Future challenges for vection research: definitions, functional significance, measures, and neural bases

Abstract

This paper discusses four major challenges facing modern vection research. Challenge 1 (Defining Vection) outlines the different ways that vection has been defined in the literature and discusses their theoretical and experimental ramifications. The term vection is most often used to refer to visual illusions of self-motion induced in stationary observers (by moving, or simulating the motion of, the surrounding environment). However, vection is increasingly being used to also refer to non-visual illusions of self-motion, visually mediated self-motion perceptions, and even general subjective experiences (i.e., “feelings”) of self-motion. The common thread in all of these definitions is the conscious subjective experience of self-motion. Thus, Challenge 2 (Significance of Vection) tackles the crucial issue of whether such conscious experiences actually serve functional roles during self-motion (e.g., in terms of controlling or guiding the self-motion). After more than 100 years of vection research there has been surprisingly little investigation into its functional significance. Challenge 3 (Vection Measures) discusses the difficulties with existing subjective self-report measures of vection (particularly in the context of contemporary research), and proposes several more objective measures of vection based on recent empirical findings. Finally, Challenge 4 (Neural Basis) reviews the recent neuroimaging literature examining the neural basis of vection and discusses the hurdles still facing these investigations.

Vection and cybersickness generated by head-and-display motion in the Oculus Rift

“…However, HMDs allow (and even encourage) observer motion. Thus, the vection experienced while wearing an HMD is more appropriately defined as "visually-mediated self-motion perception" [38]. While visual motion should still be primarily responsible for inducing vection when wearing HMDs, head and body movements are also likely to contribute to this experience -both directly by stimulating the inertial self-motion senses (such as the vestibular system of the inner ear, the proprioceptive neck receptors, etc.)…”

Vection depends on perceived surface properties

“…Visual percepts of self-motion depend on the visual system's ability to compute heading and velocity in threedimensional (3-D) space from these two-dimensional (2-D) patterns of optic flow (see Lappe, Bremmer, & van den Berg, 1999, for a review). The importance of optic flow for selfmotion perception is evident in the fact that highly compelling illusions of self-motion can be induced in stationary observers by visual stimulation alone, traditionally known as vection (Dichgans & Brandt, 1978; for alternative definitions of this term, see Palmisano, Allison, Schira, & Barry, 2015). Most vection studies have used rather schematic dot motion displays to induce these illusions of self-motion.…”

Vection lies in the brain of the beholder: EEG parameters as an objective measurement of vection

“…Further, any conclusions drawn from vection research (theoretical or applied) are based on a series of assumptions all hinging on the interpretation of qualitative data. In a recent review paper, Palmisano et al (2015) emphasized the need for objective measurements of vection. In this paper we highlight EEG as a promising technique.…”