Non-pros assume that the best picture Oscar goes to the pic voters believe to be the year’s creative high point, the very pinnacle of filmmaking achievement. Many voters themselves say that’s indeed what they’re thinking as they mark the ballot.

But what if the truth is more complex? What if something else is going on in the Academy members’ minds as they pick one nominee out of five?

Award watchers think they’ve identified that “something else,” which might be called the “Cachet Factor” — the idea that some 5,800 Academy members, voting as individuals but thinking as a group, are drawn to the one pic whose gravitas best represents the industry at large — or at least what the voters want their industry to be.

That doesn’t mean Academy members don’t vote for films that they like. The Cachet Factor helps explain why they like what they like.

Says critic Leonard Maltin about the top trophy: “The voters feel it has such weight — and it does — that it ought to be given to a picture with weight. Which explains 1982, when ‘Gandhi’ beat ‘E.T.’ ”

The Factor clears up 2005 as well. Polemic “Crash” came with helmer Paul Haggis’ avowed purpose to wield a “Brechtian hammer” and confront social realities. “Brokeback Mountain” was a realistic story whose subject matter conservative-minded voters chose to see as objectionable.

Sleeper “Crash” thus had the greater cachet — especially since the wealth could be spread to honor “Brokeback’s” direction, script and music while crowning the hometown favorite.

This phenomenon is hardly new. Author Danny Peary argues that “Since 1927, the one people pick is the one they want to represent Hollywood or the Academy.” Examples from the earliest days abound, from “The Life of Emile Zola” and “Gentleman’s Agreement” to “Hamlet,” a tradition carried on by “Amadeus,” “Out of Africa” and “Schindler’s List.”

Peary, whose tome “Alternate Oscars” argues year by year in favor of his ideas about artistic integrity vs. the Acad’s choices, hears the voters saying, “This is the one we’re proud of, the most representative one. This is the one we want to show the world today.”

That last word, “today,” is the key. Says co-author of “Inside Oscar” Damien Bona, “It’s always important to put yourself in the correct time frame: What else was going on back then?” Hindsight explains alleged “clunkers” like the victories of “Ordinary People” and “Dances With Wolves” over respective Scorsese pics “Raging Bull” and “GoodFellas.”

The serious-minded Redford melodrama, Bona reminds us, “was the odds-on favorite that year. ‘Raging Bull’ was considered ugly and violent; it wasn’t until the end of the decade that it was truly esteemed. And people forget how huge ‘Dances With Wolves’ was at the time,” after months of awful buzz about ‘Kevin’s Gate.’ ”

One Oscar-winning screenwriter calls “GoodFellas” “a perfect movie,” but Costner’s epic was “brave, courageous and raw. He took chances a more seasoned director wouldn’t have.” Not incidentally, these contests pitted two Californian actor-directors opposite a New York iconoclast. In whom would Hollywood take greater pride?

Recipe for best picture gravitas, the record reveals, includes five traits possessed by virtually all honorees since “Wings,” and certainly by those of the last 20 years:

The best picture must have critical backing

Not necessarily unanimous — Bona remembers that “Gladiator” had TV critic types in its arena while print reviewers were less enthused — but the best pic must earn some critical bona fides that help Academy pay attention.

Vet critic Andrew Sarris agrees that an outside imprimatur helps. “If everybody likes something in L.A. and New York and it wins the critics’ awards, that can be a factor.” It at least helps draw the voters’ attention.

It needs at least to break even

“Rarely does an outright flop or even disappointment win,” reports Sarris, citing weak B.O. performer “Citizen Kane” compared with 1941 smash winner “How Green Was My Valley.” It’s tough for a money loser even to get nominated for best picture, the exception being the late December release (like “The Thin Red Line”) that opens big as noms are being made but proves to lack the anticipated legs.

That doesn’t necessarily mean the voters are making their decisions with Variety’s box office chart in theirhands. Grosses are, after all, a measure of attendance. Lightly attended movies are less likely to have been seen by the voters, and it becomes more and more difficult to get their attention at the end of the year because release schedules are so back-loaded.

Its acting must be noteworthy

That’s partly because actors are the largest voter bloc, but principally because good acting tends to be a pic’s most identifiable mark of quality. “I always look for human relationships — actors speaking to actors,” avers an actors branch member.

