An optimal velocity for online limb-target regulation processes?
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.
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada. luc.tremblay@utoronto.ca.|Centre for Motor Control, University of Toronto, Toronto, ON, Canada. luc.tremblay@utoronto.ca.|, 55 Harbord St., Toronto, ON, M5S 2W6, Canada. luc.tremblay@utoronto.ca.
Luc
L
Tremblay
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada.
Valentin A
VA
Crainic
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada.
John
J
de Grosbois
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada.
Arindam
A
Bhattacharjee
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada.
Andrew
A
Kennedy
Centre for Motor Control, University of Toronto, Toronto, ON, Canada.|Schulich School of Education, Nipissing University, North Bay, ON, Canada.
Steve
S
Hansen
Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada.|Centre for Motor Control, University of Toronto, Toronto, ON, Canada.
Timothy N
TN
Welsh
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D013997:Time Factors; D034941:Upper Extremity / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*; D055815:Young Adult
Online control; Perception; Reaching; Target jump; Vision