science

Prosopometamorphopsia

Prosopometamorphopsia is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Prosopometamorphopsia rather than just read about it. In short: Prosopometamorphopsia (PMO), also known as demon face syndrome, is a neurological disorder characterized by altered perceptions of faces. In the perception of a person with the disorder, facial features are distorted in a variety of ways including drooping, swelling, discoloration, and shifts of position.

Key takeaways

Prosopometamorphopsia belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Prosopometamorphopsia to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Prosopometamorphopsia from memory before moving on to harder problems.

Reference excerpt

Prosopometamorphopsia (PMO), also known as demon face syndrome, is a neurological disorder characterized by altered perceptions of faces. In the perception of a person with the disorder, facial features are distorted in a variety of ways including drooping, swelling, discoloration, and shifts of position. Prosopometamorphopsia is distinct from prosopagnosia, which is characterised by the inability to recognise faces. About 75-81 cases of prosopometamorphopsia have been reported in scientific literature since 1904. In about half of the reported cases, features on both sides of the face appear distorted. In the other half of the cases, distortions are restricted to one side of the face (left or right), called hemi-prosopometamorphopsia.

Signs and symptoms Faces tend to appear distorted to a person who is affected by prosopometamorphopsia. Those who suffer from this condition are able to recognize faces normally but perceive them as strangely disfigured. These facial hallucinations are usually described as ugly, and have prominent eyes and teeth. Some have described the faces as having a cartoon-like quality. Faces have been known to be perceived as contorted and as having displaced features. For example, one patient described a person's face as having a nose deviated to the side, the mouth lying at a diagonal and one eyebrow being higher than the other. Prosopometamorphopsia may either involve perceptions of the whole face or only one side of the face (usually after right hemisphere damage).

Causes The definitive cause for prosopometamorphopsia is still unknown. However, several potential theories have been expressed in the literature in this area. This condition has been associated with damage or abnormalities in various brain areas (i.e., temporal, occipital, parietal, and frontal lobes). The development of prosopometamorphopsia has been recorded to be a manifestation of epilepsy in some cases. Functional imaging studies in humans have identified an area in the fusiform gyrus which is selectively activated by stimulation when exposed to faces called the fusiform face area (FFA). Another area known to be activated by face stimuli is the superior temporal sulcus (STS). This region is particularly active when having to process facial expressions, especially the expressive features related to the eyes. Therefore, it has been suggested that the prominent eyes (which is a typical feature in the facial perceptions) in the distortions recorded is more in accordance with increased activity (which would cause an overrepresentation of the eyes) within the STS rather than the fusiform face area. Other studies, however, have found that stimulation of the posterior and mid-fusiform face selective regions in a patient with medication-resistant epilepsy resulted in perceptions consistent with that of facial metamorphoses (patient noted that the experimenter's face started to droop). This study found that the perceived distortions correlated with signal changes in the patient's FFA, and not in the STS.

Diagnosis

Classification Prosopometamorphopsia is considered a face hallucination and is included under the umbrella of complex visual hallucinations. Unlike other forms of hallucinations such as peduncular hallucinosis or Charles Bonnet syndrome, prosopometamorphopsia does not predominate at a particular time of day; it is a constant experience. However, patients with Charles Bonnet syndrome have noted descriptions of prosopometamorphopsia. This form of perceptual distortion along with others such as macropsia and micropsia (alteration of perceived object size) and palinopsia (spatial and temporal varieties and polyopia) are classified under the category termed metamorphopsia. These facial distortions can occur to either hallucinated perceptions or true (non-hallucinated) perceptions. It is attributed to structural brain changes or functional disorders like epilepsy, migraine or eye diseases. There are four recognised types of prosopometamorphopsia.

Autoprosopometamorphopsia - At least some portion of the patient's own face is distorted. Heteroprosopometamorphopsia - A significant amount of faces other than the patient's own face is distorted. Hemiprosopometamorphopsia - Right or left half of faces appear distorted. Zoanthroprosopometamorphopsia - Faces appear to distort into that of animals.

Treatment Antidepressants such as citalopram and the antipsychotic quetiapine have been recorded as unable to facilitate improvements for these symptoms. Valproic acid was initially used to treat a woman who hallucinated dragon-like faces and this alleviated her symptoms entirely, however, she went on to develop auditory hallucinations as a side effect. She was subsequently prescribed rivastigmine instead which reduced the auditory hallucinations and reduced her visual symptoms. The 75-year-old woman in the previous study was treated with intravenous heparin infusion and coumadization over a period of 10 days which enabled the alleviation of her visual symptoms almost entirely. The type of treatment may vary depending on the cause of the facial distortions.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Prosopometamorphopsia

Start with the simplest possible case. Write down what Prosopometamorphopsia claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Prosopometamorphopsia before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Prosopometamorphopsia ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Prosopometamorphopsia

In research: Prosopometamorphopsia appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Prosopometamorphopsia in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Prosopometamorphopsia is common in secondary-school and first-year university syllabi. It links to neighbouring topics Facial recognition, Hallucinations, Visual disturbances and blindness, so understanding it makes those chapters shorter.
In everyday life: Look for Prosopometamorphopsia outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Prosopometamorphopsia in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Prosopometamorphopsia means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Prosopometamorphopsia out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Prosopometamorphopsia in simple terms?

Why does Prosopometamorphopsia matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Prosopometamorphopsia?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Prosopometamorphopsia.