Frontiers in Tactile Perception

Frontiers in Tactile Perception

A Call for Research on Braille Reading and Haptic Perception

by T. V. Cranmer

From the Editor: Tim Cranmer is President of the International

Braille Research Center and Director of Research for the National Federation

of the Blind.

It is surprising how little we know about how blind people write and read

Braille. It is all the more surprising once it is understood that writing is just as

important to the blind as it is to all people who possess normal sight. It fulfills the

same function for me as it does for you in the audience with your pens and pencils near to

hand.

There is something about the written word that delights the human mind.

There is something mystical, miraculous, and not fully understood that happens when the

trained and practiced fingers of a blind reader skim the symmetrical patterns of Braille

dots that transfer to his conscious mind words, thoughts, ideas, and emotions from a

friend or from people long dead.

Braille seems magical to those who have forgotten that infants

instinctively reach out to touch things they see to grasp their new surroundings better.

Braille is mystical to those who forget that children want to hold a toy in their hands

and won't settle for just looking at it. We all must be reminded from time to time that

touch and sight are peers in the hierarchy of the senses.

We who are blind haven't always enjoyed the marvel of the written word.

According to a usually reliable source, National Geographic, our progenitor, Lucy,

the hominid that made bipedal footprints on the shore of a lake in Africa, lived some

three million years ago. I think it is safe to assume that Lucy was illiterate. According

to the venerable Encyclopaedia Britannica, writing appeared in Mesopotamia some

eight thousand years ago. Braille appeared in France about 1829. From these facts it is

clear that the time writing first appeared to the time Louis Braille invented the code

that the blind use today spanned several thousand years. In this long interim it was left

to others, sighted others, to record the blindness experience.

Writing, in all its forms, is a marvelous invention of man. The encoded

presence of your name or mine in print or Braille continues to delight us. A case in

point:

The interview that I gave for an appearance on the "Sixty

Minutes" TV program lasted for some four hours. When the show aired, my part lasted

but a moment. A big part of that brief appearance on camera was focused on Lesley Stahl's

name written in Braille on a Braille Lite. My hands were shown reading as I spoke "L

E S L E Y, S T A H L." No mention was made of the fact that I had to ask the hostess

how to spell her name because I had never before seen it written. The orderly pattern of

Braille dots that represented the name of Lesley Stahl was magical. It possessed

entertainment value as well as some potential educational merit. In the view of the show's

producers, it was worthy of the attention of a national television audience.

Braille is the written language of the blind. It would be difficult to

overemphasize the importance of Braille. It is a regrettable fact, often repeated

nowadays, that 70 percent of all blind people are unemployed or under-employed. It is a

fact, not repeated often enough, that ninety percent of blind people who read Braille are

employed in decent jobs.

Braille is not much understood and little appreciated by the general

public. Far too many educators share the public's indifference to the importance of

Braille to those blind people who master it. After decades of neglect by trained teachers

of the blind, many individuals in the blind community have been led to believe that there

are viable alternatives to learning Braille. There is none. The same educated people who

believe that there are viable substitutes for Braille will scoff at the notion that

substitutes for print are available to the sighted.

Over the years there have been several studies to understand how blind

people read Braille. Psychologists and other professionals who could not read Braille

efficiently, if at all, undertook most of these research efforts. I have been unable to

identify even one study of Braille reading and writing that included subjective insights

from blind individuals who were participating in the investigation. One might expect that

good Braille readers would be asked to explain how they read.

The blind community and society will greatly benefit from new, enlightened

research that leads to better training in reading and writing Braille. We are in need of

better knowledge of the physiology of touch. We need accurate measurement of transmission

bandwidth through the sense of touch, that is, to ask: How many parallel channels can be

simultaneously carrying tactile data to the brain? How many bits per second can flow

through each tactile channel? What are the physiological limitations inherent in tactile

communication?

More information is needed on haptic recognition of objects large and

small and how tactual imagery is acquired and stored from the practical experience of

blind individuals. How dependent is haptic interpretation on context? The list of

opportunities for research could be extended indefinitely.

Please imagine this haptic experience, as I did a long time ago. I was

asleep in the middle seat of an airplane. The aisle seat to my right was empty. That is to

say that it was empty when I went to sleep. Upon waking, I shifted the position of my

right hand from my lap and allowed it to drop onto the seat at my right. It came to rest

on a nude knee. The time that my hand remained at rest on the knee could have been

measured only in milliseconds. That was quite long enough for me to recognize that my hand

should be moved, that there was a passenger in the seat that had previously been empty,

that the passenger was wearing shorts or a miniskirt, that it was probably a young lady or

a young boy. If I could but have returned my hand for a second peek, I could have

determined the gender and age of the knee and a measure of unhappiness experienced by the

knee's owner.

The wealth of information that passed through my hand in the instant of

contact defies analysis. With all my insight I can offer only the lame observation that

context played a major role in every aspect of the event.

Better understanding of haptic perception should be pursued through new

research inspired by new insights into how real blind people interact with the physical

world. Let's begin with Braille reading.

