19th August 2011 saw the first day of the 3 day Green Man festival held at the Brecon Beacons in the South of Wales. In the vein of most festivals, there was an array of spectacular musical performers of the likes of Tim Minchin and Laura Marling among many others.
At the heart of the festival, in the Einstein’s Garden was a group of Surrey Ph.D. Psychology and Computing research students: Kendi Muchungi (Computing), Christopher Hope and Andrew Pringle (Psychology), headed by Dr. Matthew Casey from the Department of Computing. These research students were dressed in Victorian getup, on a circus looking stage set up in late 19th-century style and were performing perception illusions in a stall named “Cirque de Perception”.
The idea behind “Cirque de Perception” was to introduce festival goers to some of the science behind unusual perception illusions in a fun and simple way so as to capture their imagination and interest. “Cirque de Perception” had four main acts:
The Rubber Hand Illusion: this illusion required a willing participant, whose left hand would then be obscured from their view behind a screen, a rubber hand, positioned in such a way as to mimic their actual left hand and finally, the synchronous stroking of the same finger on the rubber hand and that of the obscured hand over a period of time. Because we derive a sense of self from multiple senses, vision, touch, and proprioception, the manipulation of these senses may cause some restructuring in our brain (neuroplasticity) that results in a temporary transfer of our sense of self to the visible rubber hand.This act actually stole the show in Einstein’s Garden and we had willing punters every single day of the festival. The climax of the show always came when the person stroking the hands would suddenly hit the rubber hand. We had most participants scream or yelp as it took them a few moments to realize that the rubber hand was not their own.
The Stroop Effect: we had four boards with colour names painted in colours that were different to their name. This effect simply showed the interference that takes place in our brains when we are required to shout out the colour of the ink, rather than read the word. This shows that our training to read is so pervasive, that we read automatically even when we don’t need to.The McGurk Effect: for this performance, we had two of the Ph.D. Research students participate, with one hidden out of sight from the audience and the other in full view. The student in full view would mouth a phoneme, say ‘ga’, and the one out of sight would voice, say ‘ba’, and we would then have the audience split up in groups depending on what they thought they heard. Most of the people in the audience tended to hear a phoneme that was neither voiced nor mouthed – ‘da’ – hence the McGurk Effect.
Ventriloquism: for this act, the ability of the ventriloquist Kieran Powell was tested with three Dodo puppets. Kieran would remain on stage while we moved the Dodos around ‘singing’, Old McDonald had a farm, at different locations. This performance was successful because even though the audience knew that Kieran was the ventriloquist they always seemed to shift their attention to the Dodo showing that we modify our perception of sound location depending upon what we see.
All in all, “Cirque de Perception” was one of the major attractions at the festival, even though the only music to be heard at this stall was Old McDonald. It even made it into the New Scientist Blog. Einstien’s Garden is managed and curated by Ellen Dowell, and sponsored by the Wellcome Trust as part of the Science at Play project.
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