Does changing Fitts’ index of difficulty evoke transitions in movement dynamics?

Huys, Raoul; Knol, Hester; Sleimen-Malkoun, Rita; Temprado, Jean-Jacques; Jirsa, Viktor K.

doi:10.1140/epjnbp/s40366-015-0022-4

Cited by 12 publications

(19 citation statements)

References 39 publications

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“…These results are consistent with those reported in previous studies using discrete Fitts' tasks (e.g., Temprado et al, 2013; Sleimen-Malkoun et al, 2013). In contrast to results observed for young adults (Huys et al, 2010, 2015; Vernooij et al, 2016), we did not find a breakpoint in the AT / DT ratio for elderly adults. A similar result was previously observed in discrete Fitts' task (Sleimen-Malkoun et al, 2013).…”

Section: Discussioncontrasting

confidence: 99%

“…In the present context, the absence of a breakpoint in AT / DT ratio in combination with the transition in behavioral dynamics (as indicated by phase flow analyses) is surprising since in previous studies changes in kinematic patterns and in dynamical regimes were considered to be closely related (Huys et al, 2010, 2015; Sleimen-Malkoun et al, 2013; Vernooij et al, 2016). The comparison between kinematic patterns and dynamical regimes in young and older adults suggest that these two levels of description of behavior are not systematically related, at least in older adults.…”

Section: Discussionmentioning

confidence: 52%

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The Effect of Aging on Muscular Dynamics Underlying Movement Patterns Changes

Vernooij

Rao

Berton

et al. 2016

Front. Aging Neurosci.

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Introduction: Aging leads to alterations not only within the complex subsystems of the neuro-musculo-skeletal system, but also in the coupling between them. Here, we studied how aging affects functional reorganizations that occur both within and between the behavioral and muscular levels, which must be coordinated to produce goal-directed movements. Using unimanual reciprocal Fitts' task, we examined the behavioral and muscular dynamics of older adults (74.4 ± 3.7 years) and compared them to those found for younger adults (23.2 ± 2.0 years).Methods: To achieve this objective, we manipulated the target size to trigger a phase transition in the behavioral regime and searched for concomitant signatures of a phase transition in the muscular coordination. Here, muscular coordination was derived by using the method of muscular synergy extraction. With this technique, we obtained functional muscular patterns through non-negative matrix factorization of the muscular signals followed by clustering the resulting synergies.Results: Older adults showed a phase transition in behavioral regime, although, in contrast to young participants, their kinematic profiles did not show a discontinuity. In parallel, muscular coordination displayed two typical signatures of a phase transition, that is, increased variability of coordination patterns and a reorganization of muscular synergies. Both signatures confirmed the existence of muscular reorganization in older adults, which is coupled with change in dynamical regime at behavioral level. However, relative to young adults, transition occurred at lower index of difficulty (ID) in older participants and the reorganization of muscular patterns lasted longer (over multiple IDs).Discussion: This implies that consistent changes occur in coordination processes across behavior and muscle. Furthermore, the repertoire of muscular patterns was reduced and somewhat modified for older adults, relative to young participants. This suggests that aging is not only related to changes in individual muscles (e.g., caused by dynapenia) but also in their coordination.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 52%

The Effect of Aging on Muscular Dynamics Underlying Movement Patterns Changes

Vernooij

Rao

Berton

et al. 2016

Front. Aging Neurosci.

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“…Subsequently the angle with the biggest value Θ max was retained. The biggest Θ max around the target (7 × 5 bins around the target location) was taken as a measure for the existence of a fixed point (fixed points were identified as Θ max > 90° 33 ).…”

Section: Methodsmentioning

confidence: 99%

Ebbinghaus figures that deceive the eye do not necessarily deceive the hand

Knol¹,

Huys²,

Sarrazin³

et al. 2017

Sci Rep

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In support of the visual stream dissociation hypothesis, which states that distinct visual streams serve vision-for-perception and vision-for-action, visual size illusions were reported over 20 years ago to ‘deceive the eye but not the hand’. Ever since, inconclusive results and contradictory interpretations have accumulated. Therefore, we investigated the effects of the Ebbinghaus figure on repetitive aiming movements with distinct dynamics. Participants performed a Fitts’ task in which Ebbinghaus figures served as targets. We systematically varied the three parameters which have been shown to influence the perceived size of the Ebbinghaus figure’s target circle, namely the size of the target, its distance to the context circles and the size of the context circles. This paper shows that movement is significantly affected by the context size, but, in contrast to perception, not by the other two parameters. This is especially prominent in the approach phase of the movement towards the target, regardless of the dynamics. To reconcile the findings, we argue that different informational variables are used for size perception and the visual control of movements irrespective of whether certain variables induce (perceptual) illusions.

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“…This phase transition has been demonstrated by phase flow analyses45, which have indicated the presence of fixed points at higher IDs only (see9 for a different method to identify phase transitions in Fitts’ task). Higher IDs are also associated with a modified endpoint kinematic pattern, as revealed by a decreased acceleration-to-deceleration ratio6.…”

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confidence: 92%

“…to (self-) organise into regimes to meet different task demands23. As an illustration, this approach allowed identifying pattern formation, at behavioural level, in a wide number of task paradigms, including Fitts’ task e.g 456…”

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confidence: 99%

Functional coordination of muscles underlying changes in behavioural dynamics

Vernooij

Rao

Perdikis

et al. 2016

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The dynamical systems approach addresses Bernstein’s degrees of freedom problem by assuming that the neuro-musculo-skeletal system transiently assembles and dismantles its components into functional units (or synergies) to meet task demands. Strikingly, little is known from a dynamical point of view about the functioning of the muscular sub-system in this process. To investigate the interaction between the dynamical organisation at muscular and behavioural levels, we searched for specific signatures of a phase transition in muscular coordination when a transition is displayed at the behavioural level. Our results provide evidence that, during Fitts’ task when behaviour switches to a different dynamical regime, muscular activation displays typical signatures of a phase transition; a reorganisation in muscular coordination patterns accompanied by a peak in the variability of muscle activation. This suggests that consistent changes occur in coordination processes across the different levels of description (i.e., behaviour and muscles). Specifically, in Fitts’ task, target size acts as a control parameter that induces a destabilisation and a reorganisation of coordination patterns at different levels of the neuro-musculo-skeletal system.

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Does changing Fitts’ index of difficulty evoke transitions in movement dynamics?

Cited by 12 publications

References 39 publications

The Effect of Aging on Muscular Dynamics Underlying Movement Patterns Changes

The Effect of Aging on Muscular Dynamics Underlying Movement Patterns Changes

Ebbinghaus figures that deceive the eye do not necessarily deceive the hand

Functional coordination of muscles underlying changes in behavioural dynamics

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