Prosopagnosia: The Unrecognizable Face



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Prosopagnosia



Prosopagnosia:

The Unrecognizable Face

Kristina Martinez: (007324952)

Soutsada Ieng:

Maritza Fernandez:

Camille Gener:

Nancy Serrano:

California State University of Long Beach



Abstract

Prosopagnosia was first diagnosed in 1947 by Joachim Bodamer. It is described as the impaired ability to recognize faces and is often referred to as face blindness. This fairly rare disorder is usually acquired from accidents, such as a car crash, that lead to brain damage, but patients can be born with the disorder. Recent studies have shown a hereditary or genetic component for those who are born with congenial prosopagnosia (Behrmann & Avidan 2005). There have been only a few tests done on those with congenital prosopagnosia. One of the reasons for this is the lack of sufficient tests to properly diagnose the disorder. There is currently no cure for prosopagnosia, but several forms of therapy and coping mechanisms, such as learning to recognize a family member by their shoes, helps patients to get by with their everyday lives.

Prosopagnosia: The Unrecognizable Face

Introduction

For the average individual not being able to remember the face of someone you have met once before, like a distant cousin, would be moderately embarrassing, but not permanent. You could simply reacquaint your self with what the distant relative looked like and be able to spot them easily in a photo or at the next family reunion, but the same can not be said for those who suffer from prosopagnosia. Those with prosopagnosia are unable to recognize or identify the faces of friends, family, or loved ones. Even their own face staring back at them in the mirror becomes the face of a stranger. No matter how many times they see the face of a certain person they can never recognize the face. This can lead to a variety of social and relationship problems.

With a prosopagnosia patient’s inability to recognize faces, many would assume that they are also unable to read a person’s facial expressions and make judgments based on those expressions. However, recent studies have shown that while prosopagnosia patients cannot recognize the faces presented to them, they can still read how trustworthy a person is based on their facial expressions (Todorov and Duchaine, 2008). This would also show that while their facial recognition is impaired, they can still read the emotions on a person’s face. The recent use of fMRI scans enabled Gobbini and Haxby to identify which parts of the brain are responsible for the beginning stages of facial features and where the brain shows activity from there. This led them to propose a face recognition model and led to the current debate of whether a specialized neural network is responsible for face recognition or if it is just one task of a neural structure.

History

Prior research mentioned patients with problems perceiving faces after receiving damage to the brain, but Prosopagnosia wasn’t specifically named or diagnosed until 1947 by Joachim Bodamer. The two types of prosopagnosia that are diagnosed and researched are developmental/acquired prosopagnosia and congenital/hereditary prosopagnosia. The first studies done on prosopagnosia focused on deficits in visual perception as a result of brain injury mainly to the temporal or occipital lobe. Bodamer introduced Prosopagnosia by describing the cases of two soldiers from World War II who suffered severe brain damage and experienced decreased facial recognition. The first report of congenital prosopagnosia wasn’t until 1976 by McConachie. Congenital prosopagnosia is present at birth without any apparent damage or abnormalities in the brain.

There is a similar and rare psychiatric condition called Capgras delusion, where their physical capacity to recognize faces is intact, but they believe all of the people they know are replaced by strangers or identical imposters. Acquired prosopagnosia is just the opposite, their physical capacity to recognize faces is impaired but they use other ways to recognize the people around them through audio and visual cues.

It is safe to assume that most people refer to prosopagnosia as something that is rare, but it has a surprisingly high prevalence among the Caucasian population. Congenital prosopagnosia has a prevalence of around 2.5% of the Caucasian population and has around the same prevalence as dyslexia. One of the problems in the history of prosopagnosia that still exists today is that there are no specific tests available to be able to diagnose someone with prosopagnosia. Tests like the Warrington Recognition Memory for faces (RMFs) and the Bentobn Facial Recognition Test (BFRT) are not face specific enough to be able to diagnose people with prosopagnosia. People who suffer from Prosopagnosia often don’t even realize they have it. With Bodamer’s two cases, they never thought they had any problem with recognizing faces and Bodamer was only able to diagnose it through observation, questions, and tests afterward.

Gobbini and Haxby propose a face recognition model that connects functional units to different parts of the brain, with the core system having the occipital face area (OFA) in the inferior occipital lobe, the fusiform face area (FFA) in the middle fusiform gyrus, and the face area in the dosal superior temporal sulcus (STS). According to studies done with fMRI, the STS showed activity for expression, eye gaze, and facial speech, while both the OFA and FFA showed activity for facial features for identification. It was initially believed that the OFA was responsible for the beginning stages of facial features that then passed it on to the FFA and STS, but there have been cases since then that show otherwise. There is a reported case of a woman that had acquired prosopagnosia because of major tissue loss in the right inferior lateral occipital lobe and the left medial temporal lobe. Her right OFA was damaged but she was still able to use her right FFA to react to faces.

To this day, it is still being debated whether a specialized neural network is responsible for face recognition or if it is just one task of a neural structure. There was also an earlier debate whether right-sided lesions caused Prosopagnosia or whether you needed lesions in both the occipital and temporal lobes. Since then, there have been several imaging studies that show the right FFA shows a stronger activation to faces compared to the left. Both sides of the brain have the capacity to recognize faces, but studies show that the right side of the brain is responsible for face processing and damage to that area more often leads to a deficit in facial recognition. Most cases of acquired prosopagnosia are caused by strokes and accidents.



