But Wheelock College education professor Diane Levin says Rock 'n' Roll Ernie isn't such a great toy. He was created specifically to rock, she said, so kids don't stretch their imaginations and get bored easily.

Despite the analysis, Ernie is a huge seller.

Over the weekend, about 150 academics, toy marketers and retailers gathered at Wheelock for what organizers said was the first-ever conference for those who sell toys and those who study the effects toys have on kids.

By discussing such topics as Ernie's apparent contradictions, organizers hoped to narrow the gulf between researchers and the toy industry.

They also hoped to get both sides thinking about how play affects a child's development, how toys influence play and how to create more toys that will be both educational and profitable.

``I believe there can be an intersection,'' said Robin Sayetta, who markets the Discovery Channel's Exploration toy line.

The ``Playing for Keeps 2000'' conference was conceived by Wheelock professor Edgar Klugman and John Lee, founder of Learning Curve International, which sells developmental toys.

Lee on Saturday compared toy researchers and sellers to two groups on opposite sides of a playground who never interact, despite common interests.

He believes that has to change. Toys are relentlessly advertised, and parents often aren't able to screen what ads their children are seeing.

In addition, he said, neither parents nor toy makers always appreciate how important play is to a child's development.

For instance, building toys with Legos allow kids to conceive projects, solve problems and improvise. But toys such as Ernie, which are based on TV characters, direct kids toward conclusions that fit the framework of the show, and don't allow their minds to stretch. Violent toys can be worse, he said.

In her talk, Levin demonstrated a wrestling doll for ages four and up that begs for mercy when you twist its arm and complains when you smash its nose.

A segment by anti-toy violence activist Daphne White featured guns galore and a deadly toy worm, intended for all ages, whose packaging promises the user can ``wreak havoc on your enemy in a game of revenge and mean-minded cruelty.''

White said that's how children learn to be aggressive.

``We're really saturating our kids' world with violence,'' she said.

Public concern over youth violence has opened doors for discussion with toy manufacturers. And concern about corporate responsibility has proven that environmentally or socially conscious products will sell, said Patrick Rafter, spokesman for the Waltham-based online toy vendor toysmart.com.

But as activists clamor for changes, Sayetta said they need to remember that toy companies must make profits, and not all would agree on the dangers of toys such as the complaining wrestling doll.

In other words, she said, concessions can't be one-sided.

``I think it's the beginning of a dialogue,'' Sayetta said. ``Maybe this is just putting it on the radar screen.''

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[Updated 3/20/2000]