TEXT C A blind baby is doubly
handicapped. Not only is it unable to see, but because it cannot receive the
visual stimulus from its environment that a sighted child does, it is likely to
be slow in intellectual development. Now the ten-month old son of Dr. and Mrs.
Dennis Daughters is the subject of an unusual psychological experiment designed
to prevent a lag in the learning process. With the aid of a sonar-type
electronic that he wears on his head, infant Dennis is learning to identify the
people and objects in the world around him by means of echoes.
Dennis and a twin brother, Daniel, were born last September almost three
months too early. Daniel died after five days, and Dennis developed retrolental
fibroplasias, an eye disorder usually caused by overexposure to oxygen in an
incubator. He went blind, but through a pediatrician at the premature unit
where he was treated, the Daughters were contacted by Dr. Tom Bower, a
psychologist from the University of Edinburgh then serving a fellowship at the
Stanford University Centre for Advanced Study in the Behavioural Sciences. Bower
wanted to see how a blind infant might respond if given an echosounding device
to help him cope with his surroundings and the Daughters agreed to
help. By the time the child was six weeks old, his parents
noticed that he continuously uttered sharp clicking sounds with his tongue.
Bower explained that blind people often use echoes to orient themselves, and
that the clicking sounds were the boy’s way of creating echoes. This, Bower
believed, made the child an ideal subject for testing with an electronic
echosounding device. Signals: The device used in the study is a
refinement of the "Sonicguide", an instrument produced by Telesensory System,
Inc., of Palo Alto, Calif. , and used by blind adults in addition to sane
or guide dog. As adapted for Dennis, it consists of a battery-powered
system about the size of a half dollar that is on a headgear. A transmitter
emits an ultrasonic pulse that creates an 80-degree cone of sound at 6 feet.
Echoes from objects within the cone are perceived as sounds that vary in pitch
and volume with the size and distance of the object. The closer
an object is, he lower the pitch, and the larger the object, the louder the
signal. Hard surfaces produce a sharp ping, while soft ones send back signals
with a slightly fuzzy quality. An object slightly to the right of Denny’s sends
back a louder sound to his right ear than to the left. Thus, by simply moving
his head right and left and up and down, he can not only locate an object but
also get some notion of its shape and size, thanks to the varying qualities of
sounds reaching his ears as the cone of ultrasound passes its edges. Dennis
likes to use the device to play a kind of peek-a-boo with his mother. Standing
on her knee and facing her directly, he receives a strong signal in both ears.
By mining his head away, he makes her seem to disappear. "From the first time he
wore it," says Mrs. Daughters, "it was like a light going on in his
head." The boy also learned to identify many objects, including
his favourite toy, a robber caterpillar with six antenna-like projections coming
out of its body. And at six-and-a-half months, when a teething biscuit was held
in front of Dennis, the child immediately grabbed it with both hands and put it
into his mouth. So far, the study has shown that a normal blind
baby can employ echoes as well as, or even better than, an unsighted adult can.
What remains to be determined is how well the device will help Dennis cope with
his surroundings as he begins to walk and venture further into his environment.
Meanwhile, Telesensory, Inc. , is working on the development of a sonar device
with somewhat the same sensitivity as Dennis’s for use by school-age
children. How could Dennis distinguish between a book and a pillow of the same size and at an equal distance in front of him A book would produce ______.