Mental Rotation of a Tactile Layout by Young Visually Impaired Children

Abstract

Mental rotation tasks have been used to probe the mental imagery both of sighted and of visually impaired people. People who have been blind since birth display a response pattern which is qualitatively similar to that of sighted people but tend to respond more slowly or with a higher error rate. It has been suggested that visually impaired people code the stimulus and its (or their own) motion in a different way from sighted people-in particular, congenitally blind people may ignore the external reference framework provided by the stimulus and surrounding objects, and instead use body-centred or movement-based coding systems. What has not been considered before is the relationship between different strategies for tactually exploring the stimulus and the response pattern of congenitally blind participants. Congenitally blind and partially sighted children were tested for their ability to learn and recall a layout of tactile symbols. Children explored layouts of one, three, or five shapes which they then attempted to reproduce. On half the trials there was a short pause between exploring and reproducing the layouts. In an aligned condition children reproduced the array from the same position at which they had explored it; in a rotated condition children were asked to move 90 degrees round the table between exploring and reproducing the layout. Both congenitally blind and partially sighted children were less accurate in the rotated condition than in the aligned condition. Five distinct strategies used by the children in learning the layout were identified. These strategies interacted with both visual status and age. We suggest that the use of strategies, rather than visual status or chronological age, accounts for differences in performances between children.

Differences between Early-Blind, Late-Blind, and Blindfolded-Sighted People in Haptic Spatial-Configuration Learning and Resulting Memory Traces

“…While the sighted used more board referrals than the blind to point out the locations of objects (allocentric, extrinsic; cf Ungar et al 1995), the blind referred more to other objects on the board (allocentric, intrinsic) than the sighted. Although both types of descriptions can be called allocentric, one could argue that the nature of the descriptions is different, and may be indicative of differences in which the spatial information is coded in the blind and the blindfolded-sighted.…”

“…While the first three trials may primarily depend on manual dexterity, the rotated configuration requires an updating of positions and performance is detached from the stored movement memories. Previous studies (Hollins and Kelley 1988;Ungar et al 1995) have shown an advantage for visually experienced individuals under these circumstances.…”

“…Interestingly, delayed pointing by blindfolded-sighted has indeed been suggested to reveal an allocentric coding pattern, in contrast to early-blind who might be more egocentrically oriented (Rossetti et al 1996;Gaunet and Rossetti 2006). Ungar et al (1995) and Hollins and Kelley (1988) offered unlimited time to participants to learn the objects and their locations. They demonstrated an advantage for the visually experienced in the localisation of objects, yet only after object configuration rotation.…”

“…Following Ungar et al (1995), who observed different strategies employed to encode spatial configuration of objects, we examined the number of spatial descriptions in which the object's position (a) was pointed out by referring to the board (``the cross was the top left of the board''); (b) was described with respect to another object (``the triangle was right of the cross); and (c) was described with respect to a part of the participant's body (``the circle was over here'', or``the circle was to my left''). In order to get a measure of the characteristics of the descriptions irrespective of possible differences in object descriptions, incorrect or unclear descriptions were also included.…”

The Effectiveness of Facility Assembly Devices Concerning the Wayfinding of People with Visual Impairments

“…The tactile map, being recognized as an effective source of information about both immediate and distant places in the environment contributes to successful wayfinding (Passini et al, 1986). Although blind people can perceive the spatial layout of the represented area by reading and memorizing a tactile map, they generally read it more slowly and understand it less than do sighted people who see a visual print of the same map (Ungar et al, 1995a), especially, when a tactile map represents a large environment or an environment with complex circulation. Therefore, more effective methods have been taken into account in regard to minimizing the time and effort that it takes for people with visual impairments to learn the unknown environments.…”