Neuroscientists Explain Motion Aftereffect Optical Illusion
Posted on June 28, 2011
Stare at the X in the center of the image in the video above. After a few seconds an image of a yellow jacket, named Rocky (the mascot of the University of Rochester), will appear. Rocky will appear to be expanding, but the image of Rocky is a still image. This is an illusion called Motion Aftereffect. It has been known for many years. It was first documented by Aristotle in 350 B.C. You also experience the illusion when you step of a moving treadmill and temporarily everything around seems to be in motion.
Researchers at the University of Rochester conducted a study that found humans experience the Motion Aftereffect even if the motion that they see in the background is so brief (a fraction of a second) that they can't even tell whether it is heading to the right or the left. The researchers say this discovery means the illusion is caused by neural processes that happen essentially every time we see moving objects.
The researchers plan to do additional studies to see if this rapid motion adaptation serves a beneficial purpose, such as improving your ability to estimate the speed and direction of a baseball flying toward you.
The results of the illusion study will be published this week in the journal Proceedings of the National Academy of Sciences (PNAS).