America is experiencing a bizarre disconnect between real and perceived danger when it comes to kids. But why?

Why are we arresting moms for putting their kids in "danger" for doing the things our own moms did without anyone batting an eye, like letting us walk to school, or play outside, or wait at home a short while? Recall that just recently a mom was arrested for letting her kids, 8 and 9, wait at the condo for under an hour while she went to pick up dinner.

Well, a new study by researchers at the University of California-Irvine may have figured it out. "Our fears of leaving children alone have become systematically exaggerated in recent decades—not because the practice has become more dangerous, but because it has become socially unacceptable," as the university put it in a news release.

In other words, the only socially acceptable mom has become a mom who never takes her eyes off her kids. With that in mind, whenever we see an unsupervised child, we automatically assume the child has a bad mom. And once we are harshly judging that mom, our minds unconsciously judge her "crime" extra harshly, too. We believe it to be more dangerous than it actually is. So it's a feedback loop: unsupervised kids have terrible moms, terrible moms endanger their kids.

Remember that viral video of a man shrieking at a mother who let her child wait in the car a few minutes while she went into a phone store—a store with a plate glass window through which she could keep an eye on her kid? The videotaper was screaming as if the mom had thrown her child down a well. Many of the comments were just as vicious—"Shame on that horrible mother" was a mild one—even though the child was demonstrably fine.

But our perceptions have nothing to do with the world actually becoming more dangerous (crime is at a 50-year low), or even the legitimate fear of children getting overheated in a car (moms get yelled at for leaving their children for the few seconds it takes to return a grocery cart). Instead, our perceptions have everything to do with our seriously screwed up "moral intuition."

To test that notion, UC-Irvine researchers Ashley J. Thomas, P. Kyle Stanford, and Barbara Sarnecka asked 1200 people to rate how much danger kids were in on a scale of one to ten, in different situations. The only thing the researchers varied was the reason the kids were left unsupervised.

In one survey question, for instance, they presented the story of a child waiting 30 minutes in a car because her mom had been dropping off a book at the library but was hit by a car and temporarily knocked unconscious.

Other groups of survey takers were told the child was left in the car the same amount of time, but the reason for mom's absence was different: She was working, or volunteering, or relaxing, or off to see her lover.

While all five groups of respondents felt the child was in danger, the group that judged the danger the lowest was the group told that the mom was unconscious—in other words, that the mom did not intend to leave her child unattended, it was an accident.

The groups told that the mom was doing anything else—working, volunteering, relaxing—felt the child was in more danger, and the group told that the mom was having an affair felt the child was in the most danger.

So the perceived danger quotient went up when the respondents felt more judgmental toward the mom.

"People felt it was more immoral to leave a child voluntarily than involuntarily," Prof. Sarnecka, a developmental psychologist, told me in a phone interview (after thanking me for Free-Range Kids, the site that "made our research possible"). "And once you think only a bad mom would leave her kid in that situation, then your belief about how dangerous it is goes up."

When the researchers substituted dads for moms in these scenarios, the dads' work-related absences were treated the same as their unintentional absences: Their kids were perceived at the very lowest level of danger. But when women left their kids to do some work, the perceived danger increased.

Unconsciously we seem to consider moms as selfishly, immorally choosing to endanger their kids by going to work. Working mom = evil mom.

The dad test sample was small. The researchers intend to delve into it deeper the next time around. But even the results of the mom-only surveys seem to show that Americans believe the only decent way to raise a child is with a full-time mother never taking her eyes off her kids. Only June Cleaver types get a pass.

Anyone else—impoverished moms, single moms, moms with big families—are seen as putting their kids in danger simply because they cannot directly supervise every kid every second.

Since many moms do work, and since all moms make daily choices as to when to let the kids wait at home, or in the car, or get themselves home from soccer, this exaggerated idea of child endangerment has very real world consequences. Cops seeing kids at the park think the mom is negligent. Child Protective Services represenatives over-estimate the danger to latchkey kids. The result is arrested parents, and arrested development of the kids.

"People are very attached to the idea that they are rational beings," says Sarnecka. But as the study shows, they aren't. They are swayed by unconscious judgments. "It would be really great if people could be rational about their irrationality."

Until that happens, we cannot have open-ended laws that defer to an authority's spidey sense. Instead, we must insist that a child be in provable danger of immediate, indisputable, statistically likely and egregious harm before parents be judged negligent.

Because otherwise they'll just be judged, period—especially the moms, and especially the moms with fewer resources. And that harsh judgment will suffice for a verdict of guilty.