With cable ratings rising, research suggests fewer viewers are beginning their prime-time TV experience by checking out the broadcast networks first -- if they aren’t tuning into a particular program. Research from GfK shows the percentage of viewers (18-49) who cite a broadcast channel as one of the top three they turn to has dropped from 49% in 2008 to 42% this year. Those mentioning a cable network among the first three has risen from 80% to 85% over the same period. The results come from an online survey. Cable has been above 80% in 2004, 2008 and 2012. Broadcast channels have fallen steadily from 52% in 2004. Also, undergoing a change is how 18-to-49 find out about prime-time programming, a trend network marketers are continually trying to stay a step ahead of. Social media is on the rise, up to 6% from about zero in 2008. Also instructive, is TV Guide continues to drop, from 6% in 2008 to 4% this year. (The figure was 9% in 2004.) GfK reported a more precipitous drop for daily newspaper listings, with a decline from 8% in 2008 to 2% in 2012. The four leading ways 18-to-49s find out about prime-time programs have seen declines, but still lead the choices. In 2012, flipping channels, using an interactive program guide and “just know when on” all came in at 38% among survey participants. Perhaps a sign that viewers are zipping through more commercials with DVRs, TV ads saw a major drop from 30% four years ago to 19% this year. Data shows the number of 18-to-49 who believe the amount of ads in prime time is greater than in other dayparts, increased from 59% in 2008 to 63% this year. But 69% believe the number of prime-time ads, which is the same as a year or two ago — and the same percentage as four years ago. Network sales executives might be heartened by data showing 40% of those surveyed say prime-time ads help them “become aware of new products better,” up from 35% in 2008. The figure was, however, 47% eight years ago. Prime-time video consumption has seen a decline in the number of 18-to-49 year-olds using a TV set in the 8 p.m. to 9 p.m. hour from 83% in 2008 to 64% this year. Watching streaming video (7%) and recorded programming (8%) has accounted for much of the drop. The survey asked participants to identify viewing habits in the hour the previous day.