Reader interpretation vs author intention

Can anyone help me out with the name of the particular term... An audience seeing something that wasn't particularly what the writer intended to be there, but there it is... basically, once a piece is finished, the reader or audience has just as much say in the work as the creator. Having a conversation about it, talking about people like David Lynch, or the Nolan brothers choosing not to answer questions about Memento, and for the life of me I'm blanking on the name of the actual term.