Date of Degree

6-2022

Document Type

Thesis

Degree Name

M.S.

Program

Cognitive Neuroscience

Advisor

Tony Ro

Subject Categories

Cognition and Perception | Cognitive Psychology

Keywords

navigation, spatial memory, path integration, multimodal integration, cue conflict

Abstract

This study examined how humans respond to large 180º disparities between internally generated self-motion cues and external landmarks in a navigation task. Subjects learned the locations of 4 objects in a virtual environment, navigating back to these sites in a testing phase that probed their sense of direction at dead-ends. In select (incongruent) trials, subjects’ virtual rotations were mirrored relative to their physical turns, forcing them to navigate along separate virtual and physical trajectories. On these trials, subjects were either instructed to navigate using their memory of the required turn sequence (proprioceptive instructions) or the external environment (visual instructions).

Subjects fell into two categories based on whether they required clarification about how they should be orienting at endpoints in incongruent trials. The clarification group achieved higher accuracy under congruent conditions and appeared to prefer the visual modality in incongruent trials. This group performed similarly regardless of pathway geometry, and was more prone to modality discounting. The other group yielded higher errors in congruent conditions, performed differentially depending on pathway geometry, tended to place more weight on the proprioceptive modality, and was prone to modality averaging. Both groups modulated their modality weighting based on navigation instructions.

This study supports the position that human individuals employ different strategies when navigating under cue conflict conditions. It demonstrates that individuals who rely on visual landmarks commit smaller errors (and are less sensitive to trajectory shape) than individuals who rely on internal self-motion feedback when orienting, who also demonstrated greater propensity for cue averaging. These findings suggest that there may be individual differences in the internal representation of space, including how it is accessed and encoded online.

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