Biological

Prosopagnosia has usually been seen in individuals who obtain the disorder from neurological damage, such as from a stroke or head injury. Having this type of damage severely disrupts face recognition and can leave a person with several different types of problems. Face recognition problems can transpire in a different number of levels. One way is by having visual sensory problems such as not being able to discriminate shapes, this would mean that a person cannot perceive faces properly. A second problem is perception involving the setting of all information together into a whole. Not having the ability to do this means that a person cannot recognize an individual because even though they can see all the parts of a face they cannot see the face as a whole. Another problem is impaired recognition of individuals this is due to problems of retrieving stored memories of well-known faces. If a person cannot do this then they are not able to compare a face in front of them with a memory that they have stored of them and therefore not be able to recognize that face. Although the most common way for an individual to acquire prosopagnosia has been from neurological damage there is recent research found that many more people suffer from this without actually having neurological damage. This type of prosopagnosia is called developmental or congenial. Someone with this type of prosopagnosia fails to develop standard face processing abilities in spite of normal intellectual and perceptual functions. These individuals with prosopagnosia have suffered this for most of their lives, possibly since birth.

The cause of prosopagnosia without neurological damage “developmental” may have a genetic link. Recent evidence shows that there may be a genetic contribution to developmental prosopagnosia and several case studies report at least one first degree relative who suffers from this (Behrmann & Avidan 2005). Children with autistic spectrum disorders also suffer from face recognition impairments. This may be due to the fact that children with this disorder have impaired social development, and so prosopagnosia contributes to the difficulty of recognizing people.

Individuals with prosopagnosia have developed ways of compensating for their problem by learning to identify people by their clothes, hairstyles, and voice.



Behavior of People with Hereditary Prosopagnosia (How prosopagnosics recognize people by looking at their face)

Prosopagnosia is the inability to recognize someone by looking at their face alone without deficits to sensory or intellectual thinking. Many people with prosopagnosia have been studied in the past to examine how these people behave and react to the people and world around them. However, many of these participants are people who have suffered brain damage and have therefore acquired the inability to recognize someone by their face. People who have been born with prosopagnosia, in other words have hereditary prosopagnosia, are not commonly studied. This is because many of these people usually just think that they have low-functioning face recognition skills or are sometimes not even aware that they have a deficit at all (Schwarzer et al., 2006). Studying people with hereditary prosopagnosia can eliminate extraneous variables such as damage to the brain and accompanying deficits that may affect senses rather than just studying the ability to recognize someone by their face.

In a study by Schwarzer et al. in 2006, of 38 hereditary prosopagnosics, they found that these people can still distinguish normal attractiveness, emotions, and even identify gender. Therefore, they found that the prosopagnosia might rather be an associative deficit. Although there are lots of studies about prosopagnosia, it is still not known whether face recognition and neuronal processes are the only problems or if processes in visual perception and acquiring facial information are also an issue.

In the study by Schwarzer et al., the researchers studied hereditary prosopagnosics by measuring reaction time and movement of the eye during an exercise which asked participants to indicate when they recognize if a face presented is famous or not (Famous Face Task). Another exercise asked participants to distinguish which face presented (of two) was famous and the researchers measured time and movement of the eyes as well (Unfamiliar Face Task). The faces presented to the participants were popular German politicians, television stars and singers and scientists. The researchers also measured the accuracy of people with hereditary prosopagnosia and a control group and found that the experimental group had lower accuracy (60%) when compared to the control group which had 87% correct answers. In the famous face task, the researchers found that the reaction time was longer in hereditary procopagnosic participants than control group participants. The results of the unfamiliar face task showed that both the hereditary and control groups both missed only a single face. These results show that people with prosopagnosia spend quite a bit of time “reading” someone’s face while someone without prosopagnosia can quickly recognize someone by their face. (Schwarzer et al., 2006)

In the same study, the researchers measured the movement of the participants’ gaze when recognizing a famous face. The results showed that participants with hereditary prosopagnosia had a wider range of fixation when compared to the fixation showed by the control group. The hereditary prosopagnosic participants did not look primarily at one spot on the face but rather scanned the entire face looking for certain markers that would indicate a famous person. (Schwarzer et al., 2006)

Behavior of people with acquired prosopagnosia (how prosopagnosics read trustworthiness in faces)

In order to function properly in a social environment, it is essential to have the ability to know the identity of people over time, know how their expressions help understand the meaning of a situation, and know how to make decisions about strangers in a quick and efficient manner. In a study by Todorov and Duchaine, people suffering from prosopagnosia were able to adequately distinguish a trustworthy face from an untrustworthy face. Their study suggests that there are different mechanisms involved in making judgments about a face and mechanisms involved in identifying a face. In the study, patients with damage to their amygdale showed that they could not distinguish a trustworthy face from an untrustworthy face. The participants with prosopagnosia were able to judge a trustworthy face from an untrustworthy face just as well as the control group. In order to combat the possibility that the prosopagnosic participants using expression, gaze, or non-face information to make the judgments, the researchers used three sets of faces that started with a broad view of a face to a more standard image of just a face (refer to Figure 1 below). Their results ultimately suggested that people with prosopagnosia can make normal judgments on trustworthiness and possibly normal judgments on other people’s impressions just as effectively without being able to identify a person’s face (Todorov and Duchaine, 2008).




Treatment

Individuals with prosopagnosia have developed ways of compensating for their problem by learning to identify people by their clothes, hairstyles, and voice.



References
Schwarzer, G., Huber, S., Grüter, M., Grüter, T., Groß, C., Hipfel, M., & Kennerknecht,

I. (2007). Gaze behaviour in hereditary prosopagnosia. Psychological Research.

71, 583-590. doi: 10.1007/s00426-006-0068-0

Todorov, A. and Duchaine, B. (2008). Reading trustworthiness in faces without



recognizing faces. Cognitive Neuropsychology, 25(3), 395-410.

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