One of the more hackneyed movie-plot devices of the past 100 years is amnesia, yet here we are in the 21st century and it's still being trotted out in major Hollywood motion pictures.

If you've been looking for evidence that Hollywood has run out of original ideas, look no further than "Unknown," with Liam Neeson as Dr. Martin Harris, an American in Berlin who loses his memory after being rescued from a taxi that crashes into a river. Only flashes of memories remain, which he tries to piece together with the help of the beautiful cabbie who saves his life as they elude unknown assassins.

If you're thinking, "That sounds like 'The Bourne Identity,' " give yourself a gold star. That 2002 thriller starred Matt Damon as Jason Bourne, rescued from the water to find he has amnesia, so he looks for answers with help from a beautiful stranger as they elude assassins.

But none of this is really meant to disparage those movies. "Unknown" is pretty good, with a dandy car chase and a climax that is expected, yet surprising in the way it occurs. And, of course, "Bourne" is very good. Both are examples of creaky material getting a reboot that works well enough to entertain for a couple of hours.

In fact, "The Bourne Identity" remains the biggest moneymaker on the subject, spawning a pair of highly successful sequels, with another in the planning stages. Even that film was a remake, though, having been a two-part TV miniseries starring Richard Chamberlain in 1988.

But even by 1988, the amnesia plot had been done to death, most often in the service of mysteries. And that includes a few by the Master of Suspense, Alfred Hitchcock himself — who may have forgotten he had already used it when he decided to use it again. The first time was with the character played by Norah Baring in Hitchcock's "Murder" (1930). Next was Gregory Peck in Hitchcock's classic "Spellbound" (1945). And how about Tippi Hedren as the title character in "Marnie" (1964)?

Peck tried it again with the very Hitchcock-like film "Mirage" (1965), and others in thriller trappings include George Peppard in "The Third Day" (1965), Nicol Williamson (as Sherlock Holmes) in "The Seven Percent Solution" (1976), Jennifer Jones in "Love Letters" (1945), William Powell in "Crossroads" (1942), Elizabeth Taylor in "Suddenly Last Summer" (1959), Robert Taylor in "The High Wall" (1947), both Frank Sinatra and Laurence Harvey in "The Manchurian Candidate" (1962), and Tom Berenger in "Shattered" (1991).

Whew. And that just scratches the surface. We haven't even gotten to the 1940s' 10-film "Crime Doctor" franchise, in which a famous criminal psychologist has forgotten he was once a criminal himself.

Comedy has also made a lot of hay with amnesia. Charlie Chaplin's Little Tramp suffers from it in "The Great Dictator" (1940), and William Powell forgets he's a con artist in "I Love You Again" (1940). When Joel McCrea loses his memory late in "Sullivan's Travels," it lands him in prison. Rosanna Arquette thinks she's Madonna in "Desperately Seeking Susan" (1985), Goldie Hawn forgets she's rich and spoiled in "Overboard" (1987), Christopher Lloyd's Uncle Fester in "The Addams Family" (1991) thinks he's an imposter, and Ellen DeGeneres, in animated form, forgets, well, most everything in "Finding Nemo" (2003).

Heck, Christina Applegate managed to be an amnesiac for an entire two-season sitcom, "Samantha Who?"

Then there's the sci-fi twist, as with Peter Weller in "RoboCop," whose memories of his former nonmetallic life return in flashes; Arnold Schwarzengger's entire life is fictionalized to accommodate his amnesia in the first third or so of "Total Recall" (1990); Rufus Sewell has no idea who he is in the computer-graphics-heavy "Dark City" (1998); Jim Carrey and Kate Winslet have their memories erased by choice in "Eternal Sunshine of the Spotless Mind" (2004); and Sam Worthington, before he turned blue in "Avatar," was a forgetful cyborg in "Terminator Salvation" (2009).

And, of course, melodramas have had their share of amnesia plots, starting with the film that might be considered the go-to granddaddy of the genre, "Random Harvest" (1942), in which Ronald Colman suffers from memory loss, not once but twice. World War I brings it on the first time, landing Colman in a hospital. Later, he marries Greer Garson and builds a new life. But then, after he's struck by a car, memories of his new life — and Garson — are erased, as he reverts to the identity he had before the war!

In "Mister Buddwing" (1966), James Garner wakes up on a park bench and then wanders around Manhattan, trying to figure out who he is, and along the way encounters, among others, four women (Suzanne Pleshette, Jean Simmons, Angela Lansbury, Katharine Ross) who bring on flashbacks.

Harrison Ford's amnesia in "Regarding Henry" (1991) makes him a nicer person, also a common movie plot device. And Carrey finds his memory wiped clean after a car crash in the Frank Capra-style "The Majestic" (2001), as a 1950s Hollywood screenwriter who resembles a local soldier lost in the war, so he assumes he must be the guy, and no one discourages the idea.

But perhaps the wackiest plot is the one where someone loses his or her short-term memory nightly, while sleeping, awakening each day with no recollection of anything that happened the day before.

That's perhaps most famously used in "Memento" (2000), as Guy Pearce tries to solve the puzzle of his wife's murder but keeps forgetting what he has investigated the day before, so he begins leaving himself notes and clues (even tattoos) in the daily hope of picking up where he left off.

Comment on this story

But it's also been used for comic fodder. Dana Carvey in "Clean Slate" (1994) is a private detective who forgets each night what he's supposed to testify to in a crime boss' murder trial. And Drew Barrymore forgets each night that she has fallen in love with Adam Sandler in "50 First Dates" (2004) — or maybe she's just using it as an excuse.

And maybe we should also include "Groundhog Day" (1993), since everyone except Bill Murray seems to have daily amnesia.

I'm sure there are more, if I could only remember them.

e-mail: hicks@desnews.com