Abstract
Precise knowledge of one’s limbs’ position in space is fundamental for goal-directed action. The brain’s representation of the body in space is thought to be generated through a process of multisensory integration of visual, tactile and proprioceptive signals. In this study, we devised a setup that allowed us to displace participants’ right hand without their subjective awareness. We accomplished this task by instructing the participants to view a live video feed of their hand from the first-person perspective. In the active condition, we used a sensorimotor illusion that caused the participants to actively but unknowingly displace their unseen right hand to a location 8 cm lateral to the image of their hand. In the passive condition, we mechanically displaced the participants’ hand—at a slow, unnoticeable velocity—to the same location. We found that during active displacement, the participants indicated that the location of their hand was closer to the digital image of the hand rather than the veridical location of the hand, as compared with the passive condition, in which the participants indicated that the locations of their hand were closer to the actual location. These results indicated that, compared with passive displacement, active movements cause greater recalibration of the hand’s spatial position and that the boosted spatial recalibration of hand position sense in the active task is driven by error-based sensorimotor corrections. These results have bearing on the perceptual mechanisms of recalibration of perceived limb location.
Highlights
Precise knowledge of the limbs’ position in space is fundamental for goal-directed action (Jeannerod et al 1995)
In a previous experiment conducted in our lab (Abdulkarim and Ehrsson 2016), we have examined the relationship between changes in hand position sense and the subjective feeling of ownership in the rubber hand illusion
We further used paired t tests to compare the specific conditions, and these comparison tests revealed a significant difference between the active movement and the passive movement conditions t(12) = 4.630, p = 0.001, d = 1.220
Summary
Precise knowledge of the limbs’ position in space is fundamental for goal-directed action (Jeannerod et al 1995). A similar recalibration of hand position sense that appears to occur without conscious awareness has been described in an interesting study by Newport and colleagues (Newport and Gilpin 2011) These authors have used a sensorimotor illusion in which the participants actively but unknowingly displaced their hand but perceived their hand to be in the original starting position. There is an interesting difference between our experimental results and those of Newport & Gilpin Both setups involve displacement of the participants’ real hand without their awareness, but in our setup, the displacement is induced passively by slowly moving the hand with a mechanical device and in Newport and Gilpin’s study, the displacement is performed actively by the participants themselves by an unconscious active visuomotor recalibration process. We obtained questionnaire data to verify that the participants were unaware of the experimental manipulations of hand position
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
