Abstract
Motor imagery (MI) is the mental rehearsal of movement, comprising visual and kinesthetic representations of the action. The independence of these imagery types (i.e., kinesthetic and visual MI) is unclear, specifically whether kinesthetic MI is possible without a visual representation? Moreover, their “functional equivalence” to representations governing movement execution is also questioned. Through a series of studies, we have investigated these questions by isolating visual and physical practice experiences and through measurement and manipulation of gaze during visual and kinesthetic MI. Across studies, participants imagined performing a series of hand gestures which were spatially manipulated while wearing an eye tracker or in a fixed space without an eye tracker. These imagery tasks were completed after visual-only, motor-only, or visual-motor practice (study dependent) and we measured subjective ratings of imagery quality as well as MI chronometry (difference between executed and imagined movement times). When gaze was tracked after visual-motor practice, both visual and kinesthetic MI involved task-related fixations and when gaze was centrally constrained, both MI chronometry and subjective ratings of both kinesthetic and visual imagery got worse. When vision was occluded during motor-only practice, chronometric measures of both kinesthetic and visual MI were adversely impacted, as compared to visual-only practice. These findings were robust for between- and within-participant investigations. Collectively, these studies support a visual-dependence hypothesis for MI, with kinesthetic MI relying on a visual representation. An additional study is underway to test this visual-dependency hypothesis when task-related proprioception is enhanced or impeded through manipulations to posture during imagery.
