When Joseph looked in the mirror, he saw a man he had never seen before. He pinched himself. The man in the mirror pinched himself. But it still wasn’t Joseph.

“Do I look different?” he asked people. “Am I still the same person?”

Rosamond, from Queens, N.Y., also was having trouble with the image she saw in the mirror.

But she believed the woman whose reflection she encountered was there to torment her, to steal her husband. Rosamond called her a “hussy” and went into hysterics whenever she saw her.

Rosamond’s husband finally covered up all the shiny surfaces in the house to prevent her outbursts, but he was afraid she would hurt herself in an effort to attack the “other woman.” And there was no way he could cover every reflective surface.

Joseph and Rosamond, whose real names are not being used, are two of a rare group of patients whose mental illnesses involve the parts of the brain that allow us to know we are who we think we are. Their strange disorders demonstrate that it’s not enough for us to recognize ourselves in a mirror — we have to feel emotionally attached to our image before we think it is our own reflection.

The technical name for Joseph’s and Rosamond’s delusion is “mirror self-misidentification.” It is the most striking of the Capgras delusions, in which someone recognizes an object but feels no connection with it.

The syndrome, named for French psychiatrist Jean Marie Joseph Capgras, is unusual, but still probably afflicts thousands of people in the United States at any given moment, said Dr. Todd Feinberg, associate professor of neurology and psychiatry at the Albert Einstein College of Medicine in New York.

Broken link

Joseph’s psychiatrist, Dr. Matcheri Keshavan, clinical director at the Pittsburgh Center for the Neuroscience of Mental Disorders, said the delusion can also involve another person in the patient’s life. “The main illusion (Capgras) patients have is that a dear one is an impostor, or not their real self.”

Keshavan explained the underpinnings of the delusion this way:

“We all have representations of the external world inside us, and that includes identities of other people and our own identities. Along with these representations of other people and ourselves, the emotional tone that goes with such memories is also linked, so when we remember our mothers or friends we remember them with the emotions that go with them.

“But what if there is a dysfunction in parts of the brain that link emotions with our memories? When that happens, the brain at the subconscious level is puzzled and looks for an alternative explanation of why that person feels different.”

And suddenly the person in the mirror becomes someone else, because when the deluded person cannot feel the emotions she normally has toward that person, that is the explanation that makes the most sense.

Not all Capgras delusions are focused on people. Sometimes, patients think there is something wrong with their pets or objects they own — and in those cases, the same sense of emotional dissociation may be at work.

Keshavan said that when people have an emotional reaction to someone they know, they sweat slightly, making the skin more conductive. That can be measured as a galvanic skin response.

But when Capgras patients see certain familiar faces, their galvanic response does not increase, he said.

Constantly shifting identities

Feinberg believes there is more to understanding Capgras than just the emotional disconnection with a familiar person or object, however.

Rosamond, his patient who thought her own image was another woman, didn’t have a problem identifying anyone but herself. She properly identified her husband and the things around her, he said. The emotional disconnection theory doesn’t completely explain why Rosamond reacted as strongly as she did to her image.

“Why would she scream and yell and become so emotionally upset?” he asked.

One possible reason, Feinberg said, is that people with Capgras already have ambivalent or strained feelings toward the person they misidentify — including themselves.

Is the delusion curable?

In both Joseph’s and Rosamond’s cases, it was — but in different ways.

Joseph was eventually diagnosed as having schizophrenia, Keshavan said. When he was prescribed the anti-psychotic clozapine, his delusion went away.

Rosamond was cured because Feinberg tried a novel therapy on her. “Rosamond’s husband casually mentioned that she didn’t see (the other woman) when she looked in the mirror of her makeup compact,” he said.

That gave him a brainstorm — why not try to have her look at images of herself in increasingly larger mirrors?

“I went around the office — we had other mirrors of different sizes — and went out and bought a series of mirrors,” he said. “I was ultimately able to convince her that an image of slightly larger size was her.”

Eventually, Rosamond recognized that her reflection in a full-sized mirror was indeed herself.

What lessons do Joseph’s and Rosamond’s experiences hold for us? One conclusion, Feinberg said, is that our identities are not as rigid and fixed as we might imagine.

“Although we tend to think of ourselves as having fixed structures — we know where our body begins and ends and we have a sense of who we are in the world — in actuality,” he said, “our identity is in a constant state of transformation and is always changing.”