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Information Technologies for Visually Impaired People
Figure 1: Parable of the blind leading the blind. 1568: P Bruegel the Elder, Pinacoteca di Capodimonte, Naples,
Tempera on canvas 86 x 154 cm.
by level changes (stairs, holes in the ground) are only detectable
if they are specifically explored. This "device" dates
back a fair way as we can see in Bruegel the Elder’s dynamic
and almost cinematographic painting "Parable of the
blind leading the blind" (see Figure 1) in which we see a
number of blind people guiding one another, with the leading
ones falling over and bringing the ones behind down
with them.
After the catastrophe of the First World War the number
of blind people grew considerably and the white cane came
to be an instrument with a dual function: firstly it was to
help blind people get around more easily and secondly to
let the people around them know that the person using the
white cane was visually impaired. This invention has been
attributed to George A. Bonham of the Peoria Lions Club,
Illinois, USA in 1930 and its use rapidly became widespread.
The proper use of the white cane, and in particular of
the long cane, requires special training by mobility instructors
to optimize its usefulness.
The Guide Dog
The use of animals as mobility aids is relatively recent.
By way of an anecdote, reproduced below is a photograph,
probably from the late 19th century, showing a blind man
being led by two hens (see Figure 2); the information conveyed
by the photo is minimal and we can only assume that
the level of training that a pair of hens can attain is also
minimal to say the least.
The first attempts to train guide dogs apparently occurred
in Austria in the late 18th century according to references
by Leopold Chimani who in 1827 mentions the case of
Joseph Resinguer who had trained dogs for his own use.
Later the rigid harness (Johann Wilhelm Klein, 1819) appeared
but its use was ignored for practically a century
.
We had to wait for the consequences of the Second World
War before the appearance of dog training establishments
in a number of countries, often as a consequence of individual
initiatives (Gerhard Stalling in Germany, Paul
Corteville in France and later in Spain).
We should also mention here the efforts of the Lions
Club which has encouraged the development of this mobility
and safety aid in many countries for people with visual
impairment, including of course the ONCE.
Electronic Mobility Aid Devices
Late in the 20th century electronic mobility aids began
to appear based on interferometer systems [1]. The first technologies
used were based on the emission and reception of
infrared rays which allowed obstacles to be detected by reflection
up to a distance of 3 to 4 metres (Tom Pouce, Teletact)[2]
(see Figure 3).
Later laser technology devices were used allowing a
greater range and better processing of the information. These
devices may take the form of canes or glasses which interface
with the user in one of two ways; by touch or by sound.
A tactile module enables the user to obtain information about
obstacles. Acoustic systems provide information by means
of tonal differences (higher or lower frequency) depending
on the location of the obstacle and varying loudness to in-
UPGRADE Vol. VIII, No. 2, April 2007 5