by MATTHEW HAYS

Pseudo science-fiction movies aimed at the teen demographic can be the perfect way to start a morning. Loaded with stoner can-you-imagine-what-it'd-be-like-if logic and coated in after-school-special simplicity, movies don't get much easier to digest than this.

And The Butterfly Effect is a pretty good example of teen sci-fi, based on the kind of high concept that undoubtedly struck a screenwriter after their sophomore acid trip. Here, Ashton Kutcher plays a young man torn by the psychological scars of a tortured childhood. Trouble is, poor dear Ashton can't remember any of the really bad bits due to chronic blackouts. Lucky for him (and the movie's internal logic), all he has to do to jar his memory is read one of his detailed diaries and voilà - he's back in time, able to change things around and alter the future. (Each leap back in time, notably, is punctuated by Ashton having a severe nose bleed.)

There's this girl Ashton's hopelessly in love with (played by chameleonesque Amy Smart) and every time he goes back in time to try to correct Smart's situation, it seems each outcome is worse than the last. Someone stabbed someone inadvertently, or someone got traumatized by doing a kiddie porn flick, or someone got lung cancer after getting hooked on cigarettes years ago - that sort of thing.

The concept has been done before in pop culture, of course. Kurt Vonnegut catapulted his anti-hero about in time in Slaughterhouse-Five to great effect. And then there's that famous episode of Star Trek in which, if I recall correctly, William Shatner must avoid altering world history or else Joan Collins would turn into Adolf Hitler (or something like that).

The Butterfly Effect has its entertaining moments. And Kutcher, up till now mainly relegated to dimwitted comedy, indicates that he might actually have some skill as an actor. But once the movie's high concept (whoa, like fate is such a heavy thing!) wears thin, the Butterfly Effect itself pretty much wears off.

The Butterfly Effect opens Friday, Jan. 23

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