We’ve all seen it happen – someone makes one mistake or bad decision, and suddenly they’re labeled as a “bad person.” Despite years of responsible behavior, they’re now viewed through a lens of suspicion and criticism.

For example, consider a long-time employee named John who has always arrived on time and helped colleagues. But one day John shows up late to an important meeting due to extenuating circumstances. Even though it’s the first time he’s been late, his boss assumes John is lazy and criticizes him harshly. From now on, his boss interprets even neutral actions negatively.

Why does this phenomenon persist, where a single negative action shadows the good? As it turns out, there are several psychological factors at play that reinforce our tendency to let one “bad” event overshadow numerous “good” ones when judging someone’s character.

The Negativity Bias: Hardwired to Focus on the Bad

It starts with our hardwired negativity bias. Human brains have evolved over millennia to pay more attention to negative or threatening information as a survival mechanism. Noticing potential dangers faster than opportunities helped early humans survive. But in modern society, this negativity bias means we zoom in on the bad parts of an experience over the good. Research shows we feel the sting of losses more than the joy of equal gains.

So when someone makes a mistake or does something wrong, our minds fixate on it compared to all the right they’ve done. Like with John, a single lateness after years of punctuality still provokes an outsized reaction. Our negativity bias highlights the one bad over the mountain of good.

The Fundamental Attribution Error: Judging Others Harshly

This tendency dovetails with the fundamental attribution error – humans’ pattern of believing negative actions reflect someone’s inherent character while letting ourselves off the hook by blaming situational factors for our own missteps. When we look at others, we attribute their mistakes to dispositional traits like laziness or recklessness. But when we slip up, we justify it as due to exterior forces, like unreasonable work demands.

So when we see others mess up, we think “they’re just a bad or incompetent person.” But when we make a mistake, we rationalize “I had no choice in that situation!” This attribution error causes us to judge the same actions much more harshly in others than ourselves.

Confirmation Bias: Seeking Information that Confirms our Views

Once we have a negative perception of someone, confirmation bias often kicks in. Confirmation bias is our tendency to selectively look for and remember information that fits our pre-existing views and ignore evidence that contradicts them.

For example, if John’s boss now sees him as irresponsible, she’ll notice when he takes a long lunch but overlook days he skips lunch to work. She’ll recall unreturned emails but forget quick replies. This biased searching reinforces her perception, entrenching negative judgments based on limited data.

The Role of Social Norms and Emotions

Beyond core psychology, social norms and emotions also play a role. Violating social expectations often incurs social disapproval, even if the action itself wasn’t unethical. Lateness violates workplace punctuality norms. And emotions like anger or disappointment can shape our perceptions of others when they don’t meet our standards, even for minor failings. We feel they should have done better.

Cognitive Dissonance: Restoring Internal Consistency

Cognitive dissonance also influences judgments about people after they slip up. Cognitive dissonance means the discomfort we feel from holding two contradictory beliefs or perceptions. For instance, if we previously thought highly of someone, a single subsequent bad action causes dissonance between that positive view and this new negative information.

To reduce discomfort, we subconsciously emphasize their mistake and flaws while downplaying past good impressions. This returns our perceptions to consistency. With John, his boss rationalizes away previous praise as misplaced to reconcile John’s sudden bad behavior with his overall positive view.

Factors like our negativity bias, attribution errors, confirmation bias, social norms, emotions, and cognitive dissonance collude to focus our overall judgment of someone on singular negative pieces of information. This overlooks people’s full humanity and complexity.

With awareness of our own innate biases, we can strive to take a more balanced, empathetic approach when evaluating others after they make a mistake. We should consider situational factors, remember past good actions, and weigh all data points objectively. A single bad choice in one instance shouldn’t define someone’s overall worth or cancel out their history of good deeds. Extending grace helps us build understanding and connection.