One of my rules of thumb is: “Human heterogeneity is bigger than you think.”  At Less Wrong, Yvain explains it better than I ever have.  Lead-in:

There was a debate, in the late 1800s, about whether “imagination”
was simply a turn of phrase or a real phenomenon. That is, can people
actually create images in their minds which they see vividly, or do they
simply say “I saw it in my mind” as a metaphor for considering what it
looked like?

Upon hearing this, my response was “How the stars
was this actually a real debate? Of course we have mental imagery.
Anyone who doesn’t think we have mental imagery is either such a
fanatical Behaviorist that she doubts the evidence of her own senses, or
simply insane.” Unfortunately, the professor was able to parade a long
list of famous people who denied mental imagery, including some leading
scientists of the era. And this was all before Behaviorism even existed.

debate was resolved by Francis Galton, a fascinating man who among
other achievements invented eugenics, the “wisdom of crowds”, and
standard deviation. Galton gave people some very detailed surveys, and
found that some people did have mental imagery and others didn’t. The
ones who did had simply assumed everyone did, and the ones who didn’t
had simply assumed everyone didn’t, to the point of coming up with
absurd justifications for why they were lying or misunderstanding the
question. There was a wide spectrum of imaging ability, from about five
percent of people with perfect eidetic imagery to three percent of people completely unable to form mental images.

Dr. Berman [Yvain’s old prof] dubbed this the Typical Mind Fallacy: the human tendency
to believe that one’s own mental structure can be generalized to apply
to everyone else’s.

Yvain then expertly applies this point to diverse examples, including:

1. Personality clash:

I’m about as introverted a person as you’re ever likely to meet – anyone
more introverted than I am doesn’t communicate with anyone. All through
elementary and middle school, I suspected that the other children were
out to get me. They kept on grabbing me when I was busy with something
and trying to drag me off to do some rough activity with them and their
friends. When I protested, they counter-protested and told me I really
needed to stop whatever I was doing and come join them. I figured they
were bullies who were trying to annoy me, and found ways to hide from
them and scare them off.

Eventually I realized that it was a
double misunderstanding. They figured I must be like them, and the only
thing keeping me from playing their fun games was that I was too shy. I
figured they must be like me, and that the only reason they would
interrupt a person who was obviously busy reading was that they wanted
to annoy him.

2. Pedagogy:

There’s a lot of data on teaching methods that students enjoy and learn
from. I had some of these methods…inflicted…on me during my school
days, and I had no intention of abusing my own students in the same way.
And when I tried the sorts of really creative stuff I would have loved
as a student…it fell completely flat. What ended up working? Something
pretty close to the teaching methods I’d hated as a kid. Oh. Well. Now I
know why people use them so much. And here I’d gone through life
thinking my teachers were just inexplicably bad at what they did, never
figuring out that I was just the odd outlier who couldn’t be reached by
this sort of stuff.

3. “Game”:

There are a lot of not-particularly-complimentary things about women
that many men tend to believe. Some guys say that women will never have
romantic relationships with their actually-decent-people male friends
because they prefer alpha-male jerks who treat them poorly. Other guys
say women want to be lied to and tricked. I could go on, but I think
most of them are covered in that thread anyway.

The response I
hear from most of the women I know is that this is complete balderdash
and women aren’t like that at all. So what’s going on?

Well, I’m
afraid I kind of trust the seduction people. They’ve put a lot of work
into their “art” and at least according to their self-report are pretty
successful. And unhappy romantically frustrated nice guys everywhere
can’t be completely wrong.

My theory is that the women in this
case are committing a Typical Psyche Fallacy. The women I ask about this
are not even remotely close to being a representative sample of all
women. They’re the kind of women whom a shy and somewhat geeky guy knows
and talks about psychology with. Likewise, the type of women who
publish strong opinions about this on the Internet aren’t close to a
representative sample. They’re well-educated women who have strong
opinions about gender issues and post about them on blogs.

lest I sound chauvinistic, the same is certainly true of men. I hear a
lot of bad things said about men (especially with reference to what they
want romantically) that I wouldn’t dream of applying to myself, my
close friends, or to any man I know. But they’re so common and so
well-supported that I have excellent reason to believe they’re true.

You could say that if Yvain’s right, each of us inevitably lives in our own Bubble.  To be enlightened is to see the two layers of film that separate us from everyone else.