

Compensation for retinal image fading: Microsaccades help prevent the visual system from adapting to steady fixation, avoiding the loss of sensitivity in the retinal photoreceptors.
Enhancement of perception: These tiny eye movements have been suggested to improve the quality of visual perception, such as aiding in spatial attention, image stabilization, and information integration.
Exploration and preview: Microsaccades may enable the visual system to gather information by selectively redirecting the gaze to different locations of interest during fixation.
Maintenance of visual acuity: They contribute to keeping the retinal image clear and avoiding the potential blurring that can occur due to fixational drift.

Further research is needed to fully understand the precise role and significance of microsaccades in visual perception and oculomotor control.