Better insight into human behavior and decision science by a county government official might have changed the course of world history.
The 2000 presidential election
Late in the evening of November 7, 2000, as projections from the U.S. presidential election rolled in, it became apparent that the outcome would turn on which candidate carried Florida. The state initially was called by several news outlets for Vice President Al Gore, on the basis of exit polls. But in a stunning development, that call was flipped in favor of Texas Governor George W. Bush as the actual ballots were tallied.1 The count proceeded through the early morning hours, resulting in a narrow margin of a few hundred votes for Bush that triggered an automatic machine recount. In the days that followed, intense attention focused on votes disallowed due to “hanging chads” on ballots that had not been properly punched. Weeks later, the U.S. Supreme Court halted a battle over the manual recount in a dramatic 5–4 decision. Bush would be certified the victor in Florida, and thus president-elect, by a mere 537 votes.
The “butterfly ballot”
Less attention was paid to a news item that emerged right after the election: A number of voters in Palm Beach County claimed that they might have mistakenly voted for conservative commentator Pat Buchanan when they had intended to vote for Gore. The format of the ballot, they said, had confused them. The Palm Beach County ballot was designed by Theresa LePore, the supervisor of elections, who was a registered Democrat. On the Palm Beach County “butterfly ballot,” candidate names appeared on facing pages, like butterfly wings, and votes were punched along a line between the pages (see Figure 1). LePore favored this format because it allowed for a larger print size that would be more readable to the county’s large proportion of elderly voters.2
Figure 1. Palm Beach County’s 2000 butterfly ballot for U.S. president
Ms. LePore unwittingly neglected an important behavioral principle long known to experimental psychologists: To minimize effort and mistakes, the response required (in this case, punching a hole in the center line) must be compatible with people’s perception of the relevant stimulus (in this case, the ballot layout).3,4 To illustrate this principle, consider a stove in which burners are aligned in a square but the burner controls are aligned in a straight line (see Figure 2, left panel). Most people have difficulty selecting the intended controls, and they make occasional errors. In contrast, if the controls are laid out in a square that mirrors the alignment of burners (see Figure 2, right panel), people tend to make fewer errors. In this case, the stimulus (the burner one wishes to light) better matches the response (the knob requiring turning).
Figure 2. Differences in compatibility between stove burners and controls
Confused voters may have cost Al Gore the presidency
A close inspection of the butterfly ballot reveals an obvious incompatibility. Because Americans read left to right, many people would have perceived Gore as the second candidate on the ballot. But punching the second hole (No. 4) registered a vote for Buchanan. Meanwhile, because George Bush’s name was listed at the top of the ballot and a vote for him required punching the top hole, no such incompatibility was in play, so no related errors should have occurred. Indeed, a careful analysis of the Florida vote in the 2000 presidential election shows that Buchanan received a much higher vote count than would be predicted from the votes for other candidates using well-established statistical models. In fact, the “overvote” for Buchanan in Palm Beach County (presumably, by intended Gore voters) was estimated to be at least 2,000 votes, roughly four times the vote gap between Bush and Gore in the official tally.5 In short, had Ms. LePore been aware of the psychology of stimulus–response compatibility, she presumably would have selected a less confusing ballot design. In that case, for better or worse, Al Gore would almost certainly have been elected America’s 43rd president.