People who use Twitter while watching TV have higher levels of recall of ads

"The research is clear that Twitter leads to more commercial viewing, but are Twitter users more impacted by ads? Working with Millward Brown Digital, we conducted a study of more than 7,500 respondents to compare the impact of TV ads among people who watched TV with and without Twitter.
We found that viewers watching TV without a second-screen had an average TV ad recall of 40%. But among those using Twitter, ad recall was significantly higher: 53%. These viewers were also 13% more likely to discuss shows and 3% more likely to recommend programs, making TV x Twitter a win/win for advertisers and networks alike.
Our research also demonstrated a difference in the ability for a TV spot to help build a brand. We found that the impact of a TV commercial, as measured by a lift in brand favorability (the likelihood for a viewer to rate a brand ‘excellent’ on a five-point scale) was 7%. Among those viewers who were also tweeting, the lift was 18%. The lift in purchase intent was also higher among those tweeting: 30% compared to 16% in the TV-only group."

Source:  Twitter blog, 5th February 2014