Manual interception of moving targets II. On-line control of overlapping submovements

Abstract

We studied the kinematic characteristics of arm movements and their relation to a stimulus moving with a wide range of velocity and acceleration. The target traveled at constant acceleration, constant deceleration, or constant velocity for 0.5-2.0 s, until it arrived at a location where it was required to be intercepted. For fast moving targets, subjects produced single movements with symmetrical, bell-shaped velocity profiles. In contrast, for slowly moving targets, hand velocity profiles displayed multiple peaks, which suggests a control mechanism that produces a series of discrete submovements according to characteristics of target motion. To analyze how temporal and spatial aspects of these submovements are influenced by target motion, we decomposed the vertical hand velocity profiles into bell-shaped velocity pulses according to the minimum-jerk model. The number of submovements was roughly proportional to the movement time, resulting in a relatively constant submovement frequency (approximately 2.5 Hz). On the other hand, the submovement onset asynchrony showed significantly more variability than the intersubmovement interval, indicating that the submovement onset was delayed more following a submovement with a longer duration. Examination of submovement amplitude and its relation to target motion revealed that the subjects achieved interception mainly by producing a series of submovements that would keep the displacement of the hand proportional to the first-order estimate of target position at the end of each submovement along the axis of hand movement. Finally, we did not find any evidence that information regarding target acceleration is properly utilized in the production of submovements.

Time-to-Contact Estimation of Accelerated Stimuli Is Based on First-Order Information.

“…If these results are in agreement with those reported within the perspective of Lee's (1976Lee's ( , 1980 work (Bootsma & Oudejans, 1993;Kaiser & Hecht, 1995;Lee et al, 1983Lee et al, , 1997Port et al, 1997;Ripoll & Latiri, 1997), then they underscore the robustness of the quantitative predictions for the use of a TTC1(x) strategy.…”

Minimum jerk for human catching movements in 3D

“…Thus, the hand velocity need not fall to zero between movement phases. The observed non-zero PMV is consistent with the superposition of two component sub-movements that overlap in time [22], [15].…”

Hitting a moving target: Perception and action in the timing of rapid interceptions

“…N. Lee, Young, Reddish, Lough, & Clayton, 1983;Peper, Bootsma, Mestre, & Bakker, 1994), and second, discrete error correction models similar in concept to those proposed for movements aimed at stationary targets (see, e.g., Elliott, Helsen, & Chua, 2001;Meyer et al, 1988), in which an initial preprogrammed movement is corrected by one or more subsequent discrete corrective submovements produced in response to perceptually detected errors in the unfolding movement (D. Lee et al, 1997;Tyldesley & Whiting, 1975). Of the two types, only continuous control has given rise to explicitly formulated models of interception that have been tested empirically.…”

“…For example, Montagne et al (1999) used a catching task, rather than a hitting task, that was performed using slow (peak speeds Ϸ 0.2 m/sec) movements of relatively long duration (MTs Ն 500 msec, approximately) in which the hand decelerated on approach to contact. Similarly, the interception task of Port and colleagues (D. Lee et al, 1997;Port, D. Lee, Dassonville, & Georgopoulos, 1997) involved slow-moving targets, the hand decelerating on approach to the interception location, and MTs in the approximate range of 500-1,800 msec (when corrective submovements were observed). In these circumstances, the Fitts-type strategy might be expected, since there is no need to move rapidly and there is time to use feedback.…”