Sunshine Hillygus and Todd Shields just came out with a book, “The Persuadable Voter: Wedge Issues in Presidential Campaigns,” where they argue that “persuadable voters are not a homogeneous group of unsophisticated and indifferent policy moderates, as has often been believed. Rather, persuadable voters hold diverse policy preferences, making it less clear which candidate offers a better match.” Hilligus and Shields point out that many many voters disagree with their party lines on important issues (see also my paper with Delia on this topic; correlations between party identification and individual issue attitudes have increased over the past few decades but are still only about 0.3 on a -1 to 1 scale).
The discussion of campaigns trying to exploit voters’ cross-pressure reminds me of Dave Krantz’s research on how people process information. Suppose you are evaluating hypotheses A and B, exactly one of which is true (for example, the suspect committed the crime or did not). You can imagine four kinds of evidence: (1) evidence supporting A, (2) evidence making A less likely, (3) evidence supporting B, and (4) evidence making B less likely. Dave et al. did some lab experiments manipulating these conditions, and found that people treat them differently: for example, people react differently if you give them evidence of the form (1)+(2), (1)+(3), or (2)+(4). Hillygus and Shields’s work focuses this idea by considering an area–political campaigns–where there is a lot of effort being made on both sides to persuade people. Their recommendation to the news media is to look beyond broadcast ads and speeches, to monitor microtargeted messages and direct mail, to make it more difficult for a political campaign to send different messages to different audiences.