Ask people what they’re scared of, and they’ll almost never mention anything you can’t see: clowns, snakes, clowns, heights, spiders, clowns, oh God clowns. But the invisible fears, the specters that light fires of self-doubt and make us question existence itself, never get any mention. Death, failure, disappointment — these bubble up when a lot is at stake, and as research is finding, for a reason known as “approach avoidance.”

Distant deadlines approach. Soft plans harden. Shadowy figures approach from the doorway. (Well, not so much the third one, but you get the point.) As we move forward through time, things come into view, both literally and figuratively. The trouble is that our ancient, accident-prone brains don’t have a mechanism for separating one from the other.

University of Chicago researchers have found in a recent study that so-called approach avoidance explains why we dread those deadlines, avoid those plans, and shrink at shadowy figures. Back in the day, when saber-toothed tigers were real threats, not some stuffed relic in a museum, watching out for oncoming hazards offered a real, vital benefit. Science also suggests this may be why we enjoy a nice view; finding high ground and seeing far distances means predators can’t surprise us. Like our appendix and tonsils, however, this fear has outlasted its usefulness.

“In life, we encounter not only spatially moving objects but also temporally and probabilistically moving events,” the researchers wrote. In other words, the target at a gun range may move toward and away from you. But in another sense, from the time you decided to make plans to visit the gun range and then set a date, the plans were approaching certainty and the event began moving toward you in time. After eight separate but related experiments to test this idea, the Chicago team found that, as it turns out, we humans hate this.

The eight tests graduated from simple tests of English letters moving toward participants, to emoticons, to actual images of people. In each case, the team found a stimulus moving toward participants yielded a “negative hedonic reaction” — or fear, to you and me. In the fourth experiment, however, when they moved the participant closer to the stimulus, just about no one felt a negative reaction. The approach avoidance disappeared, signaling something critical about being approached. In a temporal sense, too, subjects reported more negative feelings about a poster when more time had passed, regardless of whether it was positioned nearby or far away.

Perhaps the deepest insight came in the team’s final experiment. They presented subjects with the backstory of a cousin coming to visit. Each subject learned the cousin would arrive based solely on the availability of airline tickets, before being shown a timeline stating the intended arrival date. In two different conditions controlling for the probability the cousin would arrive, along with the specific date, the team discovered people reacted negatively no matter which way the team sliced it. The eight results showed the same thread of truth: People fear that which approaches them.

What are we to do about these fears? One instinct may be to silence them. Unfortunately, modern relaxation techniques will be of little help, as millions of years of evolution aren’t wiped out by a Sunday at the day spa. Perhaps the greatest defense against approach avoidance is understanding it even exists, and a great deal of exposure therapy research suggests that, indeed, avoiding avoidance — that is, confronting it — could be what allows us to stop feeling anxious whenever a friend asks to make plans or a wedding is around the corner. (Shadowy figures, however, should still give us cause for concern.)

Also, the researchers recognize the careful balance between overall feelings and feelings toward a stimulus. The research suggests even smiling faces can creep us out when they approach us, but that doesn’t mean we aren’t overjoyed to pick family up from the airport. In the moment, we may have a twinge of discomfort, but that moment soon passes. In other words, we shouldn’t let our hardwiring rules our lives. Who says a little fear isn’t healthy, anyway?

Source: Hsee C, Tu Y, Lu Z, Ruan B. Approach Aversion: Negative Hedonic Reactions Toward Approaching Stimuli. Journal of Personality and Social Psychology. 2014.