Suppose UK voters accept the Alternative Vote in the May referendum… but then don’t use AV to signal multiple party preferences?

Most of the discussion of the AV referendum assumes that if UK voters endorse changing the voting system, they will be eager to vote 1, 2 3, 4 etc to express support for several or multiple parties. But Colin Rallings and Michael Thrasher have their doubts. Reviewing the evidence from Queensland, which uses the same system as the proposed UK alternative vote, they believe that many voters will treat an AV election as just like ‘first past the post’, and not cast (or perhaps over time stop casting) multiple preferences.