“3D Thinking” Page 22 The McGurk Effect: An example of how our brain forms perceptions from fragmentary sensory information. Here, from a BBC 2 program, Prof Lawrence Rosenblum pronounces the word “ba” continuously. The video shows his mouth pronouncing “ba” but then the video shows his mouth changing to pronounce the word “fa” – but the audio does not change. The effect is that our brain hears ‘fa” when the audio is still pronouncing “ba.” The effect was first discovered by Harry McGurk and John MacDonald at the University of Surrey.