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Mintao Zhao, William Warren; Does Path Integration Serve as a "Reference System" for Detecting Landmark Instability?. Journal of Vision 2012;12(9):198. doi: https://doi.org/10.1167/12.9.198.
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© ARVO (1962-2015); The Authors (2016-present)
Humans and other animals use stable visual landmarks to correct or reset their imprecise path integration system during navigation. But this presents a paradox: how does a navigator determine whether landmarks are spatially stable? We tested two hypotheses in the present study: (1) The reference system hypothesis (Cheng, et al., 2007) proposes that path integration serves as a reference system to detect instability in landmark position. (2) The cue consistency hypothesis (Jacobs, 2002) proposes that landmarks that are inconsistent with ≥2 other spatial cues are detected as unstable. Participants performed a triangle completion task while walking in an ambulatory virtual environment. Local landmarks (towers meters away from home) and/or global landmarks (distant mountains) were covertly shifted prior to the home-bound leg. Landmark instability was manipulated by randomly sampling shift angles from a Gaussian distribution with an SD of 1, 2, or 3 times the SD of path integration; a landmark shift greater than JND (= 2.5 SDPI) should be detectable. Participants completely followed landmarks (both local and global) in the low and medium instability conditions, well beyond the JND, but did so only partially in the high instability condition. When local landmarks were consistent with path integration, participants ignored the shifted global landmarks; however, when global landmarks were consistent with path integration, the shifted local landmarks still influenced the homebound path. These results suggest that (1) path integration serves as a very low-precision reference system that only detects highly unstable landmarks; and (2) consistency of landmarks with path integration helps detect instability, but local landmarks have a greater influence on navigation than global landmarks.
Meeting abstract presented at VSS 2012
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