Anomalies of the Familiar

silhouetteToday we explore one of the strangest corners of abnormal psychology: delusional misidentification syndromes. In Who Was Martin Guerre, we learned that the process of recognition of identity is a delicate one. And that’s when all involved parties are healthy! Certain neurological disorders make recognition of identity a much more difficult prospect, and the consequences are quite bizarre.


Though not actually a delusional misidentification syndrome, we should begin with prosopagnosia: the inability to recognize all faces. Note that the vision of prosopagnosics is completely unaffected; they may have 20/20 eyesight. It’s the ability to recognize faces in particular that’s impaired. This is possible because vision in general is processed in the lateral geniculate nucleus and in the visual cortices. Faces, on the other hand, are processed in an entirely different area: the fusiform gyrus, also known as the fusiform face area.

Prosopagnosia is fairly common. It may result from brain damage (acquired) or it may exist from birth (congenital); in fact, about 2.5% of the population suffers from congenital prosopagnosia. Prosopagnosics aren’t entirely without hope. They often assess identity by assembling facial features “piecemeal” (full lips, pronounced cheekbones, green eyes, brown hair; looks like Mary). Further, they use clues like clothing, gait, and voice; note that ability to recognize identity from voice is generally unaffected. Still, prosopagnosics often report difficulty with social interaction in general, since the inability to tie face to identity makes it difficult to keep track of relationships.

Interestingly, prosopagnosics also tend to suffer from topographical disorientation, a characterized by an inability to become familiar with one’s environment and to use landmarks. So, maybe the fusiform face area isn’t just for faces. Perhaps it coordinates the general ability to tie several components together and instantly recognize the whole.

Now, for the misidentification syndromes:

Capgras Syndrome

A student at UCSD was injured in a car crash; he spent a few weeks in a coma. Upon waking, he seemed to be doing fine, except for one strange detail: when his mother visited him at the hospital, he swore she was an impostor! “She looks just like my mother,” he admitted, “but she’s just not my mother. Something’s not right.” He thought the same of his dad and of all his other friends and family; they had all been replaced by doubles.

What happened here? Well, his ability to recognize faces was fine (note that Capgras Syndrome does not represent acquired prosopagnosia), as was his ability to feel emotion. But the connection between these two respective brain areas—the fusiform gyrus and the amygdala—was severed. Before the accident, he’d recognize his mom’s face, feel the emotional connection he was used to feeling when he saw her, and go on with his day. Now, though, he’d see his mom, but not feel the customary emotional response. Thus his only possible conclusion was that she wasn’t his mom in the first place. As Carol Berman, psychiatrist at the New York University Medical Center, describes the delusion: when the patient views a person, “it’s as if the soul of the person isn’t there” (1).

To provide confirmation for the aforementioned theory: when the student talked to his mom or dad on the phone, he was fully convinced it was them! Thus, only the route between vision and emotion was damaged.

Capgras syndrome can result from brain trauma, as in this case, but more often, it comes along with schizophrenia.

Fregoli Syndrome

Fregoli syndrome, or the delusion of doubles, is the belief that several people within one’s life are actually all the same person, assuming multiple identities via disguise. Even multiple objects, places and events can seem to the observer to be one and the same!

Fregoli syndrome, like Capgras, often comes with schizophrenia. Also, like Capgras, it can be induced by traumatic brain injury. Distinct form Capgras syndrome, though, is the fact that Fregoli syndrome can result from damage to the fusiform gyrus. It makes sense: in Capgras, the ability to recognize faces is fine; only the emotional response is impaired. In Fregoli, though, the fusiform gyrus might have a lower threshold for recognition. Thus it sends the “recognition” signal to the amygdala even if the recognized face does not belong to the usual producer of that emotional response. To the observer, multiple faces produce the emotional response usually reserved for just one, and so all of those people seem to be the same.

Shockingly, antiparkinsonian medication is also one of the leading causes of Fregoli syndrome!

Also interesting is that, especially in cases of Fregoli syndrome alongside schizophrenia, the delusions are often persecutory in nature. In other words, one master of disguise is using his false identities to chase the observer. Finally, especially in schizophrenics, Fregoli syndrome is sometimes seen together with Capgras. Imagine the horror!


People in the observer’s environment swap identities and/or appearances. One woman, suffering from bipolar disorder and depression, said that her abusive husband was using his powers of intermetamorphosis to “play tricks on [her] mind” and manipulate her. Both of her parents had been dead for 10 years, but her husband would regularly change into her father, or her mother, or even both at the same time. “He dresses up like them, changes his face and voice, and tries to tell me what to do,” she said. No other psychotic symptoms were found; she was not schizophrenic (2). One of the very few possible explanations was that the woman underwent several cingulotomies in order to treat her depression. However, cingulotomy offers a brief recovery period and has not been known to produce neuropsychological side effects. How incredibly bizarre.

I’ve mentioned only a few delusional misidentification syndromes; there are many more (see source 3). They only get stranger from here, and often, patients combine symptoms from several. Misidentification syndromes can be quite difficult to classify. Some scientists, though, claim a single common element: anomalies of familiarity. In pretty much any misidentification syndrome, including the ones described here, patients don’t feel familiarity when they should, or feel familiarity when they shouldn’t.

In fact, I think there’s a misidentification syndrome we’ve all experienced at least once: déjà vu. You think that you haven’t been here before. Yet, somehow, you feel that you have. You feel familiarity when you shouldn’t.

Misidentification isn’t as rare as we think. Our grip on reality is a fragile one indeed.

