US consumers are some of the biggest users of smartphone and tablet devices in the world, so why is their response to mobile ads so poor? According to Q3 2011 research from Nielsen, smartphone and tablet users in Germany, Italy and the UK responded more favorably to mobile ads than US device owners did. With smartphone ads, in particular, users in Germany, Italy and the UK were significantly more likely than users in the US to take actions - click on ads, conduct research or make purchases.