Christopher Deason stumbled upon the psychological questionnaire on June 9, 2014. He was taking a lot of online surveys back then, each one earning him a few dollars to help pay the bills. Nothing about this one, which he saw on an online job platform, struck him as “creepy or weird,” he said later.
So at 6:37 that evening, Mr. Deason completed the first step of the survey: He granted access to his Facebook account.
Less than a second later, a Facebook app had harvested not only Mr. Deason’s profile data, but also data from the profiles of 205 of his Facebook friends. Their names, birth dates and location data, as well as lists of every Facebook page they had ever liked, were downloaded — without their knowledge or express consent — before Mr. Deason could even begin reading the first survey question.
The information was added to a huge database being compiled for Cambridge Analytica, the political data firm with links to Donald J. Trump’s 2016 presidential campaign. None of the people whose data was collected knew it had happened, not even Mr. Deason. “I don’t think I would have gone forward with it if I had,” Mr. Deason, 27, said in a recent interview.
