I had Opus 5.5, Fable 5.1 and Sonnet 5.5 take two real personality tests

A user conducted an experiment where Opus 5.5, Fable 5.1, and Sonnet 5.5 took two real personality tests. Each AI model completed both tests 10 times, consistently providing identical answers for 78-85% of the 280 statements. This experiment was inspired by a colleague's suggestion to give Claude a Myers-Briggs test, though the user opted for more accepted personality assessments.

Unlike typical anecdotal AI personality assessments, this report details a structured experiment where three Claude models took two tests 10 times each, revealing high consistency.