Consciousness causes collapse is a problematic interpretation of quantum mechanics based on the idea that conscious observers should be treated differently than other objects. Here collapse means wavefunction collapse.
The process of "measurement" in quantum mechanics is interpreted as consciousness itself. It is not explained by this interpretation which animals and other beings already have consciousness, that is the right to collapse the wave function, and which do not. Because of the spiritual accent, this interpretation is rejected by most physicists but was argued in particular by Hungarian physicist Eugene Wigner.
This was also the main plot point of the novel Quarantine by Greg Egan.