Our human ability to pinpoint the exact location and size of objects varies from one to another, and even within our own individual field of vision, according to a research released by the University of California, Berkeley (UC Berkeley) on Monday.
The study made by Wang and fellow researchers in UC Berkeley's Whitney Laboratory for Perception and Action was published in the Proceedings of the Royal Society B: Biological Sciences journal.
"We assume our perception is a perfect reflection of the physical world around us, but this study shows that each of us has a unique visual fingerprint," said study lead author Zixuan Wang, a Chinese doctoral student in psychology at UC Berkeley.
For example, a driver who makes even a small miscalculation about the location of a pedestrian crossing the street can cause a catastrophe. Meanwhile, in sports, an error of visual judgment can lead to controversy.
Take, for example, the 2004 U.S. Open quarterfinals, in which tennis player Serena Williams lost to Jennifer Capriati after a series of questionable line calls, resulting in an apology to Williams by the U.S. Tennis Association, according to the study.
"Line judges need to rule on whether the ball is outside or inside the parameters. Even an error as small as half a degree of visual angle, equal to a sub-millimeter shift on the judge's retina, may influence the result of the whole match," said Wang.
Researchers sought to understand if different people see objects in their surroundings exactly the same way. For example, when glancing at a coffee cup on a table, can two people agree on its exact position and whether its handle is big enough to grip? The result of a series of experiments suggests not.
"We may reach for a coffee mug thousands of times in our life, and through practice, we reach our target," Wang said. "That's the behavioral aspect of how we train ourselves to coordinate how we act in relation to what we see."
And in an experiment measuring perception of size, participants viewed a series of arcs of varying lengths and were asked to estimate their lengths. Surprisingly, people perceived the exact same arcs to be bigger at some locations in the visual field and smaller at other locations.
Overall, the results showed remarkable variations in visual performance among the group and even within each individual's field of vision.
"Though our study might suggest that the source of our visual deficiencies can originate from our brain, further investigations are needed to uncover the neural basis," said Wang.
"What's also important is how we adapt to them and compensate for our errors," she added.