Oh, no. Not again.

In the horror film "Dark Water," 9-year-old Ceci (played by Ariel Gade) is in her bedroom, quietly singing "Itsy Bitsy Spider," which she sang with her class earlier that day. Then, all at once, you hear a second voice, a ghost girl's disembodied whisper, joining Ceci and suddenly a memorable childhood song becomes a sinister latchkey into a world of terror.

Turns out the ghost girl -- and this is no surprise to anyone who's seen more than two Hollywood horror films in his life -- was murdered.

The kiddie song as a creepy motif will strike few of us moviegoers as earth-shatteringly new. We know we've seen (and heard) this ploy somewhere before in some movie -- or was it three or four? Like the dogs in Pavlov's conditioned reflex experiments, we know the two-part reaction we're supposed to have. At first, the familiarity of the song brings us straight back to childhood. Fuzzy, cuddly memories flood in, and that warm bath of lost innocence washes over us. Then comes the second part, the incongruity: That's a dead child singing. Suddenly, those cherished associations are corrupted. And quite possibly for the rest of our lives we'll think of this mediocre scare flick every time we hear that song. Oh, thanks a lot.

And speaking of child-oriented tiresome horror tropes, "Dark Water" hauls out the good old Imaginary Friend. When her mother (Jennifer Connelly) challenges Ceci about talking to herself, the little girl claims she's conversing with "Natasha." And in the recent "Hide and Seek" -- the title of course references a child's game -- Robert De Niro plays father to a traumatized daughter, Emily (the ubiquitous Dakota Fanning), who claims the murders that keep happening in their house are the fault of her invisible pal, Charlie.

Nursery songs and rhymes, imagined buddies, ghost children, sinister dolls (in five "Child's Play" movies and counting), and of course children simply placed in harm's way -- this pandemic is the real horror story.

Back in the old days, childishness used as a counterpoint to horror really meant something. In James Whale's 1931 "Frankenstein," a little girl sits on a riverbank with Frankenstein's monster playing with flowers. The monster watches flowers floating down the river. He runs out of flowers to toss. Hmmm, he wonders. Maybe the girl will float too. So much for innocent childhood games.

And in the infamous "Daisy ad" put out by supporters of President Johnson in the 1964 presidential campaign, a very young girl (with tweety birds in the background) counting out numbers in an innocent ramble ("one, two, three, four, five, seven, six, six, eight, nine") runs parallel to a man's voice intoning a countdown. The ad -- so provocative it was yanked after just one airing -- zooms in on the girl's eye, upon which is superimposed a nuclear explosion.

This chilling use of a child's innocence still felt fresh (and subtle) for a few decades, whether it was Mia Farrow singing a lullaby at the beginning of 1968's chilling "Rosemary's Baby," or sweet little Regan (Linda Blair) leaving a girlish taped message for her dad in 1973's "The Exorcist" (you know, just before she started talking like Lil' Kim). And who can forget 1980's "The Shining," in which young Danny (Danny Lloyd) has an imaginary pal, suggested by his twitching forefinger, who speaks in an eerie mutter about "redrum"? When we realize he's saying "murder" in reverse, somehow, we're utterly spooked. We've seen a brilliant use of the ploy.

In "Tarnation," Jonathan Caouette's stunning intimate documentary about struggling with his own mental demons and those of his mother, at one point a childlike song becomes genuinely (and justifiably) disturbing: His mother, Renee, returns from sessions of electroshock therapy and, as she's holding a pumpkin, she laughs uncontrollably and sings "You do the pumpkin," over and over.

When it works, it works. And during those times, the difference between well-wrought horror that pokes at our deepest fears and films such as "Dark Water" and "Hide and Seek," which simply stab at our sensibilities with a sort of lazily imagined sadism, are all too clear. These invasions of our collective nursery aren't terrifying any more. They're just deeply irritating.

Dakota Fanning has -- no surprise here -- a creepy invisible friend in last winter's "Hide and Seek." Ditto for Ariel Gade (with Jennifer Connelly) in the recently opened "Dark Water."Boris Karloff and Marilyn Harris, setting the standard in 1931's "Frankenstein."