"If you haven't acquired a new thought or dropped an old one within the past six months," declares Springfield, Va., social worker Susan Grossman, "check your pulse. You may be dead."

Just as people scrub every corner of their homes in the spring, "now's a great time," she says, "to spring-clean your mind. . .shake out the dust from the attic of your brain."

Among her "get-out-of-your-rut" ideas:

* Read a magazine in a field you know nothing about: engineering, science, psychology, auto mechanics.

* Make the familiar strange. Pretend you're a visitor from Planet Twelve and observe humans at the shopping mall, or at the zoo.

* Observe a day of silence. Unplug the phone, turn off the TV, radio, stereo.

* Dream up an invention. For example: A "car-wash" type machine for humans too tired to bathe.

* Go on an adventure day (especially fun with children). Walk, bike or drive and "just see what happens." Chores, plans, schedules not permitted.

* Invent a word. "Grumblitz" could be an early morning fight. "Sperky" a refreshing soft drink.

* Read a biography. Of someone in an area you know little or nothing about.

* Create the unique from the ordinary. Take a common object and consider what could be added, subtracted, revised to make it better or different. A spoon with a collar to shield you from squirting grapefruit?