Mc. Wanet

Processing of auditory information by the blind in spatial localization tasks

Spatial localization of sonorous targets in the near space, by blindfolded sighted subjects and by early- or late-blind subjects, was investigated using a two-dimensional coordinate system (direction and distance) in various experimental conditions: The head was free or restrained, and the subject’s response was either a finger pointing on a coordinate grid in open loop or a verbal assessment based on a simple reference system. The results for each group of subjects were processed by dealing separately with distance and direction parameters. They show that with early blinds, only the distance evaluation was particularly impaired. Performance did not seem to depend much on whether the head was restrained or free. Finally, direction was best evaluated by motor responses, whereas distance was more accurately judged verbally.

Development of the Air Righting Reflex in Cats Visually Deprived Since Birth

SummaryClassical experiments on the ability of cats to turn in the air during a free fall, the air righting reflex, have shown that vestibular and visual cues can play a role in this behavior. The development of this air righting reflex in kittens blinded since birth has been studied. The results show that the development in the blinded kittens is the same as in normal kittens with vision: mature by 33 days. This result and the comparison with other studies confirm that the air righting reflex is primarily a vestibular controlled reaction.

Design of Sensory Substitution Systems for the Blind

Many efforts have been devoted to the design of sensory aids for blind persons. Since the introduction of Braille last century, a classical way has been to use the remaining sensory systems (mainly the auditory and tactile systems) as substitutive input to the brain. Recent developments in electronics and computer-science have made possible the design of sophisticated sensory and artificial substitution systems. An alternative approach, pioneered by Brindley and Lewin (1968), has been to bypass the impaired visual receptor organ (eye) by electrical stimulation of the visual cortex.

Guided locomotion in cats with and without vision

AbstractSpatial representation of early blind human subjects is usually described as impaired when compared with sighted blindfolded people. Is that also true in other species? We tried to answer this question using cats, visually deprived since birth or early after birth. Is there a good spatial representation in these cats, and could they behave as accurately as normal cats when they are placed in the same experimental conditions?

Improvement in Assessment of Direction and Distance, By Blind Subjects Using An Ultrasonic Prosthesis

AbstractSpatial behaviour is usually described as impaired by blindness (Rieser et al., 1982). The accuracy of the spatial representation seems to depend on the amount of visual experience of the subjects, early blind subjects being less performant for spatial tasks than late blind subjects. To verify this, we compared the performance of blind subjects to the one of a control group (blindfolded sighted subjects), for two spatial tasks. After that, we tested the possible improvements in these tasks for blind subjects using an ultrasonic prosthesis.