When ‘Oumuamua, a mysterious interstellar object, swept through our solar system last October, it elicited breathless news stories all asking the obvious question—is it a spaceship? There were no signs it was—although many people seemed to hope otherwise.

Throughout history most strange new cosmic phenomena have made us wonder: Could this be it, the moment we first face alien life? The expectation isn’t necessarily outlandish—many scientists can and do make elaborate, evidence-based arguments that we will eventually discover life beyond the bounds of our planet. To true believers, what may be more uncertain is whether or not such news would cause global panic—which depends on how our minds, so greatly influenced by our Earthly environment and society, would perceive the potential threat of something utterly outside our familiar context.

“There’s this feeling amongst the public—a very large fraction of the public—that the discovery of intelligent life at least would be kept secret by the government because otherwise everybody would just go bonkers,” says Seth Shostak, an astronomer at the SETI Institute who was not involved with the study. Perhaps it might make sense for our brains—tuned by millions of years of evolution to be wary of predators—to freak out over immensely powerful alien beings arriving on our cosmic doorstep from parts unknown.

But let’s say the situation hasn’t gone full “alien invasion” yet and malevolent starships aren’t sailing toward Earth, but rather we have read news of a definitive discovery of extraterrestrial life. How might we react then? Psychologists at Arizona State University (A.S.U.) used language-analyzing software to gauge feelings associated with 15 news articles about past discoveries that could have potentially been attributed to extraterrestrial life—reports covering items such as newfound Earth-like planets, mysterious astrophysical phenomena and possible life found on Mars. The articles used more positive and reward-oriented words than negative and risk-oriented ones, they report in a study published in January in Frontiers in Psychology. Although not in the paper, the team later similarly found articles about ‘Oumuamua skewed positive. They will report those results on Saturday in Austin, Texas, at the annual meeting of the American Association for the Advancement of Science.

“I think we’re generally sort of positively predisposed to novelty, unless we have strong reason to suspect it could harm us,” says Michael Varnum, a psychologist at A.S.U. Tempe and the study’s senior author. “Of course, I’m not saying that if we got news that there were a bunch of large alien warships on their way towards Earth that we would be happy about it.”

Martian Microbes

According to Varnum (and many astrobiologists), because simple, single-cellular life is presumably more cosmically common than star-crossing civilizations, it’s much more likely we will someday discover alien microbes rather than anything we could talk to. For his next set of experiments, he polled some 500 U.S. participants online to write about how they—and society in general—would react to news of such a discovery. Then he asked a separate group of around 250 people to read and respond to an actual New York Times article from 1996 that reported the potential discovery of fossilized microbes in a Martian meteorite. He compared this first batch of responses with those from another group of 250 people who read a 2010 New York Times article about the first synthetic life form created in a lab. He presented both stories without a dateline as if they were “fresh” off the press (although some participants likely realized they were not).

After analyzing the emotional tenor of their responses, the team found the participants generally used more positive than negative words when describing both extraterrestrial and synthetic life. This positive-to-negative word ratio was greater when participants were responding to the discovery of extraterrestrial life compared with the creation of synthetic life, which could be an indication the data wasn’t skewed by, say, a possible human tendency to write or react positively.

Participants tended to report they would respond more positively than society at large. Varnum thinks this could be because of a psychological tendency called “illusory superiority” in which a person thinks they have better qualities than others.

But Shostak notes the methodology of the experiment might have biased readers toward a more positive response. Even if it didn’t, “I can’t say [the conclusion] was a big surprise to me,” he says. “If we were to announce tomorrow we found microbes on Mars, people would not start rioting in the streets…but I don’t think anybody thought they were going to riot in the streets.” If Martians landed in Silicon Valley, however, “I’d buy a lot of frozen pizzas and head for the hills—I mean, I’d be out of here, too,” he adds.

The Ambiguous Alien

If it’s a discovery somewhere in between the extremes of an extraterrestrial microbe and rapacious, hostile aliens laying siege to Earth, will people respond differently based on the era or society they live in?

Our brains are wired with ancient circuits to defend us against predators. But as we navigate through the world, experience can also shape what we come to accept or to fear and how open we are to novelty. This study only looked at U.S. responses but two neuroscientists think the results might have been very different around the world. “If you look at societies that are much less open and much more xenophobic and so on, they might perceive [finding extraterrestrial life] as much more negative and unsettling,” says Israel Liberzon, a professor of psychiatry, psychology and neuroscience at the University of Michigan who was not part of the study.

“Culture may be a strong determinant of how we respond to novelty,” says Cornelius Gross, a neuroscientist at the European Molecular Biology Laboratory–Rome who studies the neural circuitry of fear and was also not involved with the research. “People came to America because they were novelty seekers, so we’ve selected for [that] and then continued to foster novelty seeking and place it very high on our list.” Furthermore, Shostak says, a person’s religious beliefs could play a powerful role in shaping their reaction to learning that humanity is in fact not as universally special as many traditions hold.

How we respond to such a situation can even be influenced by something as small as which extraterrestrial invasion movies people have seen or science fiction books they have read. If you see a lot of “UFO-type movies and the aliens are always ‘good’ in the end usually, then you might think that that stuff’s going to affect your [brain’s] prefrontal cortex,” Gross says. “And you’re going to adjust your responses to future novel [experiences].”

But all in all, Liberzon notes, context is key. Individually or collectively, human beings will respond very differently to observing a lion at a zoo versus coming across one in the African savanna, just as we would when reading about an alien in a science fiction novel versus actually meeting one.

And if scientists discover something so out of this world, literally, but also in the sense that we can’t compare it with anything we know, it seems futile, even silly, to make predictions about how humanity would react. Gross thinks we would probably first try to understand it, a reaction that can be interpreted as yet another ancient, evolutionarily sculpted defense system aimed at gaining control of a novel situation. There would probably be some positive responses and some negative ones, but they will all be “based on humans’ need to control their environment and make sure things are not threatening to them,” he says.

“When we think about what forms life may take elsewhere, we’re really limited by the fact that we only know about what life has evolved to look like here,” Varnum says. But “my suspicion is in fact, the sort of stranger it is, the more excited people would be.”