Google’s search algorithm can easily shift the voting preferences of undecided voters by 20 percent or more—up to 80 percent in some demographic groups—with virtually no one knowing they are being manipulated, according to experiments I conducted recently with Ronald E. Robertson.
In laboratory and online experiments conducted in the United States, we were able to boost the proportion of people who favored any candidate by between 37 and 63 percent after just one search session.
Source: How Google Could Rig the 2016 Election – POLITICO Magazine