Physical Causes of Face Blindness
An Overview of the Vision System
Most people believe the vision system exists solely in the eyes. In reality, the eyes make up only a small part of the system. Think of the eyes like a camera in a TV studio, because, just like that camera, all the eyes do is pick up the image. For you to get it in your living room, it must be processed through control rooms, a transmitter, an antenna on their tower, possibly through a satellite or cable system, or your own antenna, and finally by your TV set.
Before computers came along to make a lot of the processing decisions, it took a small army to run a TV station. And home TV sets had to be constantly adjusted. Computers and processing circuits in home sets in recent years have kept you in your seat a lot more, and similarly a station can now be run with less engineers because computers are doing a lot of processing at the station's end. So now it takes less guys and a small army of computers. Either way, there's little camera and lots of brain power in the process. And the human vision system is no different.
Nature learned long ago that it is "cheaper" in a sensory system to buy cheap pick up devices and make up for that in the processing. So, just as the camera is a small item in a large TV station, so does the eye play a small part in vision. Like the camera, all the eye does is deliver a bunch of colored dots. It is in the brain that the real work of "seeing" begins.
On the left side of your screen, you just saw a guy standing in a forest. He was wearing blue jeans, blue and white shoes, and a gray coat. He had long hair and a beard. He had his hand resting on a wooden rail. By the style of the railing and pathway, he was probably in a park somewhere.
Your eyes weren't aware of any of that of course. It is your brain that has learned patterns for thousands of different objects such as jeans, shoes, coats, railings, and other people. Though you saw only a head and parts of two hands, you "knew" a whole man was there.
Had you seen me from a different angle, or from the back, you would have also recognized most of these things. So your brain has a way of seeing rotated things as the "same object", though the dot pattern might be quite different.
Had this been a motion picture and I been moving, you would have sensed motion, and where I was headed. Those calculations, too, would have been made by the brain, which in that case would have received nothing but a swirling pattern of changing dots.
You even saw things that your eyes didn't. You can't see the forest, or for that matter much of any of the trees. Yet, the dark green background of vegetation along with the dappled sunlight on the forest floor tell you it's a forest. Sunlight? How do you know it's sunlight? Because the brain knows! By the style of the railing and the pathway, you sensed it was a park. How did you do that? Because the brain knows! After all, all the eye sees is dots:
Look at this image from as close to your monitor as you can. All it is, is dots! And it is exactly what you saw in the first picture, just bigger. Now that you see what your eyes were really seeing, you must be wondering, "Nothing there looks like an eye, or a nose, and certainly nothing looks like hair! How did I see those things?"
Scroll back up to the top of the page briefly, to look at my hair in the original photo, and then come back here. While looking at the original photo, although you don't see individual strands of hair, you feel like there are lots and lots of them. When you look at the enlarged photo, you realize the eyes saw not a strand. Your brain did!
The point being made, of course, is that the brain conducts a huge amount of processing on images the eyes send it. It takes dot patterns and recognizes them as familiar objects, so your mind can manipulate those. It recognizes rotated objects, so you can recognize objects from different directions. It recognizes changes in dot patterns as movement, unless the dot patterns changed because you shifted your glance, in which case it does not!
Thus, most of your sense of vision is not in your eyes at all. It is in your brain. Yet, fabulous as the brain is, the usual circuits in it are not up to one very critical task - that of recognizing people, "telling them apart". People simply look too much alike. Yet, this is a critical need in a highly social species such as we are. Something had to be done.
The solution was to see to it that each of us comes with a highly specialized area in the brain that:
To make sure that this highly specialized area is not overloaded with non-face data, nor is failed to be provided with images that are faces, each of us also comes with a "traffic cop". It is this cop's job to route incoming visual data to the face processor if it is a face, and to the usual circuits if it is not.
- Recognizes people by storing an image of the face of each.
- Makes those unique images available as the "key field" in a filing system each of us builds with data on each person we know. Much like a taxpayer I.D. number with the government, these images are our key to finding (remembering) data stored on each individual.
Where in the Brain Faces Are Recognized
Researchers several years ago isolated facial recognition to a part of the brain known as the "right temporal lobe," and recently they have pinpointed it to a more precise area known as the "fusiform face area." The precise point is not relevant to someone who can't recognize faces, but what is, is this: Researchers have isolated recognition of most patterns other than faces to a different part of the brain on the left side. Since an injury or malfunction can occur in one spot and not the other, this situation establishes a physical explanation for the occurrence of face blindness.
