Via Girl From The North Country, a thoroughly distressing article about the intersection of big data, shadowy companies and mainstream politics...

Facebook was the source of the psychological insights that enabled Cambridge Analytica to target individuals. It was also the mechanism that enabled them to be delivered on a large scale.

The company also (perfectly legally) bought consumer datasets – on everything from magazine subscriptions to airline travel – and uniquely it appended these with the psych data to voter files. It matched all this information to people’s addresses, their phone numbers and often their email addresses. “The goal is to capture every single aspect of every voter’s information environment,” said David. “And the personality data enabled Cambridge Analytica to craft individual messages.”

Finding “persuadable” voters is key for any campaign and with its treasure trove of data, Cambridge Analytica could target people high in neuroticism, for example, with images of immigrants “swamping” the country. The key is finding emotional triggers for each individual voter.

Cambridge Analytica worked on campaigns in several key states for a Republican political action committee. Its key objective, according to a memo the Observer has seen, was “voter disengagement” and “to persuade Democrat voters to stay at home”: a profoundly disquieting tactic. It has previously been claimed that suppression tactics were used in the campaign, but this document provides the first actual evidence.