Today.Az » Weird / Interesting » What cause that feeling of being watched?
23 May 2017 [15:30] - Today.Az
By Tom Stafford
You feel somebody is looking at you, but you don’t know why.
The explanation lies in some intriguing neuroscience and the study of a strange
form of brain injury.
Something makes you turn and see someone watching you.
Perhaps on a busy train, or at night, or when you’re strolling through the
park. How did you know you were being watched? It can feel like an intuition
which is separate from your senses, but really it demonstrates that your senses
– particularly vision – can work in mysterious ways.
Intuitively, many of us might imagine that when you look at
something with your eyes, signals travel to your visual cortex and then you
have the conscious experience of seeing it, but the reality is far weirder.
Once information leaves our eyes it travels to at least 10
distinct brain areas, each with their own specialised functions. Many of us
have heard of the visual cortex, a large region at the back of the brain which
gets most attention from neuroscientists. The visual cortex supports our conscious
vision, processing colour and fine detail to help produce the rich impression
of the world we enjoy. But other parts of our brain are also processing
different pieces of information, and these can be working away even when we
don't – or can't – consciously perceive something.
The survivors of neural injury can cast some light on these
mechanisms. When an accident damages the visual cortex, your vision is
affected. If you lose all of your visual cortex you will lose all conscious
vision, becoming what neurologists call 'cortically blind'. But, unlike if you
lose your eyes, cortically blind is only mostly blind – the non-cortical visual
areas can still operate. Although you can't have the subjective impression of
seeing anything without a visual cortex, you can respond to things captured by
your eyes that are processed by these other brain areas.
In 1974 a researcher called Larry Weiskrantz coined the term
'blindsight' for the phenomenon of patients who were still able to respond to
visual stimuli despite losing all conscious vision due to destruction of the
visual cortex. Patients like this can’t read or watch films or anything
requiring processing of detail, but they are – if asked to guess – able to
locate bright lights in front of them better than mere chance. Although they
don’t feel like they can see anything, their 'guesses' have a surprising
accuracy. Other visual brain areas are able to detect the light and provide
information on the location, despite the lack of a visual cortex. Other studies
show that people with this condition can detect emotions on faces and looming
Blindsight: The strangest form
The woman with a strange ‘second sight’
More recently, a dramatic study with a blindsight patient
has shown how we might be able feel that we are being looked at, without even
consciously seeing the watchers' face. Alan J Pegna at Geneva University Hospital, Switzerland,
and team worked with a man called TD (patients are always referred to by
initials only in scientific studies, to preserve anonymity). TD is a doctor who
suffered a stroke which destroyed his visual cortex, leaving him cortically
People with this condition are rare, so TD has taken part in
a string of studies to investigate exactly what someone can and can't do
without a visual cortex. The study involved looking at pictures of faces which
had their eyes directed forward, looking directly at the viewer, or which had
their eyes averted to the side, looking away from the viewer. TD did this task
in an fMRI scanner which measured brain activity during the task, and also
tried to guess which kind of face he was seeing. Obviously for anyone with
normal vision, this task would be trivial – you would have a clear conscious
visual impression of the face you were looking at at any one time, but recall
that TD has no conscious visual impression. He feels blind.
The scanning results showed that our brains can be sensitive
to what our conscious awareness isn't. An area called the amygdala, thought to
be responsible for processing emotions and information about faces, was more
active when TD was looking at the faces with direct, rather than averted, gaze.
When TD was being watched, his amygdala responded, even though he didn't know
it. (Interestingly, TD's guesses as to where he was being watched weren't above
chance, and the researchers put this down to his reluctance to guess.)
Cortical, conscious vision, is still king. If you want to
recognise individuals, watch films or read articles like this you are relying on
your visual cortex. But research like this shows that certain functions are
simpler and maybe more fundamental to survival, and exist separately from our
conscious visual awareness.
Specifically, this study showed that we can detect that
people are looking at us within our field of view – perhaps in the corner of
our eye – even if we haven’t consciously noticed. It shows the brain basis for
that subtle feeling that tells us we are being watched.
So when you’re walking that dark road and turn and notice
someone standing there, or look up on the train to see someone staring at you,
it may be your nonconscious visual system monitoring your environment while
you’re conscious attention was on something else. It may not be supernatural,
but it certainly shows the brain works in mysterious ways.
Photo Credit: iStock