References and Further Reading:

  1. Seeing Impostors: When Loved Ones Suddenly Aren’t
  2. A New Identity for Misidentification Syndromes
  3. Delusional Misidentification Syndrome
  4. Capgras Syndrome
  5. Fregoli Syndrome

7 comments on “Anomalies of the Familiar

  1. Pierce says:

    I’m not sure if you’ve read “The Man who Mistook His Wife for a Hat” by Oliver Sacks, but if you haven’t its a good read. In it there are stories of his experiences with patients who had Capgras and other similar syndromes.
    I hadn’t heard of intermetamorphosis, but it seems very intriguing, are there any other known cases of it occuring?

    • Josh says:

      I haven’t read “The Man who Mistook His Wife for a Hat,” but I’ve heard of it and really want to check it out. It sounds very interesting.

      I did some research on the book, and found some information on the case study for which it was named. It looks like the patient, P., was a music teacher who struggled to visually recognize objects. He saw a flower in Dr. Sacks’ lapel pocket, and described it as “a convoluted red form with a linear green attachment.” However, upon smelling the flower, he remarked, “It’s a rose!” Similarly, he tried to grab his wife’s head and place it on his, thinking that he was putting his hat on. Note that P.’s eyesight was fine, but he was unable to compile collections of visual stimuli into a single coherent idea.

      Dr. Sacks attributes P.’s deficit to a tumor in the visual cortex. When P. sees an image, the information is carried fine from the eye and through the optic nerve. In the brain, though, raw sensory data turns to meaning. This was the step that P. was unable to perform. So, while interesting, I wouldn’t attribute P.’s symptoms to a misidentification syndrome in the proper sense. Instead, his case is one of extreme visual agnosia, which is like prosopagnosia, but regards everything, not just faces (note that faces were just one of the many things P. had trouble recognizing). In the cases of misidentification syndroms (and in contrast to P.), the link between low-level visual processing and the visual cortex is fine. The link that’s damaged, instead, is that between the visual cortex and the amygdala, the brain’s center for emotion.

    • Josh says:

      There are a good amount of known instances of intermetamorphosis, but generally, it’s one of the rarest and most elusive misidentification syndromes. A few examples:

      A woman believed that her husband had turned into her neighbor, both in appearance and in personality. She was so sure of his transformation in appearance that she attested her husband now had a mark on his neck, which had existed only on her neighbor.

      Another woman was brought into a hospital for a psychiatric evaluation. She was suffering from symptoms of schizophrenia, which was unsurprising, since she had recently elected to discontinue her antipsychotic medication. At the end of the interview, she became suspicious, and asked, “Uncle Harry, why are you doing this? You’re supposed to be dead.” She believed that the interviewer was her late uncle Harry, both psychologically and physically.

      Source: The syndrome of Intermetamorphosis by Peter A. Bick. Contains some great information on medical history and pharmaceutical treatment of the patients.

      Note that, in both of these cases, the patient believes that those around her have transformed into someone else both in appearance and in personality. This points to a slight oversight in my post, which I was hoping someone might catch. I said that the observer might feel that people change in appearance and/or personality, but in its strictest sense, metamorphosis regards only a change in appearance and personality.

      In the case study I mentioned in my post, the woman believed that her husband changed into her parents, but in appearance only! Psychologically, the people berating her, who looked like her parents, were still her husband. Now, this case is starting to sound almost like Fregoli syndrome! After all, one person takes up the appearance of several other people for the purpose of persecution. However, Fregoli doesn’t quite fit the bill either. In Fregoli syndrome, the patient sees person A, and due to his or her delusion, mistakenly believes that A is is in fact B in disguise. In this case, though, the patient sees B, and mistakenly believes that B is disguising himself is A. In other words, in classic Fregoli syndrome, the impersonated triggers the delusion. In this study, though, the delusion is triggered by the impersonator.

      Thus the case I mentioned in my post contains elements of both intermetamorphosis and Fregoli syndrome. This just goes to show the complex range of possible misidentification syndromes. It seems that a cleaner classification system is required to handle the diverse range of possibilities. My source # 2 proposes a new system, but I don’t think it does much to improve the confusion. I’m open to new ideas!

      • Pierce says:

        Wow that’s really amazing. Our brains are so incredibly complex and interesting!
        Thanks for the reply.

  2. Richard says:

    I find myself wondering whether any phrenology-type research has been done for déjà vu. Does it behave, neurologically, just like normal memory? I suppose it probably does, though it’s often accompanied by a feeling of surprise.

    • Josh says:

      I don’t know too much about déjà vu, but I think it’s pretty clear that it’s a neurologic phenomenon, and isn’t associated with recollection of any real memories. A few examples:

      Déjà vu is associated with epilepsy, which in turn is clearly associated with structural abnormalities of the brain.

      Déjà vu is associated with use of certain drugs or combinations of drugs.

      Anecdotal, I know, but: sometimes, when I get déjà vu, I’ll have an experience; and then feel like I remember that experience; and then feel like I remember remembering that experience; and I’ll have a chain of meta déjà vu. I clearly haven’t actually remembered remembering that experience, and so on. So that points to déjà vu being a neurological phenomenon, with no bearing in real memory. Is this what you were asking in your question?

    • Ben says:

      I experience déjà vu very rarely. Until recently I hadn’t experienced it at all; I’ve now had a minor instance or two. One thing stuck out. The salient feature of my déjà vu experiences was not the feeling of having experienced the thing before. (This, of course, is the typical characterization of déjà vu.) This condition, while necessary, was neither sufficient nor central. Rather, the key sufficient condition was a certain failure of memory which induced my not being sure whether the feeling that I had experienced the thing before was merited or delusional. The unsureness was key.

      In particular, this is strong reason to characterize déjà vu as a psychological disorder — or perhaps as a one-off malfunctioning — rather than as a normal trapping of memory, which, of course, we can expect to provide us with familiar experiences once in a while.

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