How we see the world is generated in the brain. Over hundreds of thousands of years, our perception has helped shape our cognitive ability, allowing us to evolve into social and empathetic beings. It also alters our expectation of reality, which – as optical illusions never fail to prove – isn’t always what we think it is.
Yale University researchers remind us just how unreliable our perspective can be. As part of the Neural Correlate Society's annual optical illusion contest, researchers placed two dots on a moving map of Tokyo. At first, it appears as if the red dot is chasing the blue, but about 30 seconds into the video it looks like the blue dot starts chasing the red.
However, the red dot is actually stationary and the blue dot moves around it in a repeating animation. In the background, the map moves and shifts position. Halfway through the experiment, researchers reverse the direction of the map, which makes it look as though the blue dot begins to chase the red.
The illusion shows how our brain assigns human characteristics such as "intentionality" and "animacy" to inanimate objects.
“Although researchers have traditionally focused on the motions of objects, what may really matter is how those objects move with respect to the surrounding scene,” wrote study author Benjamin van Buren in a blog post. “Here we demonstrate how a movement that signals animacy in one context may be perceived radically differently in the context of another scene.”
Check out the video for yourself, but be sure to have the volume up. The commentary is hilarious.
The second half of the video shows the movement of the dots when layered over a black background. Here, it’s easy to understand the central red disc isn’t moving, while the peripheral blue disc moves around it haphazardly.
“The primary goals of this study were to identify cues that trigger the perception of chasing, to quantify their influence, and to objectively evaluate the accuracy of this form of perception,” wrote the authors in the Journal of Vision. To do this, researchers split study participants into two groups. The first group saw the background move generally as if the discs were moving over it in tandem, with the red disc always behind the blue. For the other half, the background moved generally along the vector from the central to the peripheral disc. The first group reported perceiving the red dot as chasing the blue, while the second experienced the reverse.
The Neural Correlate Society says studying illusions like this helps deepen our understanding of sensory perception and helps inform what we know about visual and neurological diseases.