• by Laurie Sullivan  @lauriesullivan, January 25, 2012

Tablets have become the consumer's fourth screen, especially among those with smartphones. Techies with smartphones continue to use tablets at a higher rate. Those in the United States -- at 17% -- are among the highest, followed by Japan at 11%, and the United Kingdom at 10%, according to Google. The data appears to fall into line with AdWords tools allowing marketers to add WiFi ad targeting.

Google also added the ability to target by mobile operating system in AdWords.

The research -- which Google conducted in two phases during 2011, in January and February followed by September and October -- finds consumers shifting from feature phones or smartphones for Internet access. In fact, they use smartphones more than desktop or laptop computers in the U.S., UK, Germany, France, and Japan.

Germany had the biggest increase in smartphone owners using their device for daily Internet access, jumping from 39% to 49%. Japan had the highest percentage accessing the Internet daily on their smartphone, at 88%.  A little more than two-thirds of smartphone users in the U.S. -- and more than half of smartphone users in the UK -- access the mobile Internet daily.

Research firm eMarketer estimates mobile advertising spending in the U.S. reached $1.45 billion in 2011, up 89% from $769.6 billion in 2010. This year, U.S. mobile ad spending will grow 80% to $2.61 billion.

The revised U.S. mobile growth forecast of 47% to $1.8 billion in 2012 -- up from $1.2 billion last year -- reflects a stream of new market data from major advertising publishers and research firms, as well as better-than-expected performance from Google.

Google's share of overall U.S. mobile ad revenue rose 51.7%, or about $750 million, in 2011. The company isn't the only one to see success in mobile. Apple's iAd platform, an ad network, generated slightly more than $90 million in revenue last year to take a 6.4% share of overall U.S mobile ad revenue. Millennial earned $90.9 million, for a 6.3% share.

As more marketers explore and launch mobile ad campaigns based on the increased use of smartphones and tablets by consumers, do the ads impact purchases? A mobile study of 1,300 respondents conducted between Dec. 26, 2011 and Jan. 11, 2012 from digital marketing firm InsightExpress sheds light on ad recall and perception.

Men ages 18 to 29 are more likely to become aware of having seen mobile ads, are more positive toward them, and are more likely to consider them new and different compared with traditional and digital ads.

Of men who participated in the study, 32% said they use their mobile phones versus a computer Internet connection or walking into a store more often when purchasing items, versus 12% of women in the same age group. Men are more likely to search for an item on mobile. About 65% searched for a product in a nearby store using their phone.

In general, young men use mobile more for information-gathering than women. While 59% of men use their mobile phone to find better prices on items, 49% use their mobile phone to search for an item to find reviews, and  41% use their mobile phone to take a picture or send it to someone.