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posted by janrinok on Sunday February 03 2019, @02:13PM   Printer-friendly
from the but-I-haven't-got-a-tiny-eye dept.

Submitted via IRC for Bytram

Tiny eye movements affect how we see contrast

Researchers previously believed contrast sensitivity function -- the minimum level of black and white that a person needs to detect a pattern -- was mainly dictated by the optics of the eye and processing in the brain. Now, in a study published in the journal eLife, researchers, including Michele Rucci at the University of Rochester, explain that there is another factor at play: contrast sensitivity also depends on small eye movements that a person is not even aware of making.

"Historically these movements have been pretty much ignored," says Rucci, a professor of brain and cognitive sciences at Rochester. "But what seems to be happening is that they are contributing to vision in a number of different ways, including our contrast sensitivity function."

When we fix our eyes on a single point, the world may appear stable, but at the microscopic level, our eyes are constantly jittering. These small eye movements, once thought to be inconsequential, are critical to the visual system in helping us reconstruct a scene, Rucci says. "Some scientists believed that because they are so small, the eye movements might not have much impact, but compared to the size of the photoreceptors on the retina, they are huge, and they are changing the input on the retina."

Think of a scene or object like a computer image made up of different pixels, or points. Each point is a different color, intensity, luminance, and so on. Our eyes take in signals from each of the points and project the signals onto photoreceptors on the retina: the arrangement of these points makes a spatial pattern that we perceive as a scene or object. But, if a spatial pattern is projected as a stationary image, it will fade from view once the retina's photoreceptors become desensitized to the signal -- like a student who becomes bored in class if the teacher repeats the same information over and over again.

Researchers have long known that the tiny eye movements -- always jittering and taking in different points -- continually change the signal to the retina and refresh the image so it does not fade. The new research suggests, however, that these movements do more than prevent fading; they are one of the very mechanisms by which the visual system functions, Rucci says. "The way the visual system encodes information is based on these temporal changes. Eye movements transform a spatial pattern into temporal changes on the retina."

[...] Knowing that eye movements do affect contrast sensitivity, researchers are able to input this factor into models of human vision, providing more accuracy in understanding exactly how the visual system processes information -- and what can go wrong when the visual system fails. The research also highlights that movement and motor behavior may be more fundamental to vision than previously thought, Rucci says. "Vision isn't just taking an image and processing it via neurons. The visual system uses an active scheme to extract and encode information. We see because our eyes are always moving, even if we don't know it."

Antonino Casile, Jonathan D Victor, Michele Rucci. Contrast sensitivity reveals an oculomotor strategy for temporally encoding space. eLife, 2019; 8 DOI: 10.7554/eLife.40924


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  • (Score: 0) by Anonymous Coward on Monday February 04 2019, @08:16AM (2 children)

    by Anonymous Coward on Monday February 04 2019, @08:16AM (#796040)

    There's a forum for that [stackexchange.com]i

  • (Score: 2) by Runaway1956 on Monday February 04 2019, @08:22AM (1 child)

    by Runaway1956 (2926) Subscriber Badge on Monday February 04 2019, @08:22AM (#796042) Journal

    Yes - and?

    I already knew that the person who linked to that story the first time lurked around SN.

    • (Score: 0) by Anonymous Coward on Monday February 04 2019, @01:41PM

      by Anonymous Coward on Monday February 04 2019, @01:41PM (#796120)

      Just trying to be full of help :-(