Abstract
Von Neumann's theory of measurement was tested for the crisis of realism founded on the break down of Bell's inequality. The theory asserts that contraction of a wave packet in quantum mechanics by measurement is caused by out-of-brain consciousness. Imaginary measurement was carried out for the macro-system superposing two different states. The auditory evoked potentials of the measurer were compared between the time of the realization and non-realization of the imaginary measurement. The result showed the statistically significant difference in the peak amplitudes of P300s which appear in accompaniment to discrimination tasks. The explanation of this significant difference may be difficult from the viewpoint that the consciousness of the measurer does not influence the contraction of wave packets.
