Word of mouth is the No. 1 influence on young viewers in deciding what to watch on TV, and promotion executives have to become better at viral marketing to take advantage of that, according to a study released at the Promax BDA Convention in New York Wednesday.

The good news for promotion executives is that TV promotion is the next most effective way to reach those young viewers, said Brent Magid, CEO of Frank N. Magid Associates, the research company that put together the report.

Magid looked at the 79 million viewers between the ages of 9 and 28, a group it calls the Millennials, which is larger than the Baby Boom generation, which encompasses 78 million.

Millennials multitask, consuming 20 hours worth of media a day in seven hours of actual time.

The group is composed of communicators, including “super disseminators” who pass on messages about TV to six or more people on a regular basis.

Mr. Magid said the key was for promotion executives to find triggers to get these super disseminators to pass on their messages.

“We are not the enablers of viral marketing like we should be,” he said.

Messages most likely to be passed on are likely to be funny and entertaining, scary or freaky, or appealing to lifestyle, he said. The messages also have to be in a form that’s easy to pass along.

Mr. Magid said traditional TV promos are the only other source of info about TV shows that influences the Millennials.