HOT FACES: ROBERT DOWNEY JR., ELIZABETH PENA

You may have heard this before concerning performers, but Robert Downey Jr. is really much happier firing off puns and quips about the world’s foibles than addressing his own hopes and fears.

The 22-year-old son of director Robert Downey Sr. (“Putney Swope”) gets through an interview all right (and then some) but he insists an actor’s temperament is more suited to observation than self-revelation.

With Downey, those observations are of a caustic, slightly scabrous nature--much of his conversation isn’t printable in a family publication--but he’s quick to add that he’s “beginning to learn to relate this big, bad old world to what’s going on inside of me,” and he’s quite eager to describe the world . . . as he sees it.

Which is why the star of the upcoming “Pick Up Artist,” scheduled to open in August, was eager to hunker down on the Beverly Hills location of “Less Than Zero” (in which he plays a wisecracking, cocaine-addicted young rich kid) with a reporter and reflect on what happens when an actor gets a featured role in a hit motion picture (last summer’s “Back to School,” starring Rodney Dangerfield):

“It’s always nice to have people come up and say, ‘You’re great, you made me laugh,’ ” he says. “But then there are times when the cute little girl sidles up and drawls, ‘I just left my boyfriend over in the corner ‘cause I like you better,’ and I just say, ‘Go on back, you’ll make him feel bad’--and she shouts back. . . . And then the boyfriend, who of course is about 6 foot 8, starts walking over and he doesn’t look pleased. . . .”

Downey is candid about the discomforts and joys that are part of the actor’s trade. “I’m always happy that the rent is getting paid, that’s No. 1--I learned that from my dad,” he says. “And certainly there are a lot of pains in the butt about the gig; not the public side so much as the tremendous weight of responsibility and expectations placed on you, and maybe at too young an age.”

Sitting up in a barber’s chair in his trailer, Downey was able to put his temporary concerns about work--and even growing up in general--into a neat philosophical perspective and spoke about it quietly, with an uncharacteristically straight face.

“The biggest thing to get over for me right now . . . is to avoid blowing things out of their proportion,” he says haltingly, rocking in the chair a little. “It’s the natural thing to do, I guess, when you hit that first rush of having your work validated with success; you think, ‘The world and I are one being.’

“But that’s all bull. I mean, the starving guy in Ethiopia is a lot more concerned about not starving and keeping the flies away--and his worries are just as important as mine. The biggest thing you think your problem is, that’s how big your field for worry is.”

The philosophical overview--which Downey sarcastically insisted was “the most searingly original thing that has ever been uttered, I’m sure”--has at least helped the young actor get a more realistic grip on how he fits into the Hollywood machine, and what he wants to accomplish there.

“All I know is that now, when some kind of derivative, completely unimaginative (film) that stinks of ‘boffo box-office’ is offered to me, I can think twice, even three times. I may look more favorably on something that’s weird, that has strange juice running through it.

“But then again, if I’m broke at the time,” Downey continues, broadly exhibiting his empty pockets, “it might not look bad. But that’s no real reflection on an actor, if he cashes in from time to time. They asked Richard Burton why he did this or that part, and he’d say (imitating Burton’s Welsh growl), ‘For the money , you idiot.’ No harm, no foul.”

So far, at least, Downey has had it both ways. Besides “Back to School” and “Weird Science,” there are “Zero” (“A really dark idea, this one,” he commented) and “The Pick-Up Artist,” in which an ace Casanova (Downey) meets up with a girl (Molly Ringwald) who overmatches him. There are also New Century/Vista’s “Johnny B. Goode” and “Rented Lips,” which gave Downey a chance to work with his dad.

“I feel so free and relaxed with the old man directing,” Downey says with a slow smile. “A lot of improvisation, and really looking for character. At first I had trouble accepting his suggestions as to what this guy I was playing should be. Generational conflict followed. But, of course, once I listened to him”--Downey snaps his fingers--”bam! there it was.

“It was the most freeing experience, in a lot of ways; and, sensibly enough, it was my lowest-paying gig to boot. There’s a lesson in there somewhere, for those who might care to find it.”