According to Efstratios Manousakis, a professor of condensed matter physics at Florida State University in Tallahassee, the key to consciousness could be lie in the quantum effects that occur in the brain when one is viewing ambiguous figures like the spinning silhouette (or Rubin’s vase or the Necker Cube).
These optical illusions are ambiguous because at any one instant they can be perceived either in one way, or in the other, but not in both. The image is said to “flip” when our perception changes from one interpretation of the image to the other. In the case of the spinning silhouette, some find it more difficult than others to switch between the two percepts.
Manousakis bases his model of consciousness on the assumption that conscious awareness is generated anew each time one flips an ambiguous figure. He believes that the ability to flip the image is akin to quantum superposition, in which both possible interpretations co-exist simultaneously in a state that can be expressed as a quantum wave function. Each time the image is viewed, the wave function collapses and one or the other interpretations is perceived.
Exactly what happens in the brain during the image flip could therefore be a neural correlate of consciousness, and may provide important clues to how the brain generates this most elusive of phenomena.
Manousakis therefore collated the data from studies in which participants had their brain activity measured with electroencephalongram and brain imaging while viewing ambiguous figures, and determined the firing rates of neurons before, during, and after they flipped the images. Using these figures, he then determined a firing pattern which he believes is characteristic of the quantum effects that underly consciousness.
Unlike some theories of quantum consciousness, such as that of Stuart Hameroff and Roger Penrose, this one is testable. Using data from studies in which participants were under the influence of LSD (which reduces the neuronal firing rate), Manousakis accurately predicted the frequency with which the subjects could flip the images.
Some researchers who have been critical of previous attempts to use quantum physics to explain consciousness therefore think Manousakis’s model is plausible.
Manousakis, E. (2007). Quantum theory, consciousness and temporal perception: Binocular rivalry. doi: 0709.4516. [Full text]