No abstract

In a triangle completion task designed to assess path integration skill, younger and older adults performed similarly after being led, while blindfolded, along the route segments on foot, which provided both kinesthetic and vestibular information about the outbound path. In contrast, older adults' performance was impaired, relative to that of younger adults, after they were conveyed, while blindfolded, along the route segments in a wheelchair, which limited them principally to vestibular information. Correlational evidence suggested that cognitive resources were significant factors in accounting for age-related decline in path integration performance.

A series of experiments was conducted to examine the eect of several principle-based practices hypothesized as being important in communicating route knowledge. Results indicated that remembering and following route directions were facilitated by the practice of (a) presenting the directions in correct temporal±spatial order, consistent with the principle of natural order, (b) concentrating information in statements concerned with choice points, consistent with the principle of referential determinacy, and, to some extent, (c) using spatial designations with which most listeners are facile, consistent with the principle of mutual knowledge. In all studies, women had more diculty than men in following the route from verbal directions. Possible avenues for explaining this sex-related dierence are suggested.

Two studies were conducted to evaluate the proposition that macrospatial experience is partitioned, or "subdivided," and that the resulting subdivisions influence judgments of geographic proximity. In Experiment 1, second graders, fifth graders, and college students divided a pictorialized route into subdivisions; in Experiment 2, other subjects from these same grade levels made proximity judgments in a series of two-choice problems. Results indicated that (a) subdivision boundaries were consistent across grade levels with the route used; (b) the younger children tended to base their proximity judgments on their subdivisional organization of the route; and (c) the older children and adults tended to rely on subdivisional information when it was available but to depend on distance estimation and comparison when subdivisional information was absent. These findings are discussed in terms of the developmental and functional implications of redundant means for conceiving of distance relations.

Two experiments investigated how angular estimates reflect bias as a function of response mode, geometric plane of variation, number of implicit categories, memory load and intervening task conditions. In Experiment 1, participants made motor and verbal estimates of incline and azimuth from memory. Estimates in both response modes showed signs of bias predicted by a single-category adaptation of Huttenlocher et al. [Huttenlocher, J., Hedges, L. V., & Duncan, S. (1991). Categories and particulars: Prototype effects in estimating spatial location. Psychological Review, 98, 352-376] category-adjustment model. In Experiment 2, participants made motor estimates of azimuth from memory under a variety of conditions. Stimuli in this experiment were distributed along two contiguous spatial categories. Although increasing levels of cognitive load did not produce a graded effect, participantsÕ estimates were biased and were well described by a multiple-category adaptation of the category-adjustment model. Results from both studies supported an implicit region-based model of bias in spatial memory. These findings were discussed with respect to accounts of spatial memory that propose multiple systems or formats for coding.