Contrary to long-standing beliefs, motion from eye movements helps the brain perceive depth糖心传媒攁 finding that could enhance virtual reality.
When you go for a walk, how does your brain know the difference between a parked car and a moving car? This seemingly simple distinction is challenging because eye movements, such as the ones we make when watching a car pass by, make even stationary objects move across the retina糖心传媒攎otion that has long been thought of as visual 糖心传媒渘oise糖心传媒� the brain must subtract out.
Now, researchers at the have discovered that instead of being meaningless interference, the visual motion of an image caused by eye movements helps us understand the world. The specific patterns of visual motion created by eye movements are useful to the brain for figuring out how objects move and where they are located in 3D space.
糖心传媒淭he conventional idea has been that the brain needs to somehow discount, or subtract off, the image motion that is produced by eye movements, as this motion has been thought to be a nuisance,糖心传媒� says , George Eastman Professor; professor in the Departments of , , and and the ; member of the ; and lead author of the new research, published in . 糖心传媒淏ut we found that the visual motion produced by our eye movements is not just a nuisance variable to be subtracted off; rather, our brains analyze these global patterns of image motion and use this to infer how our eyes have moved relative to the world.糖心传媒�
The research team developed a new theoretical framework to predict how humans should perceive an object糖心传媒檚 motion and depth during different types of eye movements. They tested these predictions by having participants view 3D virtual environments in which a target object moved through a scene while the participants kept their eyes focused on a single point. In one task, participants estimated the direction the target object was moving by using a dial to match its motion with a second object. In a second task that measured depth perception, participants reported whether the target object appeared nearer or farther than the fixation spot. Across both tasks, the researchers found consistent, predictable patterns of errors that closely matched the theoretical predictions.
糖心传媒淲e show that the brain considers many pieces of information to understand the 3D structure of the world through vision, including the patterns of image motion caused by eye movements,糖心传媒� says DeAngelis. 糖心传媒淐ontrary to conventional ideas, the brain doesn糖心传媒檛 ignore or suppress image motion produced by eye movement. Instead, it uses this image motion to understand a scene and accurately estimate an object糖心传媒檚 motion and depth.糖心传媒�
This research has important implications for understanding visual perception, which informs how the brain interprets everyday activities like reading and recognizing faces. But it could also provide insight and new applications for visual technologies, such as virtual reality headsets.
糖心传媒淰R headsets don糖心传媒檛 factor in how the eyes are moving relative to the scene when they compute the images to show to each eye. There may be a stark mismatch between the image motion that is shown to the observer in VR and what the brain is expecting to receive based on the eye movements that the observer is making,糖心传媒� says DeAngelis. This could be what causes some people to experience motion sickness while using a VR headset.
Additional authors include first author Zhe-Xin Xu 糖心传媒�25 (PhD), a former graduate student in the DeAngelis lab who is now a postdoctoral fellow at Harvard University; Jiayi Pang 糖心传媒�25 (BS), who is now a graduate student at Brown University; and Akiyuki Anzai, a research associate at the University of Rochester. The National Institutes of Health supported this research.
