Does wavefunction collapse require a conscious observer? A preregistered retrocausal interferometer test with human and artificial intelligence observers

The von Neumann–Wigner framework holds that wavefunction collapse is incomplete until a conscious observer intervenes. Wheeler argued that measurement choices can be deferred until after a photon transits the apparatus. Together, these ideas raise fundamental questions: What is an observer, and when does observation become definite? To investigate, diffraction-grating data recorded months before human observation drove an online animated candle flame across 1,000 human and 1,000 AI-agent sessions. Sessions alternated ten 30-second intention epochs (intending flame dimming) and ten relax epochs. One first-order diffraction spot drove the display; the other served as an unobserved control. Participants were blind to the control and prerecording; assignments were randomized. The observed sensor was regressed against the unobserved sensor, and slopes compared via label-swapping permutations. Of eight possible outcomes, only the human-observed-intention cell was significant after multiple-comparison correction (p = 0.00007). AI agents showed no effect. Pre- and post-preregistration windows were statistically equivalent. These results suggest an effect of human consciousness rather than hardware drift or analytical artifacts.