While plenty of consumers make purchases using smartphones and tablets, very few do so immediately after seeing a TV ad, says research firm Interpret LLC. This gap represents an opportunity for marketers, especially given the close links in consumer behavior surrounding tablets and TV.

Some things just don't go together. Cookies and mustard, for instance. Minivans and coolness, for another. Add Apple TV and Hulu Plus to the list as well.

Tablets and TVs go hand in hand, but in ways that may surprise marketers and networks. Tablet owners are twice as likely as smartphone owners to watch full episodes of TV shows and they spend 50% more time viewing during an average session - 36 minutes on tablets compared to 24 minutes on smartphones, according to a just-released study from research firm GfK Media comparing tablet and smartphone usage.