NEW YORK (AP) ― Actors make physical transformations for roles all the time; it’s what they do.

Still, many have found it truly stunning to see Sharon Stone ― who at 55 still looks unnervingly like the sleek, blonde, leg-crossing femme fatale she played two decades ago in “Basic Instinct” ― appear dark, severe, ungainly and nearly unrecognizable in “Lovelace.”

“NOBODY recognized her,” says Amanda Seyfried, who plays Stone’s daughter, the “Deep Throat” star Linda Lovelace, in the film that opens Friday. “Harvey Weinstein, if I remember correctly, did not know that Sharon Stone was in it. She’s that good.”

But Stone says that while she’s happy people are shocked, they may not realize that she also had to transform herself to play that uber-sexy “Basic Instinct” role back in 1992.

“It’s funny, because when I played ‘Basic Instinct,’ everybody thought I was playing something closer to myself,” Stone said in a recent interview. “But in fact I totally transformed myself to play that character. I didn’t know how to go around looking like that.”

Of course, Stone added, “It was more fun to continue to look glamorous and closer to that part ― obviously I’m not going to go out and look more like this character, Dorothy Boreman, because I don’t want to! But I’m not anything at all like that (Basic Instinct) part, and I’m not like this part.”

In any case, she’s enjoying the reaction. “I like it because I feel, like, I did it!” she said, her voice lowering to a conspiratorial whisper. “Oh, I really did it!”

Stone has a history of surprising people, both off screen ― with occasionally controversial red-carpet comments ― and on. She may have been in legendary sex-symbol territory after “Basic Instinct,” but she surprised even herself by earning the 1996 Golden Globe for Martin Scorsese’s “Casino,” beating out heavyweights like Meryl Streep, Susan Sarandon and Emma Thompson. (She also received an Oscar nomination for her admired performance as a high-priced call girl.)

Her later films may not have been quite as successful, but she remains a Hollywood fixture ― a red-carpet favorite, and a formidable fundraiser for AIDS research ― and “Lovelace” co-star Seyfried was gushing in praise of Stone as an on-set mentor.

“I wanted to be so good for her,” Seyfried said. “I was terrified that I was going to do my job poorly. But ... she just said the right things. She helped me. She slapped me into the role.”

Seyfried was speaking metaphorically AND literally: At one point, mother slaps daughter. Another scene is even harder to watch: Lovelace’s mother refuses to allow her daughter to return home and take refuge from her physically abusive husband.

Stone, a single mother of three sons, said she focused on the intentions of her character, not her actions.

“I think that my character felt she was being a good parent by guiding her daughter into keeping her commitments,” she said. “I think in that time, and from her ethical standpoint, she felt that keeping her commitment as a wife, growing up, staying in a mature marriage ... that was giving her daughter good advice. This was a different era.”

The movie is based on the 1980 memoir, “Ordeal,” by Lovelace, who eventually renounced her porn career and became an anti-pornography activist. (She died in 2002). It tells a dark story of Lovelace’s virtual enslavement to her husband, Chuck Traynor, who, she wrote, forced her into making “Deep Throat,” kept her earnings, even forced her into prostitution. But Stone noted that Lovelace, after all, ended up leaving Traynor, marrying again and having children.

“She took her life and transformed herself into something else,” Stone said. “I think the lesson is that it’s not how we fall ― it’s how we get up.”

Though she still cuts a glamorous swath wherever she goes, and is meticulous about her image, Stone says she feels comfortable with the inevitability of aging ― and the different acting roles it will bring.

“You know, I’m a grown-up lady,” she said. “I feel certain that I’m going to play adult characters and mothers and ultimately grandmothers. I feel sure that I have gracefully surrendered the things of youth!”