In the classic 1956 film Invasion of the Body Snatchers, the
residents of a fictional town in California are beset by the feeling
that their friends and family have been replaced by impostors. In
the movie, this apparent delusion is not delusional at all: The
townspeople are in fact being replaced — by aliens, no less.
Numerous sci-fi films since have capitalized on our fear of being
surrounded by duplicates — replicas who look just like our loved
ones but are not. And while there have so far been no confirmed
cases of a human being replaced by an alien or any other life-form,
the feeling that your loved one has been replaced by someone else
can be very real.
Consider these two true stories:
A 37-year-old woman came into the office of Carol Berman, a
psychiatrist at New York University Medical Center, with a strange
complaint. She had returned to her house recently to find a man
sitting on her couch. He was familiar, sort of, and he was wearing
her husband's clothes. But something didn't feel right to this
woman. She felt a strange kind of emptiness when she looked at him.
She was struck by the very deep sense that her husband had somehow
been replaced by this strange man.
A student at the University of California, San Diego was severely
injured in a car accident. After several weeks in a coma, he
regained consciousness and seemed to be doing fine. But according to
V.S. Ramachandran, a neuroscientist at the university, when the
patient's mother came to see him, he exclaimed, "Who is this woman?
She looks just like my mother, but she's an impostor! She's some
other woman pretending to be my mother."
Rare Delusional Disorder
Both patients, it turns out, were suffering from a rare delusional
disorder, called Capgras. Capgras delusion can be brought about by a
variety of conditions — changes in brain chemistry associated with
different mental illnesses, or physical trauma to the brain — but
the delusion always involves the distinct feeling that the people
around you have been replaced by impostors. While they may look and
act just like the real person, some essence of the person is
missing, almost as though "the soul of the person isn't in there,"
Berman says.
Currently, no one is certain of the underlying cause of Capgras, and
there are different ways of explaining what is happening to these
people. According to Berman, Capgras might be caused by
psychological dissonance. There are usually things about the people
close to us that we don't like. Normally, we combine these things
with the parts we do like and develop a general emotional response
to the whole person. But in some extreme cases, a change in
character or a newly noticed behavior can just be too difficult to
accept, to integrate into the whole. And so, rather than reframing
our sense of who that person is, our brain just says: "That must not
really be him."
Ramachandran thinks that Capgras can be better explained by a
structural problem in the brain. According to Ramachandran, when we
see someone we know, a part of our brain called the fusiform gyrus
identifies the face: "That looks like mom!" That message is then
sent to the amygdala, the part of our brains that activates the
emotions we associate with that person. In patients experiencing
Capgras, Ramachandran says, the connection between visual
recognition and emotional recognition is severed. Thus the patient
is left with a convincing face — "That looks like mom!" — but none
of the accompanying feelings about his mother.
That's Not My Mother
Ramachandran holds that we are so dependent on our emotional
reactions to the world around us, that the emotional feeling "that's
not my mother" wins out over the visual perception that it is. The
compromise worked out by the brain is that your mother was somehow
replaced, and this impostor is part of a malevolent scheme.
Ramachandran thinks there's good evidence for this explanation of
Capgras, in part because of an odd quirk in his patient's behavior.
When his mother calls him on the phone and he hears her voice, he
instantly recognizes her. Yet if she walks in the room after that
call, he is again convinced that she is an impostor.
Why? Ramachandran says that our visual system and auditory system
have different connections to the amygdala, so while the auditory
recognition triggers an emotional response in his patient, visual
recognition does not.
Treating The Illness
Capgras is very rare, and little is known about how to treat it.
Those who have been afflicted with Capgras due to physical brain
trauma may eventually re-establish the connection between perception
and emotion. (Ramachandran's patient, for example, eventually
recovered from his delusion.) And patients who experience Capgras
alongside other mental disorders may be helped by medication. But
for many Capgras patients, there is no treatment, and no amount of
talk or reasoning can cure them.
While the feeling that the people around you have been replaced by
impostors is certainly terrifying to imagine, the effect on the
supposed impostor can be devastating, too. Carol Berman's husband
began suffering Capgras after the onset of a particular kind of
dementia in which neural transmission between different parts of the
brain decays. Some days he knows that Berman is his wife. But other
days, the woman who walks through the door is an impostor.
"I hope he's recognizing me," says Berman, "but you never know what
you're going to get when you get back home."
Produced by Soren Wheeler
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