Visual regulation of manual aiming: A comparison of methods

Abstract

Visual regulation of upper limb movements occurs throughout the trajectory and is not confined to discrete control in the target area. Early control is based on the dynamic relationship between the limb, the target, and the environment. Despite robust outcome differences between protocols involving visual manipulations, it remains difficult to identify the kinematic events that characterize these differences. In this study, participants performed manual aiming movements with and without vision. We compared several traditional approaches to movement analysis with two new methods of quantifying online limb regulation. As expected, participants undershot the target and their movement endpoints were more variable when vision was not available. Although traditional measures such as reaction time, time after peak velocity, and the presence of discontinuities in acceleration were sensitive to the visual manipulation, measures quantifying the trial-to-trial spatial variability throughout the trajectory were the most effective in isolating the time course of online regulation.

Ageing of internal models: from a continuous to an intermittent proprioceptive control of movement

“…Indeed, although it was against an increased cognitive cost and additional neural resources, previous studies showed that older adults were able to reach levels of proprioceptive control of movement comparable to those of young adults (Batavia et al 1999;Boisgontier et al 2012;Deshpande et al 2003;Goble et al 2012a, b;Heuninckx et al 2008;Marks 1996;Pickard et al 2003). However, on the basis of the differences observed in motor imagery (Personnier et al 2010(Personnier et al , 2008Skoura et al 2005) and kinematic studies (Elliott and Hansen 2010;Goggin and Meeuwsen 1992;ReyRobert et al 2012; Seidler-Dobrin and Stelmach 1998), we hypothesised that (2) older adults were not able to reach the same level of end-point performance as the young adults in the fast speed condition due to the temporal constraints, making it impossible to use additional sub-movements to compensate for the presumably altered internal models. We also hypothesised that (3) older adults required a greater number of corrective sub-movements reflecting an intermittent control movement used to compensate for a presumed alteration of the internal models.…”

Different damping responses explain vertical endpoint error differences between visual conditions

“…Eliminating vision not only produced greater endpoint variability (Fig. 3b), as often observed in the literature Hondzinski and Cui 2006;Heath and Binsted 2007;Hondzinski and Kwon 2009;Elliott and Hansen 2010;Elliott et al 2014), it also accompanied a greater tendency to vertically undershoot remember target locations (Soechting and Flanders 1989b;Smetanin and Popov 1997;Henriques et al 1998;Crawford et al 2000;Henriques and Crawford 2002;Admiraal et al 2003;Wnuczko and Kennedy 2011;Elliott et al 2014) and endpoints achieved in the LIGHT condition (Soechting and Flanders 1989b;Flanders et al 1999;Hondzinski and Cui 2006;Wnuczko and Kennedy 2011;Hondzinski and Soebbing 2015). Undershooting in the dark occurred for each body orientation and starting arm position and corroborates evidence that movement excursions decrease for larger movement amplitudes when the arm is not visible (Bock and Eckmiller 1986) and that differences in endpoint precision between visual conditions occurs for targets requiring relatively large hand displacements (Henriques et al 2003;Hondzinski and Cui 2006).…”

“…Humans often use visual guidance to modify their performance when reaching or pointing to a seen target quickly and accurately (Chua and Elliott 1993;Elliott and Hansen 2010). Quick or slow goal-directed movements to visually remembered target locations often result in different endpoint locations when compared to reaching to veridical targets (Darling and Miller 1993;Westwood et al 2001;Heath and Westwood 2003;Heath et al 2004;Hondzinski and Cui 2006;Hondzinski and Kwon 2009).…”

Motor preparation and the effects of practice: Evidence from startle.

“…It has been suggested that changes in trial-to-trial movement variability best capture differences in modes of preparation (Elliott & Hansen, 2010) and thus we have included an analysis of withinsubject variability of the produced movement in startle trials as compared to control trials. We expected that advance preparation would be refiected by similar movement variability for both startle and control trials, as a similar movement should be released/ triggered after the go signal.…”