It turns out that the traffic cop described above does not know whether his individual is face blind. Regardless, he will dutifully direct incoming face data onto a different road. For the face blind, that road goes off a cliff. Images sent down that road may be seen, but not really evaluated.
A person could be rendered quite face blind if it were the traffic cop who was defective. In that case, faces would be treated as other data is, and they would get evaluated. But they would get no better treatment than other body parts, such as hands.
An Interesting Quirk - Faces Must Be Right Side Up
Researchers have found that the circuitry that recognizes faces - the circuitry that face blind folks like I lack - only works on faces that are right side up. If faces are shown to non face blind people upside down, they do much poorer with them. On the other hand, researchers have found that the ability of face blind people to recognize faces improves on upside down faces! Apparently the "traffic cop" does not route face data to the special area if it is upside down, but instead to the regular pattern evaluation circuitry. That circuitry is poorer than the face circuitry in most people, but in us it is better than our very poor face circuitry. Of course, the ability to recognize upside down faces is near to worthless. Upside down faces are rarely encountered unless you are being shown them in some researcher's office, or unless you are a monkey swinging in the trees.
Recently I saw a performer take advantage of this quirk. A hundred of us watched an escape artist writhe out of chains while standing on a stage at an Elizabethan fair. At one point he turned his face sideways to slip out of the chains, and he exclaimed, "I need to turn my head sideways. You all don't!" The crowd immediately broke out into laughter because everyone had their heads turned sideways so they could keep the performer's face right side up in their vision!
I suspect I was the only one there, the performer included, who knew why people were responding in this way. The performer had probably discovered this quirk by accident.
By the way, the special face recognition circuitry that most humans have has also been found to exist in monkeys. Researchers have found, though, that in monkeys, the circuitry works on faces even if they are upside down! Must be because monkeys swing in trees.
How You Become Face Blind
There are two ways you can get it. You can either inherit it, as I did, or you can acquire it due to a blow or disease that injures the part of the brain that recognizes faces.
There are two differences noted in the literature between the two groups:
- People who inherit face blindness often are unaware they have it, because they know nothing else to compare their perception to. People who suddenly acquire it lose the ability to recognize people they could pick out before, or they might lose the ability to recognize new people depending on their injury. Either way, the change is very obvious and hard to ignore. (I didn't realize I had face blindness until I was 49 years old. When I was about six years old, though, I remember telling the neighbor kid at the movies that for the bank robbers to only cover their faces was really dumb, because you could still see all the rest of them! So it only took me six years to discover that faces weren't anything special. What took another 43 years was to discover that faces were special to everybody else!)
- People who suddenly acquire face blindness often can't recognize any faces at all. People who inherit it generally can recognize people who they've seen many times. This could be because people who get face blindness from an injury lose all use of a part which partially functions in those who inherit face blindness. Another possibility would be that it is because those who inherit face blindness use alternate methods developed over many years of practice, or constructed at a young age when the mind is still developing and is more malleable and more accepting of using other circuits instead. Which possibility is actually the case has not been pursued in the literature.
A Comment on Two Words - "Recognize" and "Remember"
You'll see those two words used in this book a lot. Of course, one "recognizes" something they "remember" from having seen it before. In talking about face blindness, the two words come up frequently. Rather than scour every thought to make sure I used the "correct" word to fit any given situation - which would be futile anyway - I will discuss exactly what happens. When you see either of those words, you will then know what is going on.
What happens with us is we have great difficulty in remembering faces in the first place. If we have remembered a face in the past, generally because we've seen it lots of times, we will usually then have no trouble recognizing it, should it appear again later. If we fail to recognize a face, it is because we haven't yet seen it enough to remember it.
Once we do remember a face, we are not any more prone to forget it than are most people. I have seen people after a ten year absence and recognized them, but of course there was a time in the past that I saw them frequently. There is one exception to this statement that we aren't prone to forgetting faces, though. It is that people who become face blind due to disease or injury may in fact forget faces they had remembered before the event.