I posit that the cognitive processes involved in reading print and Braille

are essentially the same. The image flowing through the specialized regions of the brain

where they are stored and processed for their linguistic meaning are the same for all

reading, whether done visually or through the sense of touch. Recent articles in

scientific journals, as well as the popular press, report that the visual cortex in the

brain of sighted and blind individuals is the site where imagery is stored. Thus the only

difference between reading print and reading Braille is in the perceptual modality

necessary to establish a train of imagery passing through the visual cortex--that is, the

visual path to the brain on the one hand and the tactual path to the brain on the other

hand.

I wish to emphasize this process: Print readers must establish a stream of

images in the visual cortex, and Braille readers must likewise establish a flow of images

through the visual cortex. Images passing through the visual cortex of the brain of

sighted and blind readers are true images in both cases even though they are encoded in

visual perceptions and tactual perceptions respectively.

Other researchers will have to repeat experiments that indicate that the

same region of the brain is used for processing tactile and visual images before

professionals in the field will accept it. Once the role of the visual cortex in reading

has been established, the investigator into factors affecting Braille reading will be free

to focus entirely on the mechanical interface through touch with the Braille page. This

understanding will also reduce the importance of the role of comprehension as one measure

of reading speed.

Grasping the meaning intended by the author of a written passage may play

no more than a minor role in the transformation of the written words to their equivalents

in natural speech. Sighted people who read well can do so without comprehending the

information contained therein. This is common knowledge among blind students who have

employed sighted individuals to read aloud from a textbook.

I cannot resist a brief digression to share with you one of my experiences

with sighted readers. Back in my younger days, when I was enthralled with chemistry and

could not find a book in Braille on the subject above the beginner's level, I hired a

young lady to read an advanced book on chemistry. She read it with ease. She read it with

as much speed as I could tolerate. At one point I asked her if she understood what she was

reading. With exaggerated good humor she replied: "Oh, yes. I understand every word.

But it's the sentences and paragraphs that give me problems."

Once we accept the premise that the focus of an inquiry into factors

affecting Braille reading will be confined to those relating to touch alone, it will be

necessary to identify the specific factors to be evaluated. Here is a brief starter list

of factors affecting reading by touch:

* Compliance of the skin covering finger pads. The top layers of skin that

contact Braille must be soft enough to be deformed by the pattern of the Braille

characters as they pass beneath the reading fingers.

* The area of the skin brought in contact with the line of Braille being

read has a critical relation to the efficiency with which the tactile information is

passed to the brain. This is a variable of the reading strategy of each individual: one

finger, two fingers, or more; one hand or two hands. The greater the skin contact with the

Braille line, the larger the tactile view.

* Temperature of the reading fingers. Cold fingers do not make for good

Braille reading.

* Alignment and tracking of hands and fingers with the lines of Braille

being scanned. Misalignment and poor scanning may result in contact with Braille on an

adjacent line. This may corrupt the tactile data flow. Engineers would refer to this extra

tactual stimulation as signal noise. A maximum ratio of signal to noise will contribute to

the reading process.

This partial list of largely mechanical factors affecting Braille reading

omits any reference to reading strategy. Some researchers have attempted to analyze

reading techniques of blind subjects by studying video recordings of their hands as they

read in a laboratory setting. Other researchers have explored Braille reading by

presenting Braille one character at a time using a contrivance called a

tachistotactometer. I suspect that the use of video recordings and tachistotactometers

tells us more about the sighted investigators' love of technology than the technique used

by the reader of Braille.

Now here is my next posit; one sure to offend the establishment: The best

information about effective Braille reading technique will come from analysis of

subjective reports from skilled Braille readers themselves. I contend that no amount of

observation by a sighted investigator can ever surpass the subjective reports of what is

going on at the interface between the blind reader and the Braille page. I also believe

that this assertion applies equally to continuous Braille reading and to searching for

specific information in a Braille book.

As we harvest the fruits of our research into tactile reading and haptic

perception, a clear set of principles for designing computer-controlled, tactile

transducers should emerge. These should be of two types. The first tactile display may

consist of a printer that produces layered deposition of solid material on paper with the

fine detail required for representing objects in three dimensions. A human face would be a

good choice to exemplify tactile image printing. The face could be built up as a bas

relief with true X and Y dimensions and a Z axis scaled to meet minimum requirements to

provoke immediate recognition of such features as nose, mouth, eyes, and so forth. With

sufficient resolution and detail, a bas relief image formed in this way could take on the

aspect of a tactile photograph. I should be excused for coining the term tactograph for

this medium. In fact, I submit that tactographs of human faces could be produced in the

very near future with minor modification of machines used in industry today in rapid

prototyping applications.

It does not require a great leap of confidence to imagine the second

transducer, which should be a computer-controlled, dynamically variable surface topography

capable of producing refreshable bas-relief imagery. Very little in technology today

appears suited to the manufacture of a display of this complexity. New materials must be

found or designed to this end. None will be found or designed till the men and women in

various branches of materials science are inspired to begin the quest with the same zeal

with which they now pursue materials with desirable electro-optical properties.

The International Braille Research Center is eager to support fully or

partner with any individual or group attending this conference who shares our feel for the

future, who can imagine the instruments to augment tactile perception in order for the

blind to feel that which they cannot now touch and find the path we must follow to build

the tactile technologies of the future.