Environmental stability modulates the role of path integration in human navigation

Abstract

Path integration has long been thought of as an obligatory process that automatically updates one's position and orientation during navigation. This has led to the hypotheses that path integration serves as a back-up system in case landmark navigation fails, and a reference system that detects discrepant landmarks. Three experiments tested these hypotheses in humans, using a homing task with a catch-trial paradigm. Contrary to the back-up system hypothesis, when stable landmarks unexpectedly disappeared on catch trials, participants were completely disoriented, and only then began to rely on path integration in subsequent trials (Experiment 1).Contrary to the reference system hypothesis, when stable landmarks unexpectedly shifted by 115° on catch trials, participants failed to detect the shift and were completely captured by the landmarks (Experiment 2). Conversely, when chronically unstable landmarks unexpectedly remained in place on catch trials, participants failed to notice and continued to navigate by path integration (Experiment 3). In the latter two cases, they gradually sensed the instability (or stability) of landmarks on later catch trials. These results demonstrate that path integration does not automatically serve as a back-up system, and does not function as a reference system on individual sorties, although it may contribute to monitoring environmental stability over time. Rather than being automatic, the roles of path integration and landmark navigation are thus dynamically modulated by the environmental context.

Optimal combination of environmental cues and path integration during navigation

“…However, other research has cast doubt on the idea that path integration functions as a backup system. Zhao and Warren (2015a) found that participants could not use path integration to perform a simple navigation task after previously visible environmental cues had been unexpectedly removed. On subsequent trials, however, participants were able to use path integration alone, indicating that they changed strategies after learning that environmental cues might not be completely reliable.…”

Non-Euclidean navigation

“…More importantly, path integration is not automatic and continuous, but intermittent and discontinuous. In an environment with stable visual landmarks for piloting, the path integrator actually shuts down, so the navigator is completely disoriented if landmarks unexpectedly vanish (Zhao and Warren, 2015a). Moreover, familiar visual landmarks act to reset the path integrator (both orientation and position) in humans (Mou and Zhang, 2014;Zhang and Mou, 2017;Zhao and Warren, 2015b) as in animals (Etienne et al, 2004;Knierim et al, 1998).…”

First Direct Evidence of Cue Integration in Reorientation: A New Paradigm

“…When there is a large discrepancy between feature and geometric cues, participants should choose between the conflicting cues (Cheng et al, 2007). We speculated that the switch from integration to choice might occur at 90 degrees, based on Ratliff and Newcombe (2008) and also on data on combining or choosing between landmarks and dead reckoning (Zhao & Warren, 2015).…”