Blindfolded adults' use of geometric cues in haptic-based relocation.

Non-visual information is important for navigation in limited visibility conditions. We designed a haptic-based relocation task to examine blindfolded adults' use of geometric cues. Forty-eight participants learned to locate a corner in a parallelogram frame. They were then tested in different transformed frames: (a) a reverse-parallelogram, in which locations predicted by original length information and angle information conflicted, (b) a rectangle, which retained only length information, and (c) a rhombus, which retained only angle information. Results show that access to the environment's geometry through haptic modality is sufficient for relocation. However, adults' performances in the current task were different from that in visual tasks in previous findings. First, compared to previous findings in visual-based tasks, length information lost its priority. Approximately half of the participants relied on angle information in the conflict test and the other half relied on length. Second, though participants encoded both length and angle information in the learning phase, only one cue was relied on after the conflict test. Finally, though participants encoded the target location successfully, they failed to represent the global shape of the environment. We attribute adults' different performances in haptic-based and visual-based tasks to the high cognitive demands in encoding and using haptic spatial cues, especially length information.

Young children's representation of geometric relationships between locations in location coding.

From an early age, children are able to use surface layout geometry and landmarks to search for a hidden toy when disoriented. Theoretical debate remains regarding whether children represent locations based on the global environment or on local cues. Exploring whether children construct and use the relationships between discrete locations of the global environment can provide direct evidence regarding this issue. We investigated young children's representation of two geometric relationships: diagonal relationships (Experiment 1) and same-side relationships (Experiment 2). Children (4- and 5-year-olds) were tested in a square room with a distinctively colored wall. Children completed two tasks. In a two-location task, children watched two toys hidden in two corners that formed one of the two relationships. After disorientating children, the experimenter uncovered one toy and children searched for the other one (target). In a one-location task, only one toy was hidden. In both experiments, children's performance was better in the two-location task than in the one-location task. Furthermore, accuracy in the two-location task of Experiment 1, in which the two corners formed a diagonal relationship, was higher than that of Experiment 2, in which the two corners formed a same-side relationship and a correct location required the combination of this relationship and landmark. These findings suggest that at least by 4 years of age, children can construct geometric relationships between individual corners in their spatial representation and support the global accounts of young children's location coding.