An article at Ars summarizes a study into how simply seeing pictures can alter what we believe, even if the pictures don't provide any information about the topic at hand (abstract). Researchers asked true-or-false questions to a group of test subjects about whether a minor celebrity was still alive. When they provided a picture of the celebrity, more people evaluated the statement as 'true' than when no picture was provided. The researchers then switched the question, asking whether it was true or false that the celebrity was dead. Again, the subjects shown a picture were more likely to respond with 'true.' Experiments also showed this phenomenon wasn't limited to questions about people, but general knowledge as well. "The authors spend a bit of time discussing why this sort of truth bias might arise. In cases where we have rich information—a photo or detailed description of something—it's easier to pull additional information out of our memory. So, even if a photo doesn't tell us much about whether the person is alive, it does make it easier to retrieve relevant information on them—if they're wearing a suit in the photo, we might reason they're a political or financial figure, etc. When the information flows that readily, we're more likely to conclude that we're familiar with the question that's being posed, and will then tend to conclude it's true."