Semantic and visual factors affecting the representation of map information.

In past research evidence has been found for both mental imagery and propositional hierarchies in subjects' map representations. How the visual and semantic factors associated with maps influence the use of one form of representation or another was the subject of the study reported here. Subjects were required to make relational judgments about city pairs. The results of experiment 1 indicated that superordinate relationships (the relationship of the counties of which the cities were members) affected only the most difficult perceptual judgments, but affected all judgments made from memory. Experiment 2 was done to determine the extent to which these findings were attributable to perceptual distortions rather than propositionally stored rules. Results of experiment 3 showed the degree of perceptual distinction necessary for propositional rules to have no significant influence on relational judgments.

Misaligned maps lead to predictable errors.

Three experiments were conducted to investigate the ability of subjects to make judgments of direction when using misaligned maps. Two hypotheses were proposed (i) errors would fall into two lawful categories--mirror-image errors and alignment errors; (ii) the effect of map orientation would generalize to a different mode of responding than has been used in previous studies. Support for both hypotheses was obtained. The results are discussed in terms of the mental processes used to align maps to spaces, and the task demands required by different response modes.

The importance of alignment in blind subjects' use of tactual maps.

An experiment was conducted to test for the presence of alignment effects (previously found in sighted map users) in blind and visually impaired subjects using tactual maps. The term 'alignment effects' refers to the fact that when points represented as further up on a map do not correspond to points forward from the user in the environment, errors in the directional judgments made by subjects are greatly increased. The results show that alignment effects do exist in blind and visually impaired map users. Blind subjects encoded maps using the 'up equals forward' rule, and demonstrated some similarity to sighted subjects in the types of errors made. There was also some indication of improved performance over repeated trials. Differences between blind and sighted subjects were also found and were tentatively attributed to visual experience with object transformations and/or representational variables. Subject background variables were also investigated and some relationships between background of the subject and performance were drawn.