Effect of Variable Visual-Feedback Delay on Movement Time

2007 ◽  
Vol 51 (19) ◽  
pp. 1373-1377 ◽  
Author(s):  
Julio C. Mateo ◽  
Robert H. Gilkey ◽  
Jeffrey L. Cowgill
Keyword(s):  
Standard Deviation ◽  
Closed Loop ◽  
Movement Time ◽  
Three Dimensional ◽  
Feedback Delay ◽  
Fitts Law ◽  
Mean Delay ◽  
Delay Variability ◽  
The Mean ◽  
3D Virtual Environment

The effects of variable feedback delays on movement time were examined in a three-dimensional (3D) virtual environment. The participants' task was to use a 3D controller to position a cursor in targets as they appeared in a cubic workspace. Both the mean and standard deviation of the delay between the movement of the controller and the displayed position of the cursor were manipulated. In addition, the size of the targets and the distance between targets were varied. The results suggested that movement times are much more strongly affected by mean delay than by delay variability and that the effect of both variables is greatest during the closed-loop component of the movement. The results are discussed in relation to buffering strategies for reducing delay variability, Fitts' law, and other descriptions of aimed movements.

scholarly journals Quantification of Measurement and Model Effects in Monopile Foundation Scour Protection Experiments

2021 ◽  
Vol 9 (6) ◽  
pp. 585
Author(s):  
Minghao Wu ◽  
Leen De Vos ◽  
Carlos Emilio Arboleda Chavez ◽  
Vasiliki Stratigaki ◽  
Maximilian Streicher ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Flow Field ◽  
Three Dimensional ◽  
Small Scale ◽  
Maximum Wave Height ◽  
Chaotic Flow ◽  
The Mean ◽  
Scour Protection ◽  
Damage Number ◽  
Measurement Effects

The present work introduces an analysis of the measurement and model effects that exist in monopile scour protection experiments with repeated small scale tests. The damage erosion is calculated using the three dimensional global damage number S3D and subarea damage number S3D,i. Results show that the standard deviation of the global damage number σ(S3D)=0.257 and is approximately 20% of the mean S3D, and the standard deviation of the subarea damage number σ(S3D,i)=0.42 which can be up to 33% of the mean S3D. The irreproducible maximum wave height, chaotic flow field and non-repeatable armour layer construction are regarded as the main reasons for the occurrence of strong model effects. The measurement effects are limited to σ(S3D)=0.039 and σ(S3D,i)=0.083, which are minor compared to the model effects.

Foot Placement and Response Latency: A Test of Fitts' Law

1980 ◽  
Vol 24 (1) ◽  
pp. 626-628 ◽  
Author(s):  
Howard J Glaser ◽  
Charles G. Halcomb
Keyword(s):  
Response Latency ◽  
Movement Time ◽  
Three Dimensional ◽  
Vertical Plane ◽  
Brake Pedal ◽  
Lateral Separation ◽  
Response Latencies ◽  
Foot Placement ◽  
Fitts Law ◽  
Experimental Response

Response latencies were compared for three-dimensional brake/accelerator placements (depth, height, and lateral separation). Brake pedal width was found to be the only factor significantly affecting movement time. A comparison between Fitts' and Welford's movement time predictions and experimental response latencies resulted in correlations of .549 (p<.0001) and .543 (p<.0001). Neither movement time equations were able to predict response latencies when the brake pedal was placed 2.54 cm behind the vertical plane of the accelerator. Fitts' and Welford's equations are seen to have limited use in predicting three-dimensional foot movements.

Three-Dimensional Wheel Topography Measurement with Laser Triangulation

2012 ◽  
Vol 499 ◽  
pp. 384-389 ◽  
Author(s):  
Jia Liu ◽  
Wu Yi Chen ◽  
F. Chen
Keyword(s):  
Standard Deviation ◽  
Three Dimensional ◽  
Sampling Interval ◽  
Laser Triangulation ◽  
Evaluation Indexes ◽  
Wheel Topography ◽  
Sampling Intervals ◽  
Optimum Sampling ◽  
The Mean ◽  
Vitrified Cbn

Laser triangulation was used to measure the topography of vitrified CBN wheels and optimum sampling interval was obtained by comparing measuring results with different sampling intervals. Four evaluation indexes including the mean protrusion height of abrasive grains Hm, the standard deviation of grain protrusion height Hv, the standard deviation of the distance between two adjacent grains Dv and the number of micro cutting edges per square millimeter Nm were put forward to assess wheel topography and grinding performance. These indexes were verified to be effective by comparing 3D topography of newly manufactured wheel and dressed wheel.

