Here’s an analysis by a Stanford professor on the recent New Hampshire primary:
Our analysis of all recent primaries in New Hampshire showed that there was always a big primacy effect — big-name, big-vote-getting candidates got 3 percent or more votes more when listed first on the ballot than when listed last.
The initial reaction might be that it’s yet another example of inept election management. And it is. But what’s scarier for me is that people would do this. Remember, this is a primary. There is (as far as I know) no other issue being discussed, so it’s just about the candidate you want. There’s no major moral imperative either – many people feel it’s their civic duty to vote in an election, even if they don’t like any of the candidates, but the same can’t be true to a significant degree in a primary. So presumaby these are motivated, interested people who want to make their voice heard. And they STILL get distracted by something as trivial as word order.