The actor-observer bias is a term in social psychology that refers to a tendency to attribute one's own actions to external causes, while attributing other people's behaviors to internal causes. Essentially, people tend to make different attributions depending upon whether they are the actor or the observer in a situation.

The actor-observer bias tends to be more pronounced in situations where the outcomes are negative.

For example, in a situation where a person experiences something negative, the individual will often blame the situation or circumstances. When something negative happens to another person, people will often blame the individual for their personal choices, behaviors and actions.

SOURCE

ACTOR:
I cut off a woman in traffic.  I justify that I thought there was room, that I meant no harm, "my bad."  Sorry.

OBSERVER:
A woman cuts me off in traffic.  "Jesus Christ! [lays on the horn; notices "Trump" bumper sticker] Fucking Trump loving bitch!" It's obvious she was actively trying to cut me off because she somehow knew I support Sanders.

Everyone does this.  It's a part of the pathology of self-centeredness and personal movie-making that tells our brains that we are righteous and everyone else is only righteous when they agree with us.  It is the source of most of the hypocrisy inherent in the species.

Imagine that your class is getting ready to take a big test. You fail to observe your own study behaviors (or lack thereof) leading up to the exam, but focus on situational variables that affected your performance on the test.

The room was hot and stuffy, your pencil kept breaking, and the student next to you kept making distracting noises all throughout the test. When you get your results back and realize you did poorly, you blame those external distractions for your poor performance instead of acknowledging your poor study habits prior to the test.

One of your friends also did quite poorly, but you immediately consider how he often skips class, never reads his textbook, and never takes notes. Now that you are the observer, the attributions you make shift to focus on internal characteristics instead of the same situational variables that you feel contributed to your own substandard test score.

SOURCE

When you take a good hard look at the many poor in our country, you see this at play in a big way.  The poor whites are prone to having lots of babies (because there isn't much else to do when you're unemployed but fuck, so why not?), take little to no consideration for dressing "up," rely heavily on social services, welfare assistance, and LINK cards, and tend to gravitate toward casual law breaking (drugs, petty theft, assault).  

These poor whites justify why they are in these straits - it isn't their fault, the bank foreclosed on their home, they have no decent choices in a society that has such financial inequity.  But when asked about the poor black family next door, the black family just makes babies, wears their pants around their asses, are sponging off of the taxpayers' dollar, and are predisposed to criminal behavior.

Actor-Observer Asymmetry, man.

Liberals will berate Conservatives for denying science in the cases of Climate Change but justify their denial of science that holds Genetical Modified foods as essentially nothing more than food.

PoC will rage on about being grouped and stereotyped yet think nothing of painting anyone white as an active part of White Supremacy.

Misogynists cry out "No Fair!" when confronted with Misandrists.

One would think that one of each set was right but one would be sorely disappointed.  Numerous follow-up studies indicate that almost every time, both sides are wrong because each is so heavily biased that we all tend to distort the facts of any given conflict to fit our own respective narratives.  It's why Swimmer McRapistfuck's dad can, without a hint of irony, claim his rapist son is not really a rapist and the Rape-Apologist judge can agree with him.  If his wife were found being raped behind a dumpster in an alley, I'm pretty sure the bias would flip on its head.

We all determine that whenever there is conflict present in our lives, we deserve the benefit of the doubt and the Other deserves more severe punishment.  Because we are all pretty much a bunch of assholes.

Science proves it.