When President Trump chose to trust Putin over the United States' own intelligence agencies on live TV, it was arguably the most abnormal moment in a presidency rife with them.

Trump's statements in Helsinki have received swift and, so far, sustained condemnation. But the summit is just one in a series of Trump controversies that would have ended another presidency. And despite how shockingly and indisputably out of the norm Trump's comments were, the public may struggle to grasp their enormity and could soon move on, if history is any guide.

What's behind the collective tendency to normalize Trump's out-of-the-ordinary behavior and policies?

Blame your brain.

Our brains are really great at adapting to stimuli, both positive and negative.

The hedonic treadmill theory (usually used to conceptualize why happiness fades) suggests that there is no happy or tragic event that humans don't end up quickly adapting to.

Get a job that pays you five million dollars a week? You'll be happy for a bit, but soon the newness will become normal and you'll settle into a routine.

Lose a a job? Get broken up with? Yes, it hurts. But eventually, you adjust to the new normal.

The same thing happens when a sitting president tells blatant lies on a continual basis. It feels huge at first — remember the outrage over Trump's crowd sizes? — but after a while, it's just the order of the day. The disingenuous use of "alternative facts" and "fake news" becomes commonplace and banal while the stakes for outrage and action are raised even higher.

Here's a fun fact: Our brains don't let us be as smart as we think we are.

Hold up one second! I don't mean you're unintelligent. But the reality is that our brains are not objective arbiters of truth; they're always tricking us in order to make sense of reality.  

As humans, categorizing and making sense of things is essential to our survival, but research shows that we're not so great at making these kinds of discernments. Just think about how quickly you've seen people whose intellect you respect fall for "fake news" as long as it was coming from their camp.

The fact that our minds are intent on making things normal isn't inherently a bad thing. But it can be a huge problem when our politicians use it against us.

Normalcy is important for the human race's continuance — otherwise we'd be plagued with anxiety over every little change. But as the BBC pointed out, humans are "so protective over the concept of normal" that we sometimes allow complacency to take over, allowing even the most terrifying ideas to seem "not so bad" until it's too late.

In an article published by The New York Times shortly after Trump's inauguration, Yale psychologists Adam Bear and Joshua Knobe, who study normalization, wrote that people have a hard time separating "how things out to be" (ie, the ideal) from what's actually going on (the average), thereby blurring the two into "a single undifferentiated judgment of normality." This, they argued, allows Trump to commit more egregious actions with less blowback.

"Our research suggests, for example, that as President Trump continues to do things that once would have been regarded as outlandish, these actions are not simply coming to be regarded as more typical; they are coming to be seen as more normal," Bear and Knobe wrote. "As a result, they will come to be seen as less bad and hence less worthy of outrage."

Now more than ever, we can't let our brains trick us out of seeing reality.  

Perhaps rushing out into the street to scream "this isn't normal" every time the president does something disgraceful isn't the best course of action — who would get any work done? — but it's imperative that we don't allow it to happen without pushback. And that means being cognizant every time any elected official acts in bad faith and hopes to get away with it.

As Margaret Sullivan wrote in The Washington Post, Americans must see the press conference Trump and Putin gave as a "moment of truth," as well as a call to action.

Journalists have already started answering that call. When Sarah Huckabee Sanders refused to answer NBC reporter Hallie Jackson's questions at a July 18 press briefing, The Hill's Jordan Fabian yielded his time to her so she could follow up — and it's up to all of us to follow suit.

Trump's behavior has never been normal. It can't be treated as such any longer.