Some of us feel that we really never do remember a face, and that our ability to recognize people we've seen many times comes from the eventual ability to remember other things about them.
Does face blindness run with any other conditions?
I have met or read of quite a few people with Asperger's syndrome, a less severe form of autism, who are face blind. This is not to say that all face blind people have either of those conditions, of course. Face blindness and those conditions are all neurological in nature, though, and when people have one neurological condition, they often tend to also have others. My hearing distortion, for example, is neurological.
There is some research to the effect that face blindness often occurs along with "topographic agnosia," which is an inability to visualize geographical space. I know of one man with that condition who needs precise instructions to go from point "A" to point "B". If he is to return, he needs another set of instructions to get back. If he runs into a detour, he is in big trouble.
Recent (1999) research has found there is a "place processor" in the brain very close to the "face processor". Subjects were shown photographs of buildings, including one made of Lego blocks, and functional MRIs revealed this special place processor was used to evaluate them. A nearby face processor acted on face images. Everything else, including a pistol made of Lego blocks, was processed in the area where general images are dealt with. This research established that there is a parallel "place blindness" to face blindness, and explains why topographic agnosia exists. The requirement that these images be sorted also points out a second function for the "traffic cop" discussed above. The proximity of the face and place areas and the situation that they both deal with special images probably account for why the two conditions often run together.
Not all face blind people are "place blind" however, and I am one who is not. Direction finding and map reading are two of my strongest suits. I have a huge map collection and love to travel, and I never worry about getting lost. I once dreamed of walking across the continent someday, hardly the aspirations of a topographic agnosic.
Despite all this research, of the face blind people I know, more have my hearing impairment (central auditory processing disorder) than have topographic agnosia. This connection has not been investigated by researchers, perhaps because one is a visual deficit and one is auditory.
If you believe you might have Asperger's syndrome, topographic agnosia, or central auditory processing disorder, further information is available on the web.
In the spring of 2004 a substantial number of face blind people on a face blind mail list discovered they all had lower-than-normal body temperatures. Hormones that control body temperature, as well as urination levels and some other physical conditions of the body, are released by glands in the brain. These glands may in some people be affected along with the face processing areas, just as is the case with brain areas processing hearing.
Does Face Blindness Occur More Among Some Peoples?
It is beginning to appear that face blindness is especially common among northern Europeans, and the further north one goes, the higher its incidence. In our support group, we have many more Scandinavians per capita than anything else, while Asians and Africans border on non-existent.
Does Face Blindness Affect Either Sex More Than the Other?
Many neurological conditions are much more prevalent in males than in females. Seeing ratios of 3:1 to 7:1 cited is not uncommon for many such conditions.
We have not noticed any appreciable imbalance between the sexes in our face blind support group, which leads us to suspect that face blindness is either not sex-linked at all, or if it is, the link is a weak one. Until researchers uncover a larger sample of face blind people to study, the actual ratio between the sexes will remain unknown.
How Common Is Face Blindness?
Until recently, it was thought to be extremely rare. As late as the mid-1990s, medical literature reported less than two hundred cases, and only three of those were people born with it - so few some researchers expressed an opinion that one could not be born with it.
When we established our Internet support group, we found about ninety percent of us were born with it. We realized researchers were only seeing the tip of an iceberg - those who acquired it - because those people had suddenly lost something so they noticed, and because they were likely in a doctor's office already, undergoing treatment for the underlying cause. Because of our discovery, researchers are now taking a much stronger interest in those of us born with it.
On January 1, 2002, these two paragraphs were put into this chapter, and they indicate our thought during the first half of this decade:I have actually met seven people who are face blind and did not know that there were others, that I had it, or that I had written about it. Merely my being "out" about it and bringing the subject up at some point were all it took to learn of these people's conditions. Admittedly, the crowd I run with tends to be heavily populated with gay longhairs (as you read more about face blindness you'll learn why there may be more of us in that group), but two of them were not gay longhairs. I have not met thousands upon thousands of people in my life so these numbers tell me face blindness is not as rare as the earliest researchers' numbers might suggest.
Because many don't know of their face blindness, we will never know precisely how prevalent it is until general populations are given a universal test.
Well, in the spring of 2006, two tests made upon random samples from general populations were finally given, and they revealed a very suprising number: About two percent of the population is face blind! A lot of people have the condition and don't realize it, probably because it just doesn't occur to them there could be such a thing.
