Visual Homing Is Possible Without Landmarks: A Path Integration Study in Virtual Reality

Abstract

The literature often suggests that proprioceptive and especially vestibular cues are required for navigation and spatial orientation tasks involving rotations of the observer. To test this notion, we conducted a set of experiments in virtual environments in which only visual cues were provided. Participants had to execute turns, reproduce distances, or perform triangle completion tasks. Most experiments were performed in a simulated 3D field of blobs, thus restricting navigation strategies to path integration based on optic flow. For our experimental set-up (half-cylindrical 180 deg. projection screen), optic flow information alone proved to be sufficient for untrained participants to perform turns and reproduce distances with negligible systematic errors, irrespective of movement velocity. Path integration by optic flow was sufficient for homing by triangle completion, but homing distances were biased towards the mean response. Additional landmarks that were only temporarily available did not improve homing performance. However, navigation by stable, reliable landmarks led to almost perfect homing performance. Mental spatial ability test scores correlated positively with homing performance, especially for the more complex triangle completion tasks-suggesting that mental spatial abilities might be a determining factor for navigation performance. In summary, visual path integration without any vestibular or kinesthetic cues can be sufficient for elementary navigation tasks like rotations, translations, and triangle completion.

Do We Need to Walk for Effective Virtual Reality Navigation? Physical Rotations Alone May Suffice

“…There are, however, a few noteworthy exceptions where visual cues presented in immersive VR can be sufficient for spatial orientation tasks: When high visual realism is combined with an abundance of reliable landmarks and an immersive HMD or projection system, visual cues may be sufficient to enable excellent homing performance (Riecke, van Veen, & Bülthoff, 2002) as well as spatial updating performance that approaches real-world performance (Riecke, von der Heyde, & Bülthoff, 2005).…”

“…Many of these parameters have been shown to impact human spatial orientation performance (Riecke, Schulte-Pelkum, & Bülthoff, 2005;Riecke et al, 2002;Tan, Gergle, Scupelli, & Pausch, 2006Tan, Gergle, Scupelli, & R.Pausch, 2005;Alfano & Michel, 1990). Moreover, Ruddle and colleagues themselves had demonstrated that replacing an HMD with a desk-top monitor reduces navigation performance in VR, indicated by increased navigation times and less accurate sense of straight-line distances (Ruddle, Payne, & Jones, 1999).…”

Environmental stability modulates the role of path integration in human navigation

“…Note, however, that the rejection of landmarks in these experiments occurred after landmarks had been removed or displaced on multiple trials, creating an unstable environmental context. Riecke, van Veen, & Bülthoff (2002) similarly Page 8 of 48 reported homing by integration of optic flow when landmarks were replaced on multiple trials, although they did not provide idiothetic information. It is thus unknown if path integration served as reference system on the first such trial.…”

The development of multisensory balance, locomotion, orientation, and navigation

“…In a study with adults, Riecke et al (2002) separated the dual roles of vision in providing visual landmarks and optic flow by having subjects navigate in virtual reality through a field of visual 'blobs' that provided texture for optic flow but could not be used as landmarks.…”