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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.

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In this paper we summarize five experiments that were designed to investigate how tactile maps contribute to the cognitive maps of people with visual impairments. In two experiments we demonstrated that tactile maps can contribute to peoples' ability to learn a route through an unfamiliar area. From the results of two further studies, we argue that compared to people with sight, people with visual impairments have greater difficulty encoding information from a map. We considered this directly in a fifth experiment by investigating how people with visual impairments search and learn a map. We found that they used less efficient strategies than people with sight. We conclude that tactile maps are an important source of geographical information when people need to learn about new environments, but we also point out that to benefit most from tactile maps people need to encode the map information as effectively as possible. As people with visual impairments do not always use the most appropriate encoding strategies we suggest that tactile map users might benefit from greater experience and training in map encoding strategies.

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