PROCESSING CAPACITY LIMITATIONS IN PICTORIAL AND SPATIAL REPRESENTATIONS IN THE TOTALLY CONGENITALLY BLIND

The study of visuo-spatial imagery abilities in totally congenitally b lind people may be instrumental in understanding the contribution of v isual experience to imagery processes. In the present paper visuo-spat ial imagery capacity was explored through a task devised by Kerr (1987 ) and adapted for presentation to the blind, in which subjects were as ked to imagine either two- or three-dimensional matrices of different complexity and to follow a mental pathway. The first experiment showed that blind people have difficulty with three-dimensional matrices whi ch are within the reach of sighted people, and that their performance is affected by the processing rate. In the second experiment the spati al and pictorial components of visual imagery were analyzed by way of the same spatial task and of a pictorial-tactual task in which subject s had to match a mental representation of a pathway to a tactually exp lored wire silhouette. On the latter task, blind people did not meet a ny particular difficulty, probably because they could form representat ions using other sensory modalities and because they were skillful in tactual exploration. These data suggest that research on the blind can not easily contribute to the distinction between the spatial and picto rial components of visual imagery.