Paul Budnik email@example.com
This is the oldest of the interpretations. It is based on Bohr's notion of `complementarity'. Bohr felt that the classical and quantum mechanical models were two complementary ways of dealing with physics both of which were necessary. Bohr felt that an experimental observation collapsed or ruptured (his term) the wave function to make its future evolution consistent with what we observe experimentally. Bohr understood that there was no precise way to define the exact point at which collapse occurred. Any attempt to do so would yield a different theory rather than an interpretation of the existing theory. Nonetheless he felt it was connected to conscious observation as this was the ultimate criterion by which we know a specific observation has occurred.
N. Bohr, The quantum postulate and recent the recent development of atomic theory, Nature, 121, 580-89 (1928), Reprinted in Quantum Theory and Measurement, p 87, (1983).