Jean Baptiste Buridan, a 14th-century French philosopher, popularized a thought experiment first attributed to Aristotle according to which a donkey that is precisely equidistant from two identical piles of hay will die of starvation, because “Buridan’s Ass” is unable to choose between the two equally attractive options.

Consumers confronted with two options that are equally attractive behave similarly. They find themselves unable to choose, unless, as scholars at Duke University demonstrated in 1982, a third option that is “dominated” by one of the other options — the “decoy” — is introduced into the choice set. Whether it be for beer, automobiles, television sets, health care, vacation spots, restaurants, job applicants or choosing a presidential candidate, adding a dominated alternative to a choice set results in an attraction toward the most similar dominant alternative. In other words, Buridan’s Ass would literally have his head turned if a small, relatively unattractive pile of hay appeared next to one of the original piles of hay.

Undecided voters are no different. Like consumers who might freeze when choosing between a beer that tastes great and another that is less filling, voters might freeze when choosing between two candidates who are equally attractive, but for different reasons.

One candidate — call him A — might have an attractive immigration policy but an unattractive health care policy, while the other — call him B — might have an attractive health care policy but an unattractive immigration policy. What’s a conscientious voter who cares about both immigration and health care to do?

As my colleagues and I have shown, choosing between equally (un)attractive options activates the amygdala, the seat of negative emotions. People get irritable when the choice is hard! Introducing a decoy makes the problem easier. So, if a new candidate appears and his immigration policy is slightly less attractive than A’s, but his health care policy is the same, candidate A’s attractiveness increases because he now dominates the new candidate. The new entrant acts as a dominated decoy, making candidate A look pretty darn good. Relative to the new candidate who now serves as a reference point, candidate A represents a gain.

Notice how the issue of health care has now taken a back seat. Because more candidates are talking about immigration policy, the importance of immigration policy as an evaluative dimension increases, as my colleagues and I have shown. The voter’s attention shifts to the options that are emphasizing similar issues — great immigration policy vs. pretty good immigration policy — and she finds it relatively easy to pick the superior option.

Now, imagine if 24 Democratic candidates are talking about a humane immigration policy. Or health care. Or income inequality. And, are arguing about it. Vehemently. Voters’ heads will turn. Attention toward these candidates will increase, and the issue they are arguing about will gain in importance. The attraction effect ought to help when a large number of candidates on one side are arguing about something, anything, because that conversation will suck the oxygen out of the room and lead to incessant media coverage.

The empirical evidence for the attraction effect is robust and substantial. Perhaps more important, the attraction effect might be one explanation for the success of the Republican presidential campaign in 2016. With 17 Republicans vs. five Democrats, there was no contest in terms of media coverage and the power of the attraction effect in shifting voters’ attention. The sheer volume and decibel level associated with the Republican primary drowned out the relatively quiet contest among the Democrats. In 2019 and 2020, the situation is likely to be reversed. To the extent that the 20 or so Democratic candidates are able to attract attention because of policy, rhetorical or stylistic disputes, they will benefit due to the attraction effect. Seemingly, there will be little contest for the Republican nomination, and if there is a contest between President Donald Trump and William Weld, the attention accorded that contest is likely to be minimal.

Of course, Trump’s personality might negate this effect if his rambunctious style were to offset the attention that the Democratic candidates are able to accomplish. Likewise, policy pronouncements on a trade war, anti-immigrant initiatives, a chimerical nuclear deal with North Korea or an incipient war with Iran will all diminish if not eliminate the positive impact of the attraction effect. Until then, undecided voters might have their heads turned by a crowded Democratic field.


Akshay R. Rao holds the General Mills Chair in Marketing at the University of Minnesota’s Carlson School of Management. He is at