Managua, Nicaragua – Daniel Ortega, the former Nicaraguan Sandinista leader, is back. Today he has a 31-percent approval rating, very close to what he needs to win the presidential election in November.

Well-meaning colleagues have advised me not to write about politics, as I am a behavioral scientist, not politician or a pundit. But I know well how behavioral science applies to politics: Tell people exactly what they want to hear enough times, and they will start to believe it.

Today there are enormous billboards for Ortega all over Managua. Brightly colored blue and pink, they are impossible to ignore. There is not much on these billboards; just Daniel’s head, the acronym “FSLN,” and one short, precise, universally appealing message on each: “A Triumphant Nicaragua, Guaranteed”; “Friends All Over the World”; “Education For All Children”; “Peace and Prosperity”; “Zero Hungry.”

My ride to work is six miles long. It is far from the most congested part of the city. Number of Ortega posters? 26. Number of competitors’ posters? 4.

According to Central Bank data in Nicaragua and World Bank indicators, what Ortega is saying he will do for Nicaragua is the opposite of what he did do during the 19 years he and his party were in power. GDP dropped precipitously, while inflation sky rocketed (i.e., there was little to be bought, and that little still couldn’t be afforded). There was no foreign investment. Most people went hungry.

Nevertheless, recently when I overheard the name Ortega, something popped into my mind — automatically and entirely unbidden: “Food for all.”

Thanks to the pressures of natural selection, humans have many cognitive mechanisms built in that allow us to quickly adapt to change. One of them is the ability to learn quickly. According to the law of association by contiguity — first hashed out by Aristotle and then refined by Ivan Pavlov and John Watson in the 20th century — if a person repeatedly experiences two environmental events at the same time (for example, a picture of Daniel Ortega’s head and the words “food for all”) these events will subsequently become associated in the person’s mind. The thought of one will elicit the thought of the other. Food for all? Daniel Ortega. Daniel Ortega? Food for all. This conditioning happens without us being consciously aware of it.

Advertisers have capitalized famously on our tendency to learn by association. Why else is beer invariably paired with half-naked people having a great time?

But just because we learn to associate two things with each other doesn’t mean we have to believe them, right? Wrong. Benedict Spinoza, the great 17th-century philosopher, may have been the first to understand that comprehension (understanding what a message is) and belief (accepting it as true) are two words for the same mental operation. While people are certainly capable of rejecting what they read, prior to doing so — that is, before they look for disconfirming evidence — they believe it. The nature of mental representation is such that we can change our minds after we have read something, but we cannot stop our minds from being changed by what we read. Acceptance of information we are exposed to is a passive and inevitable act. Rejection takes more effort — it is an active, conscious operation. This is why an enormous body of laboratory evidence shows us that repeated exposure to assertions for which there is no evidence increases the likelihood over time that people will believe these assertions. It’s why research on human lie detection has consistently uncovered a truthfulness bias — that is, people tend to conclude that a liar is telling the truth.

I have asked government insiders why there are so few billboards for right-wing candidates like Eduardo Monteleagre — the Liberal/Conservative Alliance candidate who has the blessing of Washington? Or for Jose Rizo — the Constitutional Liberal party candidate? Part of the problem is money, the other part the misguided assumption that billboards are irrelevant. But billboards are important. Any vehicle that allows for the repeated pairing of two unrelated things (Ortega and, say, prosperity) and that clearly communicates a concise message is important. We cannot help but be influenced.

The evolutionary message is clear: As a byproduct of our past, humans adapt and learn by association, and we tend to believe what we learn. If I have a warm, fuzzy feeling and an image of smiling kids sleeping well at night when I hear the name of Ortega, it is happening to other people too.

Nicaragua — after taking a serious economic hit during the Sandinista era — is finally recovering. Under democratic governance, GDP per capita is steadily increasing; debt, inflation and interest rates are dropping. Exports and foreign investments are on the rise. Pizza Hut just opened up down the street from my house. My nanny left because she got a better job at a new call center. The barrio in my backyard now has an Internet café.

Candidates need to brush up on their psychology. We shouldn’t let Daniel Ortega’s A in Psychology 101 stand in the way of continuing democracy, freedom, and progress in this beautiful country. – Susan Clancy is a psychology associate at Harvard University who is currently a professor in the department of consumer behavior at the INCAE business school in Managua, Nicaragua.