Distribution of Movement Time in a Target-Aiming Task

1976 ◽  
Vol 43 (2) ◽  
pp. 507-513 ◽  
Author(s):  
Tarald O. Kvålseth
Keyword(s):  
Experimental Data ◽  
Standard Deviation ◽  
Normal Distribution ◽  
Linear Model ◽  
Movement Time ◽  
Arm Movements ◽  
Order Linear ◽  
First Order ◽  
Index Of Difficulty ◽  
The Mean

Various characteristics of the distribution of movement time were analyzed for a task involving serial and rotary arm movements aimed at a target. For experimental data generated from five Ss, (a) the distribution tended to be unimodal and more peaked than a normal distribution, (b) the skewness of the distribution was predominantly positive and (c) the standard deviation, in addition to the mean, of movement time was significantly affected by the complexity of the task as measured by Fitts' index of difficulty, while the skewness and the kurtosis were not. For the average results for the Ss, a first-order linear model with the standard deviation of movement time as the dependent variable and Fitts' index as the independent one explained 67% of the variation in standard deviation as compared to 98% of the variation in mean movement time accounted for by the Fitts' index.

A stopping time concerning sphere data and its applications

1996 ◽  
Vol 28 (03) ◽  
pp. 674-686
Author(s):  
Li-Xing Zhu ◽  
Ping Cheng ◽  
Gang Wei ◽  
Pei-De Shi
Keyword(s):  
Standard Deviation ◽  
Three Dimensional ◽  
Stopping Time ◽  
Tail Probability ◽  
Upper And Lower Bounds ◽  
Dimensional Sphere ◽  
Sphere Surface ◽  
Empirical Formulas ◽  
Iterated Logarithm ◽  
The Mean

Denote byA(x) = {a: |aτx| ≦h} a circle zone on the three-dimensional sphere surface for each givenh&gt; 0. For a given integerm, we investigate how many zones chosen randomly are needed to contain at least one of the points on the sphere surfacemtimes. As an application, the lifetime of a sphere roller is investigated. We present empirical formulas for the mean, standard deviation and distribution of the lifetime of the sphere roller. Furthermore, some limit behaviors of the above stopping time are obtained, such as the limit distribution, the law of the iterated logarithm, and the upper and lower bounds of the tail probability with the same convergent order.

scholarly journals Comparison of Fetal Nuchal Fold Thickness Measurements by Two- and Three-Dimensional Ultrasonography (3DXI Multislice View)

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Leonardo da Silva Valladão de Freitas ◽  
Fernanda Silveira de Bello Barros ◽  
Rômulo Negrini ◽  
Luiz Cláudio de Silva Bussamra ◽  
Edward Araujo Júnior ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Three Dimensional ◽  
Skin Surface ◽  
Cross Sectional Study ◽  
Rank Test ◽  
Cross Sectional ◽  
The Mean ◽  
The Difference ◽  
3D Ultrasonography ◽  
Thickness Measurements

Purpose. To compare the measurements of fetal nuchal fold (NF) thickness by two-dimensional (2D) and three-dimensional (3D) ultrasonography using the three-dimensional extended imaging (3DXI).Methods. A cross-sectional study was performed with 60 healthy pregnant women with a gestational age between 16 and 20 weeks and 6 days. The 2D-NF measurements were made as the distance from the outer skull bone to the outer skin surface in the transverse axial image in the suboccipital-bregmatic plane of the head. For the 3D we employed the 3DXI multislice view software, in which3×2tomographic planes was displayed on the screen and the distance between the tomographic slices was 0.5 mm. Maximum, minimum, mean, and standard deviation were calculated for 2D and 3D ultrasonography, as well the maximