- seCtIon FIVe: BoRDeRLAnDs
Other common causes of hallucinations are drugs, physical illness, starvation, and
sleep deprivation, as well as ritual practices such as rhythmic drumming, whirling,
dancing, chanting, flagellation, or control of the breath. Sensory deprivation is a
powerful way to induce hallucinations. It is as though when deprived of input, our
sensory systems find patterns in what little information they have, lower their cri-
teria for what to accept as real, or turn to internally generated stimulation instead.
This is simply an intensified version of the universal human habit of pareidolia:
seeing familiar patterns on the flimsiest pretext, like turning lunar contours into
the man in the moon or hearing messages in music played backwards.
And this is if you look carefully at certain walls soiled by different
stains or at stones of uneven composition. Should you have to
invent a setting, you will be able to see in these the likeness of
different regions, embellished with mountains, rivers, rocks, trees,
wide plains, valleys and hills in different ways; moreover, you will
be able to see in them various battles and actions ready to be
performed, involving strange figures, outlines of faces and clothes
and endless things, which you can reduce to complete and proper
shapes; in such walls or stones the same happens as with the
sound of bells, in whose strokes you will find any
name or word you can imagine.(Leonardo da Vinci, A Treatise on Painting [Trattato della pittura],
1651, our translation)In the 1930s, British neurologist Hughlings Jackson suggested
the ‘perceptual release’ theory of hallucinations: that memories
and internally generated images are normally inhibited by input
from the senses, and are released when that input is disrupted
or absent. Louis West (1962) developed this theory, suggesting
that hallucinations occur when there is both impaired sensory
input and sufficient arousal to permit awareness. American psy-
chologist Ronald Siegel (1977) likens this to a man looking out of
the window near sunset. At first, all he sees is the world outside.
Then, as darkness falls, the reflection of the fire inside and the
room it illuminates take over, and now he sees them as though
they lie outside. In this way, ‘inner’ images come to seem real.
The implication here is that either the outside or the inside of
the room takes over as the current model of reality; the two
compete and both cannot seem real at once. This idea has been
applied to some sleep-related phenomena and to out-of-body
experiences in which a completely hallucinated world takes
over from the perceived world and becomes the current model
of reality (Blackmore, 2009, 2017; Metzinger 2009). Something
like this happens to people who immerse themselves in sensory
deprivation tanks, floating in warm water in complete darkness
and silence. In this situation, there is no reliable sensory input
and so the self-generated world is the only reality available.PRoFILe 14.1
Ronald K. Siegel (b. 1943)
Ronald Siegel is a pioneer of
drug studies and explorer of
altered states of consciousness.
In the 1970s, he and his col-
leagues trained people to be-
come ‘psychonauts’ – that is,to go into altered states and report what they experienced
as it happened. He has researched the effects of LSD,
THC, marijuana, MDMA, mescaline, psilocybin, and ket-
amine, among other drugs, and has acted as consultant
on several investigations of drug use. He is not just an ex-
perimenter and theoretician of psychopharmacology, but
has trained in martial arts, experienced sleep paralysis,
taken part in shamanic rituals, and was once locked in a
cage for more than three days without food or water, all
in the interests of investigating consciousness. He has a
PhD in psychology from Dalhousie University and is au-
thor of many books on drugs, hallucinations, intoxication,
and paranoia.