Measurement of instantaneous perceived self-motion using continuous pointing

Abstract

In order to optimally characterize full-body self-motion perception during passive translations, changes in perceived location, velocity, and acceleration must be quantiWed in real time and with high spatial resolution. Past methods have failed to eVectively measure these critical variables. Here, we introduce continuous pointing as a novel method with several advantages over previous methods. Participants point continuously to the mentally updated location of a previously viewed target during passive, full-body movement. High-precision motion-capture data of arm angle provide a measure of a participant's perceived location and, in turn, perceived velocity at every moment during a motion trajectory. In two experiments, linear movements were presented in the absence of vision by passively translating participants with a robotic wheelchair or an anthropomorphic robotic arm (MPI Motion Simulator). The movement proWles included constantvelocity trajectories, two successive movement intervals separated by a brief pause, and reversed-motion trajectories. Results indicate a steady decay in perceived velocity during constant-velocity travel and an attenuated response to mid-trial accelerations.

Multisensory integration in the estimation of walked distances

“…This has been shown in the context of travelled distance estimation for optic flow (Lappe et al 2007;Lappe and Frenz 2009) and during passive self-motion perception in the absence of vision (e.g. Siegle et al 2009). It may be the case that proprioceptive information provides an additional mechanism by which visual and vestibular information remains continuously calibrated with actual movement through space.…”

Integration of vestibular and proprioceptive signals for spatial updating

“…This unique instrument allowed us to manipulate the two signals independently during walking. We evaluated spatial updating using a continuous pointing task similar to that introduced by Campos et al (2009) and Siegle et al (2009), which expanded upon a paradigm originally developed by Loomis and et al (Fukusima et al 1997;Loomis et al 1992;Loomis and Philbeck 2008). This task involves continuous pointing to a previously viewed target during self-motion in the absence of vision.…”

“…For instance, various tasks have been used to assess performance under conditions in which observers actively walk through space (combined proprioceptive and vestibular inputs), walk in place (e.g., on a treadmill, producing proprioceptive but no vestibular inputs about linear translation), or are passively moved through space (vestibular inputs but no relevant proprioceptive information from the legs). Such studies have typically demonstrated that during simple, forward movement trajectories in the absence of vision, vestibular and proprioceptive information are each sufficient to estimate travelled distance (Berthoz et al 1995;Campos and Bülthoff (in press); Israël and Berthoz 1989;Harris et al 2000;Mittelstaedt and Mittelstaedt 2001;Loomis et al 1992;Loomis and Philbeck 2008;Siegle et al 2009;Sun et al 2004a, b) and to some extent self-velocity (Berthoz et al 1995;Campos et al 2009;Israël and Berthoz 1989;Siegle et al 2009). Further, vestibular information alone has been shown to be sufficient for estimating egocentric heading direction (Butler et al 2010;Fetsch et al 2009) and for estimating rotations around an earth-vertical axis (Becker et al 2002;Jürgens and Becker 2006).…”

Linear Path Integration Deficits in Patients with Abnormal Vestibular Afference

“…Future studies should also test a broader range of stimulus and response distances to increase the sensitivity of detecting path integration deficits. Furthermore, a passive wheelchair conveyance task (e.g., Allen et al , 2004) with continuous blind pointing (e.g., Siegle et al , 2009) to investigate linear path integration in UVH would corroborate these data.…”