Many people have not realized that in our daily lives, we naturally blink every few seconds. Unless we are engaged in competitions where the goal is to see who can keep their eyes open without blinking for a longer duration, in which case tears accumulate continuously until we can no longer resist the urge to blink. When our eyelids close for an instant, our eyeballs are moisturized. However, the function of blinking goes far beyond simply moistening the eyeball; research has found that our blinking frequency exceeds the need for maintaining eye moisture.
After a series of studies aiming to reveal the multiple functions of blinking, a recent study shows that blinking is also beneficial to vision. “Blinking can enhance retinal stimulation, thereby significantly improving visibility,” write neuroscientists from the University of Rochester in a paper published in the Proceedings of the National Academy of Sciences. Previous research had suggested that blinking can enhance attention, aid object recognition, and segment the continual flow of visual and auditory information into separate slices for better processing.
Although we may not be aware of it, every blink actually comes with about 300 milliseconds of temporary blindness, which might lead one to think could interrupt or even negatively affect neuronal processing of visual input. Yet, amazingly, a study from 2016 pointed out that neuronal activity indeed decreases when we close our eyes, but once we blink, neuronal activity rebounds to a higher level, and this mechanism is thought to enhance vision.
Based on these findings, the research team at the University of Rochester invited 12 subjects to view images with different contrasts in a new study, while using high-resolution eye-tracking technology to study the impact of blinking on vision. Since our eyes usually blink in sync, researchers tracked only one eye and recorded the changes in light intensity in the visual input. The results showed that as compared to continuously staring at a screen, blinking can enhance visual input signals by regulating the intensity of light that falls on the retina. This was confirmed both when subjects were instructed to blink and when they blinked spontaneously.
Unlike previous studies that revealed only an actual blink could enhance attention, new research further discovered that even light changes produced by simulated blinks could temporarily improve vision. The researchers stressed, “Blinking is not detrimental to visual processing as often thought, but instead improves visual sensitivity.”
In addition to this, blinking can also help reset the formatting of visual signals, similar to other involuntary eye movements such as rapid eye jumps and eye drifts, which shape our visual experience by adding spatial and temporal markers in the visual information. Realizing that we spend about 10% of our waking time blinking, and that this action is actually beneficial to us, is indeed comforting.
