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The famous Wigner's friend experiment considers an observer -- the friend --and a superobserver -- Wigner -- who treats the friend as a quantum system andher interaction with other quantum systems as unitary dynamics. This is at oddswith the friend describing this interaction via collapse dynamics, if sheinteracts with the quantum system in a way that she would consider ameasurement. These different descriptions constitute the Wigner's friendparadox. Extended Wigner's friend experiments combine the original thoughtexperiment with non-locality setups. This allows for deriving localfriendliness inequalities, similar to Bell's theorem, which can be violated forcertain extended Wigner's friend scenarios. A Wigner's friend paradox and theviolation of local friendliness inequalities require that no classical recordexists, which reveals the result the friend observed during her measurement.Otherwise Wigner agrees with his friend's description and no local friendlinessinequality can be violated. In this article, I introduce classicalcommunication between Wigner and his friend and discuss its effects on thesimple as well as extended Wigner's friend experiments. By controlling theproperties of a (quasi) classical communication channel between Wigner and thefriend one can regulate how much outcome information about the friend'smeasurement is revealed. This gives a smooth transition between the paradoxicaldescription and the possibility of violating local friendliness inequalities,on the one hand, and the effectively collapsed case, on the other hand.

Classical information and collapse in Wigner's friend setups