Researchers at the University of Queensland are providing insight into why our eyes sometimes play tricks on us.
Motion-induced blindness is a striking visual illusion, in which moving objects can make stationary objects seem to disappear right before your eyes.
The UQ team, from the School of Psychology, has shown that rather than being a failure of vision, this illusion is probably caused by a usually helpful process.
The researchers believed the “trickery” occurred because of the brain’s attempts to help us see moving objects clearly.
PhD candidate Tom Wallis and supervisor Dr Derek Arnold conducted studies that included showing participants displays of moving and stationary dots on a computer screen, and asking them to press buttons to indicate when the stationary objects seemed to disappear.
“A large part of our brain is devoted to interpreting visual input. Visual illusions can tell us something about how our brain processes what we see – we can learn from our brain’s mistakes,” Mr Wallis said.
“In some ways, human vision is a little like a camera with a slow shutter speed. Because of this, objects create streaks when they move.
“The interesting thing is that most of the time we don’t see these streaks.”
Previous research had shown that the brain tried to “rub out” these streaks, by preventing them from reaching our awareness.
“Our experiments suggest that, in this artificial situation, our brain gets confused between motion streaks and stationary objects in a scene,” Mr Wallis said.
“It tries to rub out things it shouldn’t. So an illusion that we might think of as a failure of human vision is probably caused by a process that normally helps us to see clearly defined moving forms.”
The research showed that motion-induced blindness occurred more at the trailing edges, rather than the leading edges of movement.
The results also found that moving objects signalled only by differences in colour, as opposed to brightness, do not have their smears suppressed from awareness. Furthermore, these objects caused almost no motion-induced blindness.
The research findings were published in the journal Current Biology.
(Source: University of Queensland: Current Biology: March 2009)