This article tells the story of an anthropologist and a research subject who encountered each other in the middle of the 20th century on an island in the southwestern Pacific. In the midst of an intensive spate of evidence gathering for his dissertation, anthropologist Melford Spiro noted that one of his would-be interlocutors, a man named Tarev – notable for failing all of his psychological tests – still managed to contribute a different form of evidence: if his views could not (...) be amalgamated in numbers via test scores, they could still be rendered as a case. Tarev’s personality study, ‘A Psychotic in the South Seas’, counted as one of many cases contributing to a broad, worldwide effort to explore the meaning of suffering – specifically psychological illnesses – in non-Western cultures. This article examines Tarev’s rejected test-response ‘data’ and the ways in which his answers did not fit the epistemological and geopolitical frameworks that provoked them. The encounter between anthropologist and interlocutor, today, allows an investigation into how mid-20th-century scholars amassed ambitious data sets meant to revolutionize the sciences that dealt with human beings as psycho-social entities. What sorts of data made it into their archives and what sorts did not? How was the data of happiness, sadness and other fleeting emotional states collected from whole islands newly under US naval occupation? (shrink)