Whenever I see a poster or movie trailer touting 3-D, I think of that old sign they used to have outside businesses back when air conditioning was still a novelty: “Come in. It’s cool inside.”

I seem to recall that some of these signs were still around when I was growing up in the ’70s, but I have reached an age where I can’t differentiate between my own memories and scenes from movies I haven’t watched in a while.

Anyway, signs like these disappeared because touting air conditioning became as superfluous a pastime as touting air.

These days, it is no more surprising to find yourself breathing the first, as breathing the second.

That’s the way I feel about 3-D.

3-D is everywhere, and yet sonorous voiceover guys still seem to want me to get excited about it.

Last spring, I spoke with an executive in the movie exhibition business who told me that he thought technological innovations like 3-D and IMAX can make bad movies seem better. He (perhaps wisely) declined to cite examples.

I have tested out this theory on several films since then, and I can say with confidence that it doesn’t work on me or for me.

Take “Thor,” for example.

I won’t go so far as to say “Thor” is a bad film (because I am planning to go exactly that far later in the column). But 3-D adds nothing to it except $3 to the admission cost.

This has been true of every feature-length, live-action 3-D movie ever made, with the possible exception of “Avatar.”

Maybe part of the problem is that every filmmaker working today has been trained in 2-D filmmaking.

Will 3-D film schools crop up someday, just as Smell-O-Vision film schools popped up in the ’60s and Sensurround film schools in the ’70s?

Only time will tell.

For now, I think, 2-D filmmaking conventions will continue to hamper full realization of the creative possibilities of 3-D (whatever those may be).

When 3-D first became really popular in the ’50s, it was primarily used to poke things out of the screen at people. But modern life has too much poking in it.

Everybody feels over-poked, it seems to me. Some poor citizens are even awakened out of a sound sleep by poking.

So we expect more from our 3-D. And I am not sure we are getting it from the current version of the technology.

At present, most 3-D movies require more effort and suspension of irritability on the part of moviegoers than they should.

Now don’t get me wrong – I don’t think 3-D is a technological dead end.

Please don’t mistake me for one of those people who dismiss 3-D as a gimmick (despite my likening it to Smell-O-Vision and Sensurround). I think it is more than a gimmick but something less than a miracle.

A gimmiracle?

I believe 3-D will one day live up to its current overinflated billing. But some changes need to be made, and they may not be made quickly enough to appease people who are starting to wonder whether 3-D is really worth the extra bucks.

Even the most pep-filled cheerleader for this technology has to admit that 3-D movies are just darker than 2-D movies.

Many of my friends are abandoning the format after squinting their way through too many underlit 3-D blockbusters.

Last July, current “Batman” director Christopher Nolan said of 3-D, “On a technical level, it’s fascinating … but on an experiential level, I find the dimness of the image extremely alienating.”

Nolan is refusing to shoot the final film in his “Batman” trilogy, “The Dark Knight Rises,” in 3-D, which is a good thing when you consider that the first two films were among the darkest 2-D blockbusters ever made.

There is a science behind why 3-D films are darker than 2-D films involving units of light intensity called foot candles and foot lamberts.

Because the first one sounds to me like a medieval torture device and the second one like an Adam Lambert fan club consisting of foot fetishists, I had better not try to get too technical here.

Suffice it to say that more powerful 3-D projectors are on the way.

Until then, we’ll just have to be grateful that – for the most part – nothing is poking out at us.

Picks and pans

In theaters:

“Thor” (PG-13) – Some questions I have about “Thor” – Why does Asgard, the home of deities worshipped by people who wore animal skin and fur, look like a colossal Swiss timepiece floating in space? Why are there giant robots in Asgard? Why does Thor look like a lost member of the band Whitesnake?

Why is the sight of Thor being dragged through the air by his magical hammer so silly? Why did the filmmakers dispense with so much of the comic book’s much more interesting origin story, including amnesia and disability on the part of Thor’s alter ego? Is there a Norwegian style of martial arts that explains Thor’s fighting abilities? Why is this movie so rote and perfunctory? Actually, I already know the answer to that last one.