The Role of Vision in the Control of Continuous Multijoint Movements

Abstract

The authors investigated whether visual fixations during a continuous graphical task were related to arm endpoint kinematics, joint motions, or joint control. The pattern of visual fixations across various shapes and the relationship between temporal and spatial events of the moving limb and visual fixations were assessed. Participants (N = 16) performed movements of varying shapes by rotating the shoulder and elbow joints in the transverse plane at a comfortable pace. Across shapes, eye movements consisted of a series of fixations, with the eyes leading the hand. Fixations were spatially related to modulation of joint motion and were temporally related to the portions of the movement where curvature was the highest. Gathering of information related to modulation of interactive torques arising from passive forces from movement of a linked system occurred when the velocity of the movement (a) was the lowest and (b) was ahead of the moving limb, suggesting that that information is used in a feedforward manner. Keywords coordination; limb control; oculomotor control Many of our daily activities involve coordinated motion of multiple body segments through the environment. Vision provides information about the environment, and that information is integrated with other sources of information regarding the effector's position so that we can achieve the movement goal. It is probable that the eyes move with a combination of smooth pursuit and saccadic movements. Researchers have shown that during movements that require precision, namely, identifying and preparing to manipulate objects, the eyes fixate and shift gaze several times so that they can gather information (Angel, Alston, & Garland, 1970;Biguer, Jeannerod, & Prablanc, 1982;Johansson, Westling, Backstrom, & Flanagan, 2001;Land, 1992;Land & McLeod, 2000;Land, Mennie, & Rusted, 1999;Neggers & Bekkering, 1999Pelisson, Prablanc, Goodale, & Jeannerod, 1986;Prablanc, Echallier, Komilis, & Jeannerod, 1979). For example, Johansson and colleagues investigated the coordination of eye saccades and hand movements in a functional goal-directed task. Participants had to grasp a bar, move it over an obstacle, and hit a target. Results demonstrated that participants consistently made saccades to distinct points, namely, the bar to be grasped and the target to be hit. Furthermore, participants did not saccade to the next position until the hand reached that current position (for the bar and the target). Thus, when participants were not given instructions with respect to eye movements in that goal-oriented task, their eyes made saccadic movements related to accurate control of the hand and did not make smooth pursuit movements. Specifically, the results of the cited research suggest that vision provides the central nervous system with information about the ongoing movement that is relevant to minimizing movement error and maximizing accuracy.

Implicit development of gaze strategies support motor improvements during action encoding training of prosthesis use

“…This may suggest a visual strategy related to the actuation of the prosthesis, which is opened by shoulder flexion and biscapular abduction. It is perhaps consistent with the use of focused vision on parts of seen action when joint control is most vital 24 . More needs to be understood about the role of gaze on body segments during action, specifically actions that require atypical patterns of motor control such as with prostheses.…”

A kinematic analysis of age-related changes in grasping to use and grasping to move common objects

“…In line with previous interpretations, our sample of elderly adults may compensate their real or perceived Table 1 Means and standard errors relative to the main effects. motor deficits using a 'play it safe' strategy (Welsh, Higgins, & Elliott, 2007) characterized by longer deceleration phases (Bennett & Castiello, 1994;Ketcham, Dounskaia, & Stelmach, 2006) and a more cautious grasping strategy that is less prone to errors such as misreaches or slipping of the objects (Holt et al, 2013). Alternatively, the reduced wrist rotation tendency in our sample could also be the secondary effect of a reduced flexibility in wrist motion as observed in elderly adults around the age of seventy (Carmeli et al, 2003).…”

Methodological aspects of EEG and body dynamics measurements during motion

“…Because there is a close relationship between vision and movement control, the synchronous analysis of gaze and motion plays an important role in current research (Ketcham et al, 2006 ; Heinen et al, 2012 ; Causer et al, 2013 ). Recently, Essig et al ( 2012 ) presented a modular approach to combine infrared MOCAP systems and mobile eye trackers for the analysis of the 3D gaze vector within the 3D MOCAP volume, while traditional eye trackers relate the gaze only to 2D video positions.…”