NBC NATIONAL NEWS — Pediatricians have long said parents should limit the amount of television their children watch.
Now new research suggests moms and dads may also want to limit the kind of shows kids see.
"We shouldn't just assume that because they're being quiet and in the living room, that everything is okay," says Dr. Michael Rich of the Center On Media and Child Health.
The new study is a small one, involving just 60 4-year-olds.
Researchers randomly assigned the kids to one of three groups -- either play with crayons, watch a slow-paced, educational cartoon, or watch a fast-paced cartoon -- in this case, "SpongeBob Squarepants".
After doing one of these tasks for nine minutes, the researchers assessed the kids' ability to focus and problem solve.
"The children who watched the fast-paced cartoon performed significantly worse," says Dr. Dimitri Christakis.
Experts say kids' developing brains don't have enough time to process fast-paced media.
"These children's brains were actually tired from all that stimulation and they weren't as able to then focus the way they otherwise would be able to," Dr. Christakis explains.
"If you are given more time to absorb a scene, to understand what goes on, you are able to interact with it, with your own questions and your own ideas," adds Dr. Rich.
"SpongeBob" is one of Nickelodeon's most popular shows, and is marketed to kids over age 6.
In a statement, a Nickelodeon spokesman said:
"Having 60 non-diverse kids, who are not part of the show's targeted demo, watch 9 minutes of programming is questionable methodology and could not possibly provide the basis for any valid findings that parents could trust."
There's no evidence to suggest the short-term cognitive deficits found in this study translate into long-term problems.
While SpongeBob himself may not be the enemy, experts say parents should remember kids brains are like sponges...soaking up everything they see.
The typical preschooler watches two to four hours of television a day.