Abstract
Introduction. Elliott et al.'s multiple processes model of discrete reaching movements (2011) proposed two different forms of visually mediated online control (i.e., impulse regulation and limb-target regulation). Vision of the target is likely of greater importance for the limb-target regulation process than for the impulse regulation process. Recently, Tremblay et al., (2013) argued that impulse regulation may be better associated with measures of movement consistency (e.g., variable error: VE), whereas limb-target regulation should influence correlational measures of online control to a greater extent (e.g., Fisher2; de Grosbois & Tremblay, 2015). If this proposal is correct, then limb visibility should primarily influence VE while both the limb and target should be visible to influence Fisher2 values. Methods. Participants (n = 21) completed medial-to-lateral reaching movements in complete darkness. Limb and target visibility were mediated dim, green, light emitting diodes (LEDs). Each trial began with a preview of the finger location and a target location (i.e., either 10 or 30 cm away). Four vision conditions were employed by extinguishing LEDs, or not, upon movement initiation (i.e., limb-visible; target-visible; both visible; or neither visible). Results. Analyses of VE and Fisher2 in the primary movement axis were conducted as 2 Target x 2 Limb Visibility x 2 Target Visibility repeated measures ANOVAs. For VE, adding vision of the limb or the target both yielded better endpoint precision. For the Fisher2, adding vision of the target-only did not yield different correlation values. That is, the addition of target visibility decreased the Fisher2 values only when the limb was also visible. Conclusions. In the primary movement axis, correlational measures of online control (i.e., Fisher2) are specifically sensitive to limb-target regulation processes whereas endpoint precision measures (i.e., VE) are sensitive to all forms of online control. These results also further support the multiple processes model of online movement control.
Meeting abstract presented at VSS 2016