Although it's meant to be a satirical comedy, "The Incredible Shrinking Woman," now at theaters, suggests that partners Lily Tomlin and screenwriter Jane Wagner have yet to recover from the shock of their last unfortunate collaboration, "Moment by Moment."

The source material, Richard Matheson's science-fiction novel "The Shrinking Man," was turned into a modest but effective thriller in the late '50s. So before "Shrinking Woman" begins disillusioning you, the prospect of Lily Tomlin as a "little woman" who must cope with the inconvenience, indignity and terror of growing downright microscopic sounds tantalizing. It's an idea that you'd like to see succeed.

The imaginative oomph may have gone out of the project when Universal maneuvered John Landis into directing "The Blues Brothers" instead. Landis had intended to do "Shrinking Woman" as a splashy comic fantasy, but the finished film -- directed by Joel Schumacher -- seems conceived on the cheap and shot as if it were earmarked directly for television. Tomlin's character, Pat Kramer, inhabits a sitcom environment that Wagner systematically belittles but fails to transcend.

Naively content, Pat presides over a chintzy, pink-toned nest in a plasticized subdivision called Tasty Meadows, where the neighbors seem to be dressed for an ongoing fruit-sherbet festival and shout friendly greetings in the form of product endorsements. Pat and hubby Vance (Charles Grodin, now the most ubiquitous domestic male in American movies), an eager-beaver advertising executive, are blissfully compatible. They have custody of two professionally bratty TV kiddies, a shaggy dog and a superfluous Mexican maid. Tomlin doubles as her own neighbor, a prim clubwoman named Judith Beasley who also peddles a door-to-door line of concoctions called Flow Naturelle, a facetious competitor of Avon and Amway.

We're asked to play along with the gag that Pat begins shrinking due to constant exposure to chemical additives and synthetic substances. It would seem wittier to illustrate the dilemma in vividly gradual stages. Instead, the filmmakers jump from minute signs of shrinkage to extreme conditions, with Pat reduced to the size of a toddler and then a dollhouse miniature.

Scanty to begin with, the sight gags are also botched with deflating frequency. For example, determined to keep serving meals to her beloved family, a diminutive Pat overturns an oversized salad bowl and platter while trying to maneuver them off the kitchen counter. Unfortunately, the payoff is shot from such an oblique reverse angle and cut so awkwardly that the comic potential is trashed along with the meal. The only sequence that attempts to recall the terrifying aspects of "The Incredible Shrinking Man" also degenerates into a garbagey mess: Trapped in the disposal, Pat is beaned with eggshells, slices of toast and sundry leftover glop. Optical invention is also kept to a cost-conscious minimum. The illusion of shrimpiness is conveyed almost exclusively by posing Tomlin on or against oversized props.

Feeble as it plays, the slapstick might generate a certain silly momentum if the script weren't fatally weakened by Wagner's editorial meditations. Pat falls into the clutches of a sinister conglomerate, the Organization for World Management, eager to exploit her as a guinea pig in a top-secret "World-Shrink Plan." Resorting to a voice-over narration that flits in and out of the continuity, Wagner has the heroine confide, "These people were so big that the only way they could become bigger was to make the rest of us smaller." These passages may reflect a sensibility conditioned by too many vaguely guilty years of association with television.

Tomlin would certainly be better off as a comic performer if she had more incredible obstacles to overcome and fewer dreary lines to read. The talents of Grodin, Henry Gibson, Ned Beatty, Elizabeth Wilson, John Glover and Pamela Bellwood are also squandered on negligible roles, but a young comic named Mark Blankfield manages to ingratiate himself as a slow-witted but fleet lab assistant who comes to the heroine's aid. Rick Baker also does an amusing bit in his gorilla suit, although I wish he'd resisted the temptation to swipe a bit from Clyde, the inimitable orangutan of the Clint Eastwood movies. It's a bit shameful to see a man in an ape suit stealing schtik from a real ape.