Trust is the psychological foundation of the human species. When it's there, we don't think much about it; it just works, as it has for millions of years. But when it's gone, the cracks begin to emerge and the once-strong structures of our relationships and society crumble.

Safe to say that at a societal level, the cracks are starting to show. There's a general skepticism in today's climate towards our societal and cultural institutions. The Edelman Trust Barometer shows that events of corporate malfeasance, government corruption, and fake news are upending the social contract and breaking trust en masse.

A feeling of general distrust in the air is bound to have an effect on our trustworthiness of others. It goes from "What can I trust?" to "Who can I trust?"

To trust or not to trust? 

At this point, you may want me to take this piece in the direction of: "This is how we can work together to regain trust within our institutions and with each other."

A lovely sentiment to be sure. But a bit Pollyanna-ish, don't you think? And the fact is, there are people out there who can't be trusted. In which case, you should be equipped with the right tools to figure out friend from foe. It helped our ancestors, it'll help you, too. 

In relationships, trust is implicated in two types of scenarios. First, and most obviously, is when someone does something explicit in their behavior to break your trust. They screw you over, throw you under the bus, get caught red-handed in a cheat or a lie. 

The second scenario is more interesting. These are the more covert scenarios that fly under the trust radar. You know, the ones where you have a "bad feeling" about a person for no particular reason. They haven't done anything to you. But the feeling persists. In these particular instances, deciding whether you can trust someone is less about "knowing" and more about "sensing."

Something's up...but what is it? 

The sensing is not a mystical, spidey-sense phenomenon, it's a brain computation. The human brain evolved what psychologists call a cheater detection system, a highly sensitive suite of psychological responses that allow us to unconsciously "know" when someone can't be trusted.

The system is constantly on the lookout for subtle cues during a social exchange that might betray a person's true intentions. When enough of these inputs trigger the system, the brain computes an evaluation, leaving you with that "sneaky feeling" that a person can't be trusted.

What are these subtle cues?

Recent research evidence is suggesting there are four nonverbal behaviors that, when done together, act as a reliable signal of untrustworthiness. According to the research, the four subtle behaviors are hand fidgeting, face touching, leaning away, and crossing arms.

What's key here is that not a single one of these in themselves is predictive of untrustworthiness. As the lead researcher, David DeSteno, comments, "If someone is leaning away, is it because they are distancing themselves from you, or does their back hurt? You can't really tell when it's one cue." But as the evidence suggests, the four cues in combination advertise untrustworthiness: The more often people perform these sets of actions, the less trustworthy their behavior was.

Until the utopian society of total trust is achieved, it would be wise of you to know these four subtle nonverbal cues. Be on the lookout for them the next time you get that "feeling" about someone. Just make sure the feeling isn't directed to you...and, whatever you do, avoid fidgeting with your hands, touching your face, leaning away, and crossing your arms.