"Taller and Shorter": Human 3-D Spatial Memory Distorts Familiar Multilevel Buildings

Abstract

Animal experiments report contradictory findings on the presence of a behavioural and neuronal anisotropy exhibited in vertical and horizontal capabilities of spatial orientation and navigation. We performed a pointing experiment in humans on the imagined 3-D direction of the location of various invisible goals that were distributed horizontally and vertically in a familiar multilevel hospital building. The 21 participants were employees who had worked for years in this building. The hypothesis was that comparison of the experimentally determined directions and the true directions would reveal systematic inaccuracy or dimensional anisotropy of the localizations. The study provides first evidence that the internal representation of a familiar multilevel building was distorted compared to the dimensions of the true building: vertically 215% taller and horizontally 51% shorter. This was not only demonstrated in the mathematical reconstruction of the mental model based on the analysis of the pointing experiments but also by the participants' drawings of the front view and the ground plan of the building. Thus, in the mental model both planes were altered in different directions: compressed for the horizontal floor plane and stretched for the vertical column plane. This could be related to human anisotropic behavioural performance of horizontal and vertical navigation in such buildings.

Fig 1. Pointing locations.

Pointing locations as seen from above overlaid on an architectural ground plan of the hospital building. Note that the targets were not placed more toward the corners of the building but rather were distributed all over the building.

Fig 2. Pointing directions.

Horizontal (azimuth, black dots) and vertical (elevation, red stars) mean pointing directions (error bar gives circular SD) plotted over mean target direction. Accurate pointing directions would agree with the dashed blue line. Orientation of the participants during the pointing task coincided with the short axis of the main building (tall red building part in Fig 3) and with zero azimuth angle. Note that horizontal pointing angles were on average smaller than target angles, indicating a reduction of perceived length of the building, while the opposite was the case for vertical angles, indicating an overestimation of the building’s height.

Fig 3. 3-D model of the hospital building.

A: original building. B: building reconstructed from the averaged pointing directions of the participants assuming a linear transformation of the building. C: building reconstructed from pointing but allowing for linear and quadratic transformation. Green flag indicates the position of the participants in the building. Red: main building. Note that the mental model appears to be compressed for the horizontal floor plane, stretched for the vertical column plane, and curved toward the subjective straight ahead.

Fig 4. Aspect ratios of the main building.

A: Front view (top row) and top view (bottom row) of the main building. Left column: true proportions of the building. Middle column: Transformed building according to averaged pointing directions. Right column: Transformed building according to averaged aspect ratios from participants’ drawings. Note that depictions are shown at equal height. B: Bar graph of aspect ratios. Left length:height, right: length:width. Left bar (light gray): true aspect ratio of the building, middle bar (gray): averaged ratios of transformed buildings according to individual pointing directions, right bar (dark gray): ratio taken from individual drawings. Error bars denote standard deviation.