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Abstract

Optic flow is known to enable humans to estimate heading, translations, and rotations.
Here, we investigated whether optic flow simulating self-motions in virtual reality might also enable natural and intuitive spatial orientation, without the need for error-corrective feedback or training.
After visually displayed passive excursions along 1- or 2-segment paths, participants had to point toward the starting point "as accurately and quickly as possible".
Turning angles were announced in advance to obviate encoding errors due to misperceived turning angles. Nevertheless, many participants still produced surprisingly large systematic and random errors, and perceived task difficulty and response times were unexpectedly high.
Moreover, 11 of the 24 participants showed consistent qualitative errors, namely left-right reversals -- despite not misinterpreting the visually simulated motion direction.
Careful analysis suggests that some, but not all, of the left-right inversions can be explained by a failure to update visually displayed heading changes.
Left-right inversion was correlated with reduced mental spatial ability (corroborating earlier results), but not gender.
In conclusion, optic flow was clearly insufficient for enabling natural and intuitive spatial orientation or automatic spatial updating, even when advance information about turning angles was provided.
We posit that investigating qualitative errors for basic spatial orientation tasks using, e.g., point-to-origin paradigms can be a powerful tool for benchmarking VR setups from a human-centered perspective.