The major party candidates have been campaigning for almost two years. Their competition has dominated print and electronic news coverage for most of that period. C-Span has broadcast coverage of entire political rallies and stump speeches. The candidates have appeared in presidential-primary and post-primary debates too numerous to remember their number. Their positions on the issues are detailed on their Web-sites and have been debated in countless blogs, editorials, op-eds, and TV punditry. Their party-affiliations and general political philosophies are well-known. The stories of the lives of the candidates have been much advertised and discussed, and most reasonably informed people can easily distinguish between truth and fiction in these stories. Despite third-party candidates like Barr and Nader, only one of the two major-party candidates will be elected: McCain or Obama. At this stage in the campaign season (if not long before), it doesn’t take the political equivalent of rocket science to choose or to have already chosen one of the two – even if you are not entirely satisfied with either. Undecideds are the reason that U.S. presidential elections cost hundreds of millions of dollars and last for two years. Why can’t they decide?

The satirically humorous answer from comedians Jon Stewart and John Oliver is that 55 percent of the undecideds are “racist Democrats,” “attention seekers,” and the “chronically insecure,” while 45 percent are “the stupid people,” a category that includes “numbskulls,” “nitwits,” and “Cubs fans” – among other groups.

Maybe Stewart and Oliver are on to something, but historians and other professionals can’t go around calling people racists, numbskulls, and nitwits, so we use terms like “inattentive voters” or “low-information voters” to distinguish some voters from others; namely, the “attentive” and “high-information” voters. Thus, the undecideds may just be those people who haven’t been paying much attention to the campaign or haven’t been giving much thought to it – they are neither engaged nor well-informed. This explanation, however, is not entirely satisfactory because we know that there are many among the “decideds” who are not much engaged or well-informed either. I’ve run into a lot of them while canvassing during this election cycle.

No doubt there are many other explanations for the undecided phenomenon, and I believe that one of them is cognitive; that is, the reason has to do with the mental processes of knowing and judging. In other words, there are lots of people who have trouble making up their minds about anything. Maybe this is a symptom of a psychological disorder or condition. But whatever it is and however respectful we may be about this condition, it remains an annoying fact of political campaigns.
Also see, "Why Are Undecided Voters Still Undecided? – Research Addendum."