Behind Ernie and Bert is a researcher's sharp eye. Just how does television affect children? asks Valeria Lovelace, director of research

Those rollicking ``Sesame Street'' episodes starring Big Bird and friends don't just spring lightly from a scriptwriter's imagination to the screen. Experts with training in education and child development cast a sharp eye on them before you ever see them. Foremost among these is Valeria Lovelace, whose post as ``Sesame Street's'' director of research gives her a strong say about what's aired on the perennially popular show.

During an interview here, however, she hardly seemed a hard-eyed researcher with a PhD in social psychology. It doesn't take much to summon a smile and laugh from her - just the memory of Sesame's head writer greeting suggested script changes with, ``but that's not as funny.''

Ms. Lovelace's work involves constant give-and-take with the creative types at Children's Television Workshop, ``Sesame Street's'' originator.

But from the collaboration between writers and educational researchers ``you get some truly exciting things,'' she says.

For instance, a writer once tossed out the idea of a friendship between Slimy, the show's worm Muppet, and a caterpillar. What happens to their relationship when the caterpillar changes into a butterfly? Will Slimy lose his friend?

Those questions sparked some research to find out what in fact happens to a transforming caterpillar, as well as exploration of the metaphorical lessons in human relationships - can people still be friends when their circumstances change?

But the heart of Lovelace's research is that crucial, still not fully answered question, Just how does television affect children?

``We go out and watch children watching `Sesame Street' and measure their attention, then we create graphs on what they're watching and what they're not.'' She and her staff also devise games and activities to try to assess whether young viewers have actually learned what the show's creators had hoped - things ranging from letter and number recognition to positive social attitudes.

That information, indicating what works and what doesn't, is then fed back into the programming mill. Research insights give writers an idea of what might need ``more definition,'' or clarifying, before kids will grasp it, Lovelace explains.

Case in point: a ``Sesame Street'' segment on adoption. Gordon and Susan, two of the street's human residents, decide to adopt little Miles. The producer and writer wanted children to understand why this is done, and what it means to the people involved. But testing showed that the message wasn't coming through clearly, says Lovelace.

Somebody came up with the idea of focusing on ``care'' - that Susan and Gordon wanted someone to care for, and the baby needed someone to care for him. That approach worked better, but you have to keep in mind that children interpret things their own way, Lovelace observes with a chuckle. One little viewer heard ``a doctor'' every time the script said ``adopted.''

The ``Sesame Street'' team perpetually sets and revises goals, Lovelace notes. Each segment of the show has a goal, and often more than one. Making kids more aware of writing is a current target. Not so much penmanship or spelling - traditional emphases - but the creative process of getting ideas down on paper, with little concern about form.

``Even scribbling by preschoolers'' is a form of writing, says Lovelace. ``You should encourage them to `read' it back to you, even though you can't read it.'' Small children grasp the idea of being an author, she says. The show provides ``models'' of children engaged in creative activities and of adults appreciating their efforts.

Clearly, there's a message for parents here. ``Our assumption is that kids are watching by themselves, but our hope is that parents will be watching with them.

``Research shows that kids learn more if parents are watching with them,'' says Lovelace. She realizes the practical difficulties in this, but encourages mothers and fathers to catch even bits of the show between other household tasks.

Has ``Sesame Street,'' which has always tried to be sensitive to social trends, any new developments down the road?

For one thing, says Lovelace, the show wants to put more emphasis on male-female relationships.

Hence Luis and Maria, longtime Sesame Streeters, will be married on the air, in an effort to give young viewers some idea of what marriage and love ought to mean.

On the Muppet side of the street, some new female characters will take up residence: Alice, Snuffy's little sister, and a rather overbearing actress named Meryl Sheep.