source: http://en.wikipedia.org/wiki/Quantum_mind%E2%80%93body_problem

Quantum mechanics

The introduction of quantum mechanics substantially changed the status of the observer and measurements. The measurement problem studies how a classical observer can exist in a quantum world. The quantum world describes superpositions of very different states, but our perception is that of “classical” states in the macroscopic world, that is, a comparatively small subset of the states allowed by the quantum-mechanical superposition principle, having only a few, but determinate and robust, properties, such as position, momentum, etc. The question of why and how our experience of a “classical” world emerges from quantum mechanics thus lies at the heart of the foundational problems of quantum theory.
The determinism and materialism of classical mechanics, divorced or at least distanced science from many pre-scientific philosophies that held various dualist perspectives towards the mind. Some scientists (like Wigner) believe that quantum mechanics makes certain dualist ideas about the mind/body problem acceptable again within mainstream science, while others^[16] think there is little to gain from science entertaining those possibilities further (as described in the criticism section below).

Consciousness causes collapse

In his 1932 book The Mathematical Foundations of Quantum Mechanics, John von Neumann argued that the mathematics of quantum mechanics allows for the collapse of the wave function to be placed at any position in the causal chain from the measurement device to the "subjective perception" of the human observer. In 1939, F. London and E. Bauer argued for the latter boundary (consciousness).^[29] In the 1960's, Eugene Wigner reformulated the "Schrödinger's cat" thought experiment as "Wigner's friend" and proposed that the consciousness of an observer is the demarcation line which precipitates collapse of the wave function, independent of any realist interpretation. See Consciousness and measurement. Very technically, the Wigner identified the non-linear probabilistic projection transformation which occurs during measurement with the selection of a definite state by a mind from the different possibilities which it could have in a quantum mechanical superposition. Thus, the non-physical mind is postulated to be the only true measurement apparatus.^[16]

Quantum entanglement and the Power of Intention