Kogan developed Kosinksi’s ideas, improved them, and cut a deal with Cambridge Analytica. Armed with this bounty – and combined with additional data gleaned from elsewhere – Cambridge Analytica built personality profiles for more than 100m registered US voters. It’s claimed the company then used these profiles for targeted advertising.
Imagine for example that you could identify a segment of voters that is high in conscientiousness and neuroticism, and another segment that is high in extroversion but low in openness. Clearly, people in each segment would respond differently to the same political ad. But on Facebook they do not need to see the same ad at all – each will see an individually tailored ad designed to elicit the desired response, whether that is voting for a candidate, not voting for a candidate, or donating funds.
Cambridge Analytica worked hard to develop dozens of ad variations on different political themes such as immigration, the economy and gun rights, all tailored to different personality profiles. There is no evidence at all that Clinton’s election machine had the same ability.