Jive-talking Transformers twins Skids and Mudflap are raising questions about racial stereotyping. (Paramount Pictures)

Transformers: Revenge of the Fallen introduces some 40 new mechanized characters of all shapes, sizes and even sexes — but it's a pair of jive-talking bots that critics are singling out as more than just harmless comic relief.

Skids and Mudflap, twin robots disguised as compact Chevys, constantly brawl and bicker in rap-inspired street slang. They're forced to acknowledge that they can't read. One has a gold tooth.

As good guys, they fight alongside the Autobots and are intended to provide comic relief. But the traits they're ascribed raise the spectre of stereotypes most notably seen when Jar Jar Binks, the clumsy, broken-English speaking alien from Star Wars: Episode I — The Phantom Menace, was criticized as a racial caricature.

Compared to Stepin Fetchit, Jar Jar Binks

Wall Street Journal film critic Joe Morgenstern described Binks in 1999 as a "Rastafarian Stepin Fetchit," a reference to a black character from the 1920s and '30s that exploited negative stereotypes for comic effect. Extending that metaphor to the Transformers sequel was AP Movie Critic Christy Lemire, who calls Skids and Mudflap "Jar Jar Binks in car form."

And Manohla Dargis, film critic for The New York Times, takes it a step further, writing that the Transformers characters were given "conspicuously cartoonish, so-called black voices that indicate that minstrelsy remains as much in fashion in Hollywood as when, well, Jar Jar Binks was set loose by George Lucas."

Director Michael Bay insists that the bumbling bots are just good clean fun.

"We're just putting more personality in," Bay said. "I don't know if it's stereotypes — they are robots, by the way. These are the voice actors. This is kind of the direction they were taking the characters and we went with it."

TV actor Reno Wilson, who is black, voices Mudflap. Tom Kenny, the white actor behind SpongeBob SquarePants, voices Skids. Neither immediately responded to interview requests for this story.

Bay said the twins' parts "were kind of written but not really written, so the voice actors is when we started to really kind of come up with their characters.

"I purely did it for kids," the director said. "Young kids love these robots, because it makes it more accessible to them."

Screenwriters Roberto Orci and Alex Kurtzman said they followed Bay's lead in creating the twins. Still, the characters serve no real purpose in the story, and when the action gets serious, they disappear entirely, notes Tasha Robinson, associate entertainment editor at The Onion.

"They don't really have any positive effect on the film," she said. "They only exist to talk in bad Ebonics, beat each other up and talk about how stupid each other is."

Negative stereotypes used as comic relief

Hollywood has a track record of using negative stereotypes of black characters for comic relief, said Todd Boyd, a professor of popular culture at the University of Southern California's School of Cinematic Arts, who has not seen the Transformers sequel.

"There's a history of people getting laughs at the expense of African-Americans and African-American culture," Boyd said. "These images are not completely divorced from history even though it's a new movie and even though they're robots and not humans."

American cinema also has a tendency to deal with race indirectly, said Allyson Nadia Field, an assistant professor of cinema and media studies at the University of California, Los Angeles.

"There's a persistent dehumanization of African-Americans throughout Hollywood that displaces issues of race onto non-human entities," said Field, who also hasn't seen the film. "It's not about skin colour or robot colour. It's about how their actions and language are coded racially."

If these characters weren't animated and instead played by real black actors, "then you might have to admit that it's racist," Robinson said. "But stick it into a robot's mouth, and it's just a robot, it's OK."

But if they're alien robots, she continued, "why do they talk like bad black stereotypes?"

Bay brushes off any whiff of controversy.

"Listen, you're going to have your naysayers on anything," he said. "It's like is everything going to be melba toast? It takes all forms and shapes and sizes."