Consciousness-related interactions in a double-slit optical interferometer

Motivated by a series of reported experiments and their controversial results, the present work investigated if volunteers could causally affect an optical double-slit system through mental efforts alone. The participants' task alternated between intending the increase of the (real-time feedback informed) amount of light diffracted through a specific single slit and relaxing any intention effort. The 160 data sessions that 127 volunteers took part in revealed a statistically significant 4.68 sigma difference between the measurements performed in the intention versus the relax conditions ($p=2.93\times10^{-6}; \, es= 0.47 \pm 0.20$ 95\% CL), while the 160 control sessions conducted without any observers present resulted in statistically equivalent samples ($z=0.35, \, p=0.73; \, es=0.04 \pm 0.20$ 95\% CL). The results could not be explained by environmental factors, hence supporting the previously claimed existence of a not yet understood form of interaction between a conscious agent and a physical system.