Purchase this article with an account.
Aaron Fath, Geoffrey Bingham; One thing at a time: Sequential coordination in visual guidance of locomotion-to-reach. Journal of Vision 2012;12(9):194. https://doi.org/10.1167/12.9.194.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The information and means of control that allow humans to locomote (Fajen & Warren, 2004) or reach (Anderson & Bingham, 2010) is well-studied, but less is known about the coordination of these actions when locomoting-to-reach. Anderson & Bingham (2010) proposed a new informational variable, hand-centric relative disparity tau, based on the evolution of relative binocular disparities of the hand and target over time. They also proposed a new control strategy, proportional rate control, that maintains informational variables in constant proportion with their own rates of change. In Anderson & Bingham (2011), participants locomoted to targets with outstretched hands and were found to use proportional rate control with head-centric tau to guide movement. Once hand-centric tau specified a time-to-contact less than that of the head-centric tau, participants applied proportional rate control to this now more conservative variable. In the current study, ten participants locomoted to a point-light target to place a point-light on their thumb beside the target. Participants performed 30 trials in each of two conditions: locomoting with an outstretched hand and initiating a reach to the target while locomoting. Results of the former condition replicated Anderson & Bingham (2011). In the latter condition, we hypothesized that head-centric tau would be used to initiate a "ballistic" reach, at the end of which head and arm/hand would form a rigid body, control then being switched from head-centric to hand-centric tau to bring the hand to the target using proportional rate control. Reach initiation was best predicted by head-centric tau, with an overall mean value of 0.92, and individual subjects were reliable, exhibiting an average standard deviation of 0.13. Overall, reaches had a mean duration of 530ms and terminated with 678ms actual time-to-contact. Upon termination, the hand was guided to the target using proportional rate control of disparity tau, as shown by regression analysis and model fits.
Meeting abstract presented at VSS 2012
This PDF is available to Subscribers Only