This section has just discussed how thought on the one question, "How Common Is Face Blindness?", has varied widely over just the decade of 1996 to 2006. It explains why in relatively recent material you may find a large variation in the answers given.
Can One Be Partially Face Blind?
We now have reasonably reliable testing for face blindness, and that testing has shown that some people do have deeper deficits than do others, when it comes to face recognition. On the other hand, be aware that all face blind people recognize some people. We all recognize some people with unusual characteristics, people who we see lots of, or people who are seen where they are expected to be. This is what causes so many of us to fool ourselves for many years into thinking we don't have the condition. If we failed to recognize anyone, a deficit would have from early childhood been blatantly obvious.
Most people who write me thinking they might have a mild case go on to describe events in their lives that indicate they probably have a typical full-blown case. Their "recognizing some people" has led them to this conclusion. They may indeed have a mild case, but most who are impacted enough to be motivated to write, usually don't have a mild case.
This is not something to be upset about one way or the other. The coping skills for whenever you aren't recognizing people are the same. And Appendix B contains information on getting tested in case you really do want to know how your skills compare with the skills of others.
Are There Other Sources of Information on Face Blindness?
This book was written because those of us who have the condition have found information lacking. I drew the information you see on these pages together from these three sources:
- Medical literature. You will find no other books devoted entirely to face blindness (though occasionally a chapter or a page or two might touch on it, in a book that mainly deals with something else). What you will find are a few dozen articles in medical "journals," which are really magazines. Almost all of the articles deal with three subjects:
Of course this type of information is mostly useless to someone whose main interest is how it is to live with the condition. If you look into this literature, you will discover none of the articles deals with the observation of more than a few face blind people, and quite a few deal with the observation of only one person. You will not find anywhere a study involving, say, hundreds of people, a sample size that statisticians seek out if it is available. The condition is just too rare. If you want to do research, you will find useful information in Appendix A - "How To Find Medical Articles on Face Blindness".
- How people do on tests, mostly looking at still photographs, that have been contrived to detect the condition.
- What part of the brain, when it malfunctions, is responsible for the condition.
- How some face blind people recognize faces on a subconscious level (but they still can't use the information any more than the face blind people who don't have this ability can, because it never rises to their consciousness).
- Others who have the condition. I have met over two dozen other face blind individuals in person, and I have corresponded at length with many dozens on the Net. This is where much of the "what it's like to live with it" information comes from. Granted, the size of this sample is not large, but it is the best one can do. Note that the medical researchers mentioned above have been making do with similarly sized samples. The people I have corresponded with are located in the United States, in Canada, and in a few European countries.
- Personal observation. Input in this vein includes not only my life experiences, but also the opportunity to apply them in interpreting the significance of the various things observed in the literature and from others, as recounted above.
ConclusionWe have discussed how a large part of one's "vision" actually occurs in the brain, and how a malfunction in the part that recognizes faces can occur. We have mentioned that recognizing others is important for social beings such as we are, and we next look into how important recognizing other people really is.
"Face Blind!" - Table of Contents
Chapter 1 Introduction Chapter 2 Discovering Face Blindness - BACK Chapter 3 Physical Causes of Face Blindness - YOU ARE HERE Chapter 4 The Importance of Recognizing Others - NEXT Chapter 5 How Most People Recognize Others Chapter 6 Ways To Recognize Others Without Using the Face Chapter 7 How Non-Face Recognition Methods Work in Practice Chapter 8A ...Bill: How I Tell People Apart Chapter 8B ...Pertti: Recognition System - The Essence Model Chapter 9 Effect of Face Blindness on Emotions Chapter 10 Effect of Face Blindness on Sexuality Chapter 11 Effect of Face Blindness on Your Social Groups Chapter 12 Understanding Why People Choose To Look Alike Chapter 13 Ways To Improve Our Lives
Appendix A How To Find Medical Articles on Face Blindness Appendix B Getting Diagnosed (Tested) for Face Blindness Appendix C Links to Other Face Blind People Appendix D Author's Information Page
This document is copyrighted. For information, or to contact the author, go to Appendix D, the Author's Information Page.
Text of this chapter last revised April 29, 2008.