Radin, Dean; Michel, Leena; Delorme, Arnaud. (2016) Psychophysical modulation of fringe visibility in a distant double-slit optical system. Physics Essays Publication, 29(1), 14-22(9).
To investigate von Neumann’s proposal that an “extra-physical process” is involved in the measurement of a quantum system, an online experiment was conducted using a double-slit optical system. In a counterbalanced fashion, participants focused their attention toward or away from a feedback signal linked in real-time to the double-slit component of an interference pattern. A line camera continuously recorded the interference pattern at 4 Hz, and for each camera image fringe visibility was determined for the central 20 fringes. During 2013 and 2014, a total of 1,479 people from 77 countries contributed 2,985 test sessions. Over the same period 5,738 sessions were run as controls by a computer programmed to simulate human participants. The results showed that with human observers the fringe visibility at the center of the interference pattern deviated from a null effect by 5.72 sigma (p = 1.05×10-8), with the direction of the deviation conforming to the observers’ intentions. The same analysis applied to the control data resulted in an overall deviation of -0.17 sigma. After consideration of alternative explanations, these results were found to support von Neumann’s conclusion that the mind of the observer is an inextricable part of the measurement process. This type of experiment offers a means of empirically resolving longstanding questions about the role of consciousness in the physical world.