The role of vision and proprioception in self-motion encoding: An immersive virtual reality study

Past research on the advantages of multisensory input for remembering spatial information has mainly focused on memory for objects or surrounding environments. Less is known about the role of cue combination in memory for own body location in space. In a previous study, we investigated participants' accuracy in reproducing a rotation angle in a self-rotation task. Here, we focus on the memory aspect of the task. Participants had to rotate themselves back to a specified starting position in three different sensory conditions: a blind condition, a condition with disrupted proprioception, and a condition where both vision and proprioception were reliably available. To investigate the difference between encoding and storage phases of remembering proprioceptive information, rotation amplitude and recall delay were manipulated. The task was completed in a real testing room and in immersive virtual reality (IVR) simulations of the same environment. We found that proprioceptive accuracy is lower when vision is not available and that performance is generally less accurate in IVR. In reality conditions, the degree of rotation affected accuracy only in the blind condition, whereas in IVR, it caused more errors in both the blind condition and to a lesser degree when proprioception was disrupted. These results indicate an improvement in encoding own body location when vision and proprioception are optimally integrated. No reliable effect of delay was found.

Contributions of visual and proprioceptive information to travelled distance estimation during changing sensory congruencies

Recent research has provided evidence that visual and body-based cues (vestibular, proprioceptive and efference copy) are integrated using a weighted linear sum during walking and passive transport. However, little is known about the specific weighting of visual information when combined with proprioceptive inputs alone, in the absence of vestibular information about forward self-motion. Therefore, in this study, participants walked in place on a stationary treadmill while dynamic visual information was updated in real time via a head-mounted display. The task required participants to travel a predefined distance and subsequently match this distance by adjusting an egocentric, in-depth target using a game controller. Travelled distance information was provided either through visual cues alone, proprioceptive cues alone or both cues combined. In the combined cue condition, the relationship between the two cues was manipulated by either changing the visual gain across trials (0.7×, 1.0×, 1.4×; Exp. 1) or the proprioceptive gain across trials (0.7×, 1.0×, 1.4×; Exp. 2). Results demonstrated an overall higher weighting of proprioception over vision. These weights were scaled, however, as a function of which sensory input provided more stable information across trials. Specifically, when visual gain was constantly manipulated, proprioceptive weights were higher than when proprioceptive gain was constantly manipulated. These results therefore reveal interesting characteristics of cue-weighting within the context of unfolding spatio-temporal cue dynamics.