13 Apr Symmetrical Feedback Signals Agreement About Who Is In Control
One way to study the effects of motor sensorimo incongruity is the use of visceral feedbacks. When a mirror is placed perpendicular to the torso and a person places his arms on both sides, the hand in the mirror reflection seems to occupy the same room as the hand behind the mirror. The execution of symmetrical bilateral arm movements while looking at the reflected image makes the person feel as if he is looking at the hand behind the mirror and not the reflected image of the other hand. The incongruity between visual information and proprioceptive and motor signals may result from the participant observing the reflected image by making asymmetrical movements: the direction in which the arm appears to move will be contrary to the intended direction of movement and the direction in which the arm feels moving. Several studies have examined the effects of sensorimo motor incongruity by comparing reported limb reactions for participants who performed symmetrical and asymmetrical movements during visual feedback and control conditions in which the rearview mirror is removed or replaced with an opaque board [13-18]. Such subtle incongruity could result from slight differences in the elimination of individual limbs from the mirror or imperfect coordination of movements. Previous studies suggest that while the visibility of the contact site increases tactile sensitivity when the view and felt position of the affected area is in close orientation [36-39], misdirection of visual and proprioceptive information on one hand can reduce sensitivity by only a few centimetres. The RHI, which can move the felt position of the participant`s hand from its true position and to the position of a similarly oriented rubber hand , reduced attention to tactile stimulation of the manipulated hand relative to the participant`s other hand . Similarly, Folegatti and his colleagues  documented in two separate experiments of RT reduced to tactile stimulation using RHI and prismatic shift of vision to misalign the visual and proprioceptive representations of the hand. Finally, Tamé and his colleagues  demonstrated that moving the fingers of the hand image as seen by only four centimetres from the actual position of the participant`s finger reduced tactile performance in relation to visible and felt finger positions.