James Negen, Angela Sandri, Sang Ah Lee, Marko Nardini. Boundaries in Spatial Cognition: Looking like a Boundary is More Important than Being a Boundary. June 12, 2019. doi: https://doi.org/10.1101/391037

Abstract

Large walls and other typical boundaries strongly influence neural activity related to navigation and the representations of spatial layouts. They are also major aids to reliable navigation behavior in young children and non-human animals. Is this because they are physical boundaries (barriers to movement), or because they present certain visual features, such as visually extended 3D surfaces? Here, these two factors were dissociated by using immersive virtual reality and real boundaries. Eighty adults recalled target locations in one of four environments: plywood, where a virtual wall coincided with a large piece of real plywood; pass through, where the virtual wall coincided with empty space and participants could pass through it; pass over, where the virtual wall was projected downward to be visible underneath a transparent floor; and cones, where the walls were replaced with traffic cones. One condition had features that were boundaries and looked like boundaries (plywood); two had features that were not boundaries but looked like boundaries (pass over/through); and one had features that were not boundaries and did not look like boundaries (cones). The precision and bias of responses changed only as a function of looking like a boundary. This suggests that variations in spatial coding are more closely linked to the visual properties of environmental layouts than to whether they contain physical boundaries (barriers to movement).

Conclusion

Experiencing that an item is a (physical) boundary, independent of how much it looks like a typical boundary, does not directly affect adult participants’ coding of the locations around it. In contrast, non-boundaries that vary in how they look can lead to substantial differences in the pattern of responses. This is the clearest evidence to date that the typical boundaries in natural scenes have their particular effects on spatial cognition because of visual aspects such as horizontal extent, the presence of a visually extended 3D surface, or large-scale structure – not because they limit navigation. 

James Negen, Angela Sandri, Sang Ah Lee, Marko Nardini. Boundaries in Spatial Cognition: Looking like a Boundary is More Important than Being a Boundary. June 12, 2019. doi: https://doi.org/10.1101/391037