WEDNESDAY, 7 AUGUST 2013Apparently, yes! According to experiments published in Current Biology by Christopher Berger and Henrik Ehrsson; what you hear can change what you see, what you see can change what you hear, and what you imagine can change both. This is because the human brain processes information from different senses at the same time to construct a representation of the external world. And when these sensory inputs are mismatched, the brain produces a ‘best guess’ that can result in a perception different from reality, called an illusion.
For instance, the classic McGurk Effect showed that volunteers hearing the sound ‘ba’ but watching a mouth form the phoneme ‘ga’ perceived a completely different sound ‘da’. Until now it was thought that such illusions could only be caused by the integration of different senses. But three experiments by Berger and Ehrsson revealed a new source of illusions based on how imagination influences the brain’s perception of events. The first experiment showed that sound imagery can produce a visual illusion. Participants imagined the sound of two circles colliding while watching them collide, then falsely reported seeing the circles bounce off one another. The second experiment showed that visual imagery can create an auditory illusion.
Participants reported hearing sound emanate from the place where they had imagined a white circle – a location different from the true source. In the third experiment, participants imagined the sound ‘ba’ while watching the pronunciation of ‘ga’, and reported hearing the sound ‘da’, similar to the McGurk Effect. This confirmed that mental imagery can create illusions in complex speech. Taken together, these experiments show that our imagination can change real-world perception. This has profound implications for people with psychiatric disorders who have difficulty distinguishing thoughts from reality. This might also help readers empathize with Don Quixote!
Written by Chris Creese.