Information capacity of discrete motor responses.

Fitts, Paul M.; Peterson, James R.

doi:10.1037/h0045689

Cited by 1,296 publications

(743 citation statements)

References 16 publications

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“…5; hitting back later corresponds to negative values, where the vertical extent of the shaded area is smaller). The optimal speed for intercepting a target is one that finds the right balance (Brouwer et al 2000) between moving slowly to improve the spatial resolution (Fitts and Peterson 1964) and moving fast to improve the temporal resolution (Schmidt 1969). The fact that the disk had to pass through the goal probably forced our subjects to move faster than would be optimal for hitting a chosen spot on the target's edge.…”

Section: The Strategymentioning

confidence: 99%

Sources of variability in interceptive movements

Brenner

Smeets

2009

Exp Brain Res

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In order to successfully intercept a moving target one must be at the right place at the right time. But simply being there is seldom enough. One usually needs to make contact in a certain manner, for instance to hit the target in a certain direction. How this is best achieved depends on the exact task, but to get an idea of what factors may limit performance we asked people to hit a moving virtual disk through a virtual goal, and analysed the spatial and temporal variability in the way in which they did so. We estimated that for our task the standard deviations in timing and spatial accuracy are about 20 ms and 5 mm. Additional variability arises from individual movements being planned slightly differently and being adjusted during execution. We argue that the way that our subjects moved was precisely tailored to the task demands, and that the movement accuracy is not only limited by the muscles and their activation, but also-and probably even mainlyby the resolution of visual perception.

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Section: The Strategymentioning

confidence: 99%

Sources of variability in interceptive movements

Brenner

Smeets

2009

Exp Brain Res

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“…The relationship between these two variables has been formalized as Fitts' law. 23,24 It states that movement time (MT) is a linear function of the index of difficulty (ID ¼ Log2 [2A/W]), where A is the amplitude of the movement and W the width of the target (accuracy constraint).…”

Section: Introductionmentioning

confidence: 99%

Influence of obesity on accurate and rapid arm movement performed from a standing posture

Berrigan

Simoneau

Tremblay³

et al. 2006

Int J Obes

104

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Introduction: Obesity yields a decreased postural stability. The potentially negative impact of obesity on the control of upper limb movements, however, has not been documented. This study sought to examine if obesity imposes an additional balance control constraint limiting the speed and accuracy with which an upper limb goal-directed movement performed from an upright standing position can be executed. Method: Eight healthy lean subjects (body mass index (BMI) between 20.9 and 25.0 kg/m 2 ) and nine healthy obese subjects (BMI between 30.5 and 48.6 kg/m 2 ) pointed to a target located in front of them from an upright standing posture. The task was to aim at the target as fast and as precisely as possible after an auditory signal. The difficulty of the task was varied by using different target sizes (0.5, 1.0, 2.5 and 5.0 cm width). Hand movement time (MT) and velocity profiles were measured to quantify the aiming. Centre of pressure and segmental kinematics were analysed to document postural stability. Results: When aiming, the forward centre of pressure (CP) displacement was greater for the obese group than for the normal BMI group (4.6 and 1.9 cm, respectively). For the obese group, a decrease in the target size was associated with an increase in backward CP displacement and CP peak speed whereas for the normal BMI group backward CP displacements and CP peak speed were about the same across all target sizes. Obese participants aimed at the target moving their whole body forward whereas the normal BMI subjects predominantly made an elbow extension and shoulder flexion. For both groups, MT increased with a decreasing target size. Compare to the normal BMI group, this effect was exacerbated for the obese group. For the two smallest targets, movements were on average 115 and 145 ms slower for the obese than for the normal BMI group suggesting that obesity added a balance constraint and limited the speed with which an accurate movement could be done. Summary: Obesity, because of its effects on the control of balance, also imposes constraints on goal-directed movements. From a clinical perspective, obese individuals might be less efficient and more at risk of injuries than normal weight individuals in a large number of work tasks and daily activities requiring upper limb movements performed from an upright standing position.

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“…There have been some previous attempts to address this issue. In his original study, Fitts reported the reaction times in addition to the movement times recorded in a repetitive tapping task (Fitts 1954;Fitts & Peterson 1964). The results suggested that RT was influenced by the task constraints but the relationship was weak.…”

Section: Introductionmentioning

confidence: 99%

The effect of distance on reaction time in aiming movements

et al. 2007

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Target distance affects movement duration in aiming tasks but its effect on reaction time is poorly documented. RT is a function of both preparation and initiation. Experiment 1 precued movement (allowing advanced preparation) and found no influence of distance on RT.Thus, target distance does not affect initiation time. Experiment 2 removed pre-cue information and found that preparing a movement of increased distance lengthens RT.Experiment 3 explored movements to targets of cued size at non-cued distances and found size altered peak speed and movement duration but RT was influenced by distance alone.Thus, amplitude influences preparation time (for reasons other than altered duration) but not initiation time. We hypothesise that the RT distance effect might be due to the increased number of possible trajectories associated with further targets: a hypothesis that can be tested in future experiments.

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Information capacity of discrete motor responses.

Cited by 1,296 publications

References 16 publications

Sources of variability in interceptive movements

Sources of variability in interceptive movements

Influence of obesity on accurate and rapid arm movement performed from a standing posture

The effect of distance on reaction time in aiming movements

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