What is prosopagnosia? ↩︎
Prosopagnosia, also called face blindness, is an impairment in the recognition of facial identity. Prosopagnosics often have difficulty recognizing family members, close friends, and even themselves. They tend to use alternative routes to recognition, but these routes are not as effective as recognition via the face. Not surprisingly, prosopagnosia can create serious social problems. Several estimates suggest 1 in 50 people are prosopagnosic. It can be accompanied by recognition impairments affecting other categories such as scenes, cars, and facial expressions of emotion, but in some cases, face recognition deficits occur in isolation.
Symptoms of prosopagnosia ↩︎
Most people occasionally have trouble recognizing faces they have seen before, but prosopagnosia is much more severe than these everyday problems. Prosopagnosics have difficulty knowing whether they have seen a face before, and they often have problems recognizing faces they have encountered many times. In extreme cases, prosopagnosics have trouble recognizing even those people that they spend the most time with such as their spouse and children. It is important to note that prosopagnosia is defined by problems recognizing faces, not recalling names.
One of the telltale signs of prosopagnosia is great reliance on non-facial information such as hair, gait, clothing, voice, and other information. One of the most common complaints of prosopagnosics is that they have trouble following the plot of television shows and movies, because they cannot keep track of the identity of the characters. Prosopagnosics also sometimes have difficulty imagining the faces of people they know.
If you would like to assess your face recognition abilities, our collegues currently have a test of face recognition available. This test includes feedback on how your score compares to the scores of people with normal face recognition.
Reports of prosopagnosia date back to antiquity, but Bodamer's report (1947) of two individuals with face recognition deficits was a landmark paper in that he extensively described their symptoms and declared it to be distinct from general visual agnosia. He referred to the condition as prosopagnosia, which he coined by combining the Greek word for face (prosopon) with the medical term for recognition impairment (agnosia).
Acquired prosopagnosia ↩︎
Prior to the 21st century, almost all cases of prosopagnosia that were documented resulted from brain damage, usually due to head trauma, stroke, or degenerative disease. Cases due to brain damage are called acquired prosopagnosia: these individuals had normal face recognition abilities that were then impaired. Acquired prosopagnosia is often (though not always) apparent to people who suffer from it, because they have experienced normal face recognition in the past and so they notice their deficit. If you have experienced a noticeable decline in your face recognition abilities, you should contact a neurologist; any sudden decline may indicate the existence of a condition that needs immediate attention.
Developmental prosopagnosia in adults and children ↩︎
In cases of developmental prosopagnosia (sometimes called congenital prosopagnosia), face recognition problems are present early in life and are caused by neurodevelopmental impairments that impact face processing mechanisms. Face recognition ability varies substantially in people with normal abilities; some people are really good, others are poor, and most people are somewhere between these extremes. People with developmental prosopagnosia appear to make up the low end of the distribution of face recognition abilities. On the opposite end of the distribution are super recognizers, who have extraordinarily good face recognition. If you think you’re a super recognizer and you’re interested in research participation, please contact us.
Developmental prosopagnosics have never recognized faces normally so their impairment is often not readily apparent to them. As a result, many developmental prosopagnosics are unaware of their prosopagnosia even as adults. Developmental prosopagnosia in children can be especially difficult to identify. For more information on developmental prosopagnosia in kids, please visit this website.
Many people with developmental prosopagnosia report family members with face processing deficits, and several families with multiple developmental prosopagnosics have been documented. A genetic contribution to many cases of developmental prosopagnosia fits with results from twin studies in the normal population that indicate that differences in face recognition ability are primarily due to genetic differences.
The organization of face processing ↩︎
Face processing in the normal brain involves a number of different processes. Studies of the brain using functional MRI and other techniques show that numerous brain areas respond much more strongly to faces than to other visual categories. In the figure below, six face-selective areas are shown on the right hemisphere, and although the right hemisphere is more important for face recognition than the left hemisphere, a fairly similar set of areas is present in the left hemisphere. These areas are interconnected, and all become active when faces are viewed.
Prosopagnosia results from problems in the face network. Acquired prosopagnosia results from damage to the network, whereas developmental prosopagnosia is caused by atypical development of the network. Given that many areas as well as connections between areas contribute to face processing, there are many ways for the network to malfunction and so it is likely that many types of prosopagnosia occur. Understanding these different subtypes of prosopagnosia is one of the major research aims of our laboratory.
Research questions ↩︎
Currently, we have a limited understanding of prosopagnosia, and so there are many research questions that need to be answered. Some of the major questions are:
- What computational procedures are impaired in prosopagnosia?
- What brain regions are impaired in prosopagnosia?
- What genes are involved with genetically-based developmental prosopagnosia?
- Are there methods that prosopagnosics can use to improve their face recognition?
Research participants needed ↩︎
If you believe that you are prosopagnosic or have other types of recognition impairments and are interested in becoming involved with research, please contact us using our form. We will try to get you involved with studies we are conducting or we can try to put you in contact with researchers in your area. We carry out studies over the internet so distance is not an impediment to participating in many of our behavioral studies.
In addition to providing important data for research on prosopagnosia, prosopagnosics often find that they gain greater insight into their condition from testing. For example, we assess abilities with a variety of object categories (horses, flowers, cars, etc.) and test other types of face processing (e.g., emotional expression recognition; sex, age, and attractiveness via the face; gaze perception). These are abilities that are often difficult to self-assess and realization of strengths and weaknesses can often help individuals better cope with visual recognition deficits.