  Predecoherence, as its name indicates, is the same physical effect as
decoherence, originating in the same interactions with an environment,
injecting also incoherence and breaking unitarity. But whereas decoherence acts
immediately after a measurement, predecoherence is acting long before. It is
also a very strong effect and its main properties are established in this
paper, including generation, transport, damping, and stationary level. A
mechanism for objectification, or wave function collapse, is also proposed as
consisting in a perturbation by predecoherence of the intricacy between a
measuring system and a measured one. The theory is made explicit on a special
example and the quantitative results are found sensible.
