Abstract
Does the nervous system make lasting corrections for inter-sensory mismatches? Conflicting answers to this question have been given. Research imposing a sensory mismatch has provided evidence that the nervous system realigns the senses, reducing the mismatch. At the same time, research exploiting natural inter-sensory biases provided evidence that the nervous system does not realign the senses. It is unclear whether this difference is due to a difference in experimental approach or whether corrections to natural and imposed mismatches are different. Here, we directly compare how the nervous system corrects for natural biases and imposed mismatches. Subjects moved a hand-held cube to virtual cubes appearing at random locations in 3D space. We alternated test blocks where subjects moved in complete darkness with feedback blocks where we rendered a cube based on the position of the hand-held cube. The first test block allowed us to measure natural biases, whereas subsequent test blocks allowed us to measure realignment to feedback. In feedback blocks, we imposed an eye-centered rotation of plus or minus five degrees on the visual feedback, creating a mismatch between vision and proprioception. We either provided feedback during the movement (continuous feedback) or after the movement had ended (terminal feedback). In this paradigm, endpoint errors are caused by a combination of natural biases and the imposed rotation. Taking advantage of the imposed rotations (-5, +5) canceling each other, we could decompose errors into a component in the direction of a subject’s natural bias and a component in the direction of the imposed rotation. We found that there was much more realignment for the imposed mismatch than for the natural biases. This difference in realignment was found with terminal as well as with continuous feedback. Thus, the nervous system corrects differently for imposed and natural mismatches.
Meeting abstract presented at VSS 2012