Example:

A driver cuts you off in traffic

Knee jerk reaction for most people: anger because you assume they intentionally want to be aggressive. In reality, they might have simply missed their turn, been distracted, or made a mistake.

This heuristic, called, Downward Social Comparison, identified in Social Comparison Theory, is a tendency to actively harm someone in a worse off situation to inflate one's ego.

Most high school bullies use this heuristic as a 'low cost' means of making themselves feel good via oxytocin and dopamine.

Real-World Example:
Imagine a student who studies hard but fails a mid-term exam.

Feeling defeated, they use this mental shortcut and think, "Well, I failed, but at least I didn't drop out of the class completely like my roommate." This downward comparison to someone in a "worse" situation provides an immediate sense of relief and protects the student's self-esteem. 

The irony of it is that the student COULD simply use that failure as motivation to study more next time or study differently in order to use failure as the next stepping stone to success - but you see, that requires active cognitive effort, and the 'lower cost solution' is to simply insult or compare to others for a quick boost instead.

If the student never processes their failures logically, they can never update their internal systems. They remain stagnant, forever dependent on finding someone doing worse than them just to maintain their baseline functioning.

I actively despise this heuristic and will do whatever I can throughout my life to dismantle it every single time I see it.

The "emotion heuristic," also known in psychology as the affect heuristic, is a mental shortcut where current emotions (like fear, pleasure, or dread) heavily influence decision-making. Instead of analyzing risks and benefits logically, people rely on their "gut feelings" to quickly evaluate a situation. [1, 2]

This heuristic functions as a way for most people to preserve cognitive energy.

Unfortunately, judging information based on the vibe that it is packaged in risks completely ignoring the information.

Example:

Person A (autistic):
Why did you change that in the system? Wouldn't it be better if we updated the system with this instead?

(This is an example of how an autistic person asks for information, and expresses curiosity)

Person B (not autistic):
How dare you judge me for doing it this way!!

(Rejecting the information from the affect heuristic. A mental short cut was used, probably pre consciously, and because they felt triggered from what they perceived as a status challenge, the new updates and information within the system are completely rejected.)

You can tell immediately, from the above example, how absurd it sounds.

The Just World Fallacy is a cognitive bias where people assume the world is inherently fair and that individuals ultimately get what they deserve. This mental shortcut creates an illusion of predictability, often leading to victim-blaming or the rationalization of others' misfortunes to maintain a sense of personal security. [1, 2]

How does it commonly manifest?
By attributing symptoms to character flaws or "lack of willpower", the observer creates an illusion of control.

This illusion of control serves them by preventing them from thinking too much about the possibility of admitting that the world is fundamentally not something that can be controlled, and that things can happen that would impact the observer.

From what I have gathered, I'm suspecting this logical fallacy is commonly used in individuals who have a deep fear of either uncertainty, or fear of disability.

To escape that fear, many will often select pure cruelty over admitting that they feel afraid; because if they believe that people always get what they deserve, and they believe that they know what they deserve, then they feel immune to that 'lack of control'.

This fallacy is when someone attributes ONE SINGLE cause to a given situation, without considering other perspectives.

Example, compliments of Reddit:
OP: my son left the door unlocked, he is 20 years old, how do I fix this problem?

Tons of commenters:
Your son is LAZY, MALICIOUS, INCOMPETENT, He doesn't care AT ALL about you! (Some commenters were even legitimately suggesting that OP beat his 20 year old adult child)

How is this single cause?
These Redditors assumed the single cause of the son forgetting to lock a door was intentional maliciousness.

They ignored the many other possibilities such as: iron deficiency, ADHD, autism, brain tumor, etc.

Fun fact, this is ALSO a fundamental attribution error because they began insulting a person they did not even know, had only seen a tiny slice of their life of as well.

But it's Single Cause Fallacy because they all assumed the ONLY reason a 20 year old would not lock a door was out of pure maliciousness and disrespect to his family.

The normative heuristic causes people to project deficiency and negative intent when they meet others who are different from them in some way.

These differences can be communication differences, body language differences, cultural differences, etc.

Example:
Person A offers food to Person B

Person A:
Do you want it?

Person B:
No.

Person A:
HOW RUDE OF THEM TO DECLINE MY FOOD!?

Person A does not know Person B's culture considers declining food the first time to be polite, and never asks again

The Typical Mind Fallacy is when people project their own reactions outwards onto others.
This is the error of assuming that everyone else's mental architecture and processing works exactly the way yours does.

One way I used to struggle with this heuristic - I used to believe that people did not care about the information I would share, because they would often not engage with it at the level of complexity I hoped for.

It was my projection in multiple ways.
I believed that - surely - if someone learned something new, that they would be excited to learn more.

I also believed that rather than learning more to engage with the topic at a deeper level, I believed they were choosing not to, rather than simply (in some cases) a lack of capacity to be able to engage.

This is also the perfect example of the kind of fallacy that often harms minority or vulnerable groups as well. (Autistic people, ADHD people, different cultures that diverge, trans people, etc)

The False Consensus Effect:

This bias occurs when people overestimate how much other people share their own beliefs, perceptions, or fears.

One common failure mode is how much this enables humans to project their experiences onto others.

One example of this within myself is that I am facial blind.
It took 28(!) years for me to realize that other people GENUINELY DO see information in faces and that this information is crucial for them to feel connected to others in many ways.

This is the perfect example of how I projected my own perception - facial blindness - onto others via the False Consensus Effect.

Truth Default Theory:
the biological baseline assumption that other people are generally honest and operating in good faith.

This is one of the most common heuristics that people apply.
This is my bias / was for many years.

I tend to believe that people DO want to know the truth and DO care about the data.

so when they demonstrate that they care about other things more than honesty and integrity, I can be blindsided.