The last 50 best picture winners hosted 107 nominated performances (more than 10% of all nominated acting over that time). And only four out of the 50 brought home the bacon without at least one acting nominee onboard: “Braveheart,” “The Last Emperor,” the final installment of “The Lord of the Rings” and “Gigi” — and that tuner led to thesp Maurice Chevalier’s winning an honorary award that year.

Even more staggering is that 29 of those 50 winners featured Oscar-winning performances, a total of 38 statuettes representing 20% of a half-century’s acting nods. Strong acting and best picture surely go hand in hand.

Somebody’s got to push it

Peary says, “Get people to see the movie, to get to know you’re out there.”

So the studios or talkshow appearances or Golden Globes attention or something has got to be behind the winner. “It’s become an industry in itself,” Bona notes, “with some publicists making a year-round living off the awards.”

A screenwriter concedes that “like anyone else, members are probably susceptible to some degree to advertising and buzz. But,” he continues, “even that can’t override what one thinks and feels sitting in a dark room watching a film.” Which brings up the fifth and, to some, most significant ingredient:

The best picture must offer an emotionally affecting experience and at least touch on important themes

As Sarris puts it, “generally speaking, they’ve gone with social significance.” Maltin agrees: “Important with a capital I, tackling subjects of significance and relevance.”

But voters all speak in emotional terms. (“It’s what’s moved me most, to tears, laughter, anger, introspection,” says one.) And when it’s head vs. heart, the latter always wins out. Bona cites 2004, when “The Aviator” stood as “a classic example of a film respected rather than liked. It was hard to care about Howard Hughes. But you couldn’t not care about those people in ‘Million Dollar Baby.’ ”

By way of counterexample, some point to last year’s winner “The Departed.” Where, they demand, is the cachet in this slam-bang remake of a genre thriller? But let’s revisit the 2006 field:

  • “Little Miss Sunshine”: Warm and fuzzy, with thematic wispiness conceded even by its partisans.

  • “Letters From Iwo Jima” and “Babel”: Gravitas up the wazoo, but subtitled and esoteric.

  • “The Queen”: Yet more international flavor, and many felt its gravitas was embodied in Helen Mirren’s perf (which won).

That leaves nominee No. 5, a critically praised, emotionally gripping moneymaker featuring half a dozen extolled performances (one Oscar-nominated) and a smart script that explored themes of identity and at least touched on the American immigrant experience.

(The participation of an auteur like Martin Scorses can significantly affect cachet. Peary challenges, “If ‘The Departed’ were the exact same film — same story, same actors, same everything — but the credit read ‘Directed by Bobcat Goldthwait,’ would anybody vote for it? No way.”)

In any event, seen in those terms, “The Departed” isn’t the exception that proves the rule. It embodies the rule.

Some voters are affronted by the idea that selection could be affected by the concept of industry self-image. “That sounds like a producer’s idea,” says one Oscar-winning screenwriter. Insists another, “It’s not a jury of 12 angry men locked in deliberation in a stuffy room where one juror can try to sway the others to arrive at a consensus. I vote for what I think is best to my particular taste, no matter whose eyes are watching.”

Yet their skepticism isn’t inconsistent with “the wisdom of crowds,” theory coined in 2004 by journalist James Surowiecki and alluded to years earlier by Barbra Streisand, when she said of her audiences,” “Individually they may be a bunch of asses, but collectively they are the wisest thing.”

Surowiecki argues that large numbers of individuals, each deciding alone, can come to better decisions than any single group member could make, especially in the presence of four factors that all pertain to Oscar time: diversity of opinion (ever heard of movie buffs agreeing?); independence (“I don’t listen to all the buzz,” a voter proudly states); decentralization (each of the branches contributes its specialized knowledge base); and aggregation (the Academy’s rules and voting procedures bring structure to the decisionmaking).

In this model, the common denominator among so many voters championing different films based on varying criteria might very well be: What choice will bring honor to our Academy and our industry? At least one member of a technical branch who takes his voting very seriously (seeing films multiple times before making a decision) likes the notion.

At first he’s a naysayer: “I won’t vote to send a message. I circle back to the emotional values in the film, how I was affected by it.” But he concedes upon further reflection: “I think that would factor in, if only subconsciously. I absolutely adored ‘Little Miss Sunshine,’ but I just found a grander sense of moment in ‘The Departed.’ Hmmmm.

“I’d think I’d agree that something that really moved me is something I’d be really proud of. I’d be glad to come out of the closet and say: ‘Yes! I voted for that!’ “