Viva Brighton Issue #60 February 2018

INTERVIEW
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Reality check
The ‘Hallucination Machine’
Ever had a hallucination?
Did you know that you’re
having one right now?
Our grip on reality is,
according to neuroscientists,
much less tangible than we
believe. It seems our brain is
largely guessing what’s going
on around us, which it does
by combining input from our
senses with our expectations
developed from previous experiences.
In fact, as University of Sussex neuroscientist
Professor Anil Seth points out in his 2017 TED
talk: “It’s only when we agree about our hallucinations
that we call it reality.”
Such fascinating mysteries of the mind-brain are
the focus of research at the university’s Sackler
Centre for Consciousness Science, of which Seth
is a director.
As part of the Brighton Science Festival this
month, two of the centre’s researchers, Dr David
Schwartzman and Dr Keisuke Suzuki, will be
demonstrating research straight out of the lab
that both confirms and confounds our notions of
what is – and isn’t – real.
Being Somebody will showcase interactive virtual
reality (VR) that explores how our experiences
of the world are shaped by our bodies and how
bodily experience itself is actively constructed,
moment-to-moment, by the brain. For example,
they will show how easy it is for us to be momentarily
fooled into believing that a fake limb, or
even a fake body, could be part of ourselves.
They will also give visitors a simulated taste of
the trippy world of visual hallucinations.
While in normal life the balance between the
brain’s expectations and sensory input works
just fine, in some altered states – for example
brought on through
psychoactive drugs, or by
mental disorders such as
schizophrenia – perceptual
hallucinations
can become strange and
disturbing.
To explore how and why
these unusual hallucinations
occur, Suzuki and
Schwartzman have combined
Google’s Deep Dream algorithm, which
is an artificial neural network that finds and enhances
patterns in images, together with a virtual
reality headset with 360-degree panoramic video
of pre-recorded natural scenes, to create what
they are calling the ‘Hallucination Machine’.
The setup simulates the visual hallucinatory
aspects of a psychedelic trip. Anyone who puts on
the headset is soon experiencing a weird world in
which vivid hallucinations of dogs, cars and peacocks
appear in the sky, on buildings, on humans
– in fact, all over the panoramic view.
This is because the system was trained to categorise
a thousand different types of images. The
network looks for patterns that might resemble
a dog within the image – in the same way that
humans see faces and other images in meaningless
patterns, such as clouds.
Suzuki points out: “This is purely an engineering
system. It’s not really modelling the brain, but
there are a lot of similarities between the human
visual system and this neural network.”
Importantly, the research may help clinicians to
understand what’s happening in a neurophysiological
sense during hallucinatory episodes.
Jacqui Bealing
Sallis Benney Theatre, 17th February, part of the
Brighton Science Festival. brightonscience.com
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