The Psychophysics of Death

Blackmore,S.J. and Troscianko,T.S. 1988 Perception 17 419 (abstract)

S. Blackmore and T. Troscianko (Brain and Perception Laboratory, Department of Anatomy, The Medical School, University of Bristol, University Walk, Bristol BS8 1TD, UK)

A common feature of the near-death experience (e.g. in patients suffering a cardiac arrest) is the experience of passing down a long dark tunnel with a bright light at the end. Tunnels are also reported with major hallucinogenic drugs, in migraine and epilepsy, and can be produced stroboscopically and by binocular pressure. Cowan (1982 International Journal of Quantum Chemistry 22 1059-1082) argues, in an analogy with fluid mechanics, that the tunnel is produced when cortical disinhibition destabilises the uniform state and causes stripes of activity to flow across visual cortex. By mapping this back to visual space, expanding or contracting spirals and tunnels are produced. A simpler theory is that disinhibition produces random noise in visual cortex. We argue that a display which mimics the M-scaled visual projection of the random noise elicits a strong sensation of an expanding optic flow field which is similar to ‘travelling down a tunnel’. This we demonstrate.