Biomechanical versus inertial information: Stable individual differences in perception of self-rotation.

Abstract

When turning without vision or audition, people tend to perceive their locomotion as a change in heading relative to objects in the remembered surroundings. Such perception of self-rotation depends on sensitivity to information for movement from biomechanical activity of the locomotor system or from inertial activation of the vestibular and postural systems. The authors report 3 experiments that investigated the relative contributions of biomechanical and inertial information to perceiving the speed of self-rotation. Using a circular treadmill, the proportions of the 2 sources of proprioceptive information were varied, creating walking conditions with a constant rate of biomechanical activity but with variable speeds of rotation relative to inertial space. The results reveal stable individual differences in sensitivity to information for the perception of locomotion. Just more than half of the participants based their perceived speed of self-rotation on biomechanical information, whereas the others based theirs on inertial information.

Integration of vestibular and proprioceptive signals for spatial updating

“…As an illustration, when participants were moved through space at a rate of 40°/s (vestibular cue), but walked at a rate of 56°/s (proprioceptive cue with a gain of 1.4 relative to vestibular cue), an average perceived rate of 48°/s was observed. These results are consistent with those of Bruggeman et al (2009) who found that participants perceived themselves to be moving faster when actively stepping through space (by turning around their vertical body axis) compared to stepping in place. When participants in their study stepped at one rate (10 rpm), but moved through space at another (e.g., 6 rpm), they perceived themselves as moving at approximately 7.5 rpm.…”

“…For instance, Kunz et al (2009) demonstrated that when comparing responses in an actual time-to-walk task (i.e., chronometric measure), to an imagined time-to-walk task, imagery was facilitated when observers simultaneously performed a behavior consistent with the imagined behavior (i.e., stepping in place) compared to an irrelevant behavior (i.e., waving one's arms). Further, several researchers have also reported that observers often experience a compelling sense of egocentric movement through space during relatively brief periods of blindfolded walking in place, which has been referred to as ''vection from walking'' (Becker et al 2002;Bles 1981;Bles and de Wit 1978;Bruggeman 2009). It should be noted that because curvilinear walking was used for the current study, it remains unclear whether such biases in updating would also be observed for other types of movements (e.g., purely translational or purely rotational).…”

“…It also maintains advantages over other methods that rely on the implicit assumption that participants have an accurate concept of units of measurements in degrees. For instance, some tasks require participants to use a button press or verbal response after rotating a certain number of degrees (Becker et al 2002;Bles 1981;Bles and de Wit 1978;Bruggeman et al 2009;Jürgens and Becker 2006;Marlinsky 1999). This is not as natural or intuitive as goal-directed target updating and requires additional transformations.…”

“…Far fewer studies, however, have systematically changed the relation between vestibular and proprioceptive cues when both are available during locomotion. Bruggeman et al (2009) introduced conflicts between proprioceptive and vestibular inputs while participants stepped around their earth-vertical body axis on a rotating platform by providing vestibular inputs that were slower than proprioceptive inputs. Specifically, participants always stepped at a rate of 10 rotations per minute (rpm) (constituting the proprioceptive input), but because the platform rotated in the opposite direction, participants were moved through space at various different rates (constituting the vestibular input).…”

Multisensory integration in the estimation of walked distances

“…More recently, others have introduced conflicts between proprioceptive and vestibular inputs while participants either stepped around their earth-vertical body axis (Bruggeman et al 2009) or when walking curvilinear paths through space (Frissen et al 2011). For instance, Frissen et al (2011) used a large circular treadmill, which featured a motorized handlebar that could move independently of the treadmill disc.…”