An optimal velocity for online limb-target regulation processes?

Abstract

The utilization of visual information for the control of ongoing voluntary limb movements has been investigated for more than a century. Recently, online sensorimotor processes for the control of upper-limb reaches were hypothesized to include a distinct process related to the comparison of limb and target positions (i.e., limb-target regulation processes: Elliott et al. in Psychol Bull 136:1023-1044. doi: 10.1037/a0020958 , 2010). In the current study, this hypothesis was tested by presenting participants with brief windows of vision (20 ms) when the real-time velocity of the reaching limb rose above selected velocity criteria. One experiment tested the perceptual judgments of endpoint bias (i.e., under- vs. over-shoot), and another experiment tested the shifts in endpoint distributions following an imperceptible target jump. Both experiments revealed that limb-target regulation processes take place at an optimal velocity or "sweet spot" between movement onset and peak limb velocity (i.e., 1.0 m/s with the employed movement amplitude and duration). In contrast with pseudo-continuous models of online control (e.g., Elliott et al. in Hum Mov Sci 10:393-418. doi: 10.1016/0167-9457(91)90013-N , 1991), humans likely optimize online limb-target regulation processes by gathering visual information at a rather limited period of time, well in advance of peak limb velocity.

Rapid online corrections for upper limb reaches to perturbed somatosensory targets: evidence for non-visual sensorimotor transformation processes

“…This result was taken as evidence for the pseudo-continuous use of visual feedback throughout the reaching trajectory (see also Elliott et al 1991). In the present study, our observation that correction latencies were not significantly altered by perturbation time when reaching to both visual and somatosensory targets may indicate that somatosensory information can be used in a pseudo-continuous manner at least in the first 200 ms of a movement lasting at least 500 ms (see also Tremblay et al 2017).…”

“…The change of target position required a change in movement direction (with consideration that movements are planned as a vector defined in terms of amplitude and direction; Buneo and Andersen 2006;Dadarlat et al 2015, Desmurget et al 1998. Offline analyses showed that the 100 ms perturbation time occurred prior to peak velocity, at a time during which visual information has been found to be important for online corrections (Kennedy et al, 2015;Tremblay et al, 2017). The 200 ms time roughly corresponded with the peak velocity of the aiming movements.…”

Continuously updating one’s predictions underlies successful interception

“…There are many studies that argue for a fundamentally different use of sensory information at different moments before and during an action, for instance on the basis of evidence that the moment at which visual information about the moving hand is provided matters (Kennedy et al 2015;Tremblay et al 2017), as does the time at which vision of the target is occluded (Brenner and Smeets 2011a;Sharp and Whiting 1974;Whiting and Sharp 1974). According to our proposal, providing information late during the movement is advantageous because as the hand approaches that target it is easier to anticipate errors.…”

Sensorimotor Learning during a Marksmanship Task in Immersive Virtual Reality

“…Whether this involves returning an overhand serve or putting on a pair of pants, a motor plan must be implemented and adjusted based on sensory feedback. The impact of sensory information in the motor process differs between two general components of movements: ballistic and refinement ( Desmurget and Grafton, 2000 ; Elliott et al, 2001 , 2010 ; Urbin et al, 2011 ). The action trajectory is initiated in a largely ballistic manner but becomes moderated by sensory feedback at some point, especially near its end ( Meyer et al, 1990 ; Khan and Franks, 2003 ).…”