Visual information throughout a reach determines endpoint precision

Abstract

People make rapid, goal-directed movements to interact with their environment. Because these movements have consequences, it is important to be able to control them with a high level of precision and accuracy. Our hypothesis is that vision guides rapid hand movements, thereby enhancing their accuracy and precision. To test this idea, we asked observers to point to a briefly presented target (110 ms). We measured the impact of visual information on endpoint precision by using a shutter to close off view of the hand 50, 110 and 250 ms into the reach. We found that precision was degraded if the view of the hand was restricted at any time during the reach, despite the fact that the target disappeared long before the reach was completed. We therefore conclude that vision keeps the hand on the planned trajectory. We then investigated the effects of a perturbation of target position during the reach. For these experiments, the target remained visible until the reach was completed. The target position was shifted at 110, 180 or 250 ms into the reach. Early shifts in target position were easily compensated for, but late shifts led to a shift in the mean position of the endpoints; observers pointed to the center of the two locations, as a kind of best bet on the position of the target. Visual information is used to guide the hand throughout a reach and has a significant impact on endpoint precision.

Upper Limb Asymmetries in the Matching of Proprioceptive Versus Visual Targets

“…Given that aiming tasks have been shown to rely heavily on visual information (Todor and Kyprie 1980), results reported by Flowers (1975) suggest an advantage for the preferred right arm in the utilization of visual feedback. In support of this conclusion, arm differences have also been demonstrated in the kinematics of visually guided aiming, especially in the case of deceleration duration, a period of time during which on-line corrections in movement trajectory based on visual feedback may occur (Carlton 1981;Elliott et al 1999a;Ma-Wyatt and McKee 2007). In this case, deceleration duration has been found to be shorter for the preferred arm (Boulinguez et al 2001;Elliott et al 1995;Mieschke et al 2001;Roy et al 1994;Todor and Cisneros 1985), suggesting a preferred-arm specialization for the more effective processing of visual feedback.…”

Visually guided pointing movements are driven by the salience map

“…For instance, with small movement targets (Fitts, 1954), it is possible to plan a slower but more accurate movement. However, visual feedback can also be used to control and change the movement trajectory during movement execution (Ma-Wyatt & McKee, 2007). Thus, it is possible that low-salience targets give rise to the planning of slower movements (compared to high-salience targets), and/or high-salience targets permit improved online control of the movement and thus faster movement execution.…”

“…Onset latencies were examined because these reflect processing prior to the overt pointing movement (Glover, 2004; see also Song & Nakayama, 2006, though we also analyzed the movement durations. Changes in movement time can stem from the (preparatory) planning stage of movement (Fitts, 1954;Glover, 2004), from processes that control and modulate the movement during its execution (Ma-Wyatt & McKee, 2007), and/or from modulations of movement trajectories (Song & Nakayama, 2006).…”

Continuous hand movement induces a far-hand bias in attentional priority

“…It is well established that our actions are strongly guided by visual perception: Activities such as reaching, grasping, and pointing to objects are performed more accurately and faster when they occur within our visual field and, in particular, when presented within the current focus of our visual attention (e.g., Adam, Buetti, & Kerzel, 2012b;Castiello, 1999;Ma-Wyatt & McKee, 2007). Effects of action on visual perception, in turn, are more subtle and have only recently been studied (e.g., Bekkering & Neggers, 2002;Fagioli, Hommel, & Schubotz, 2007;Vishton et al, 2007;Wohlschläger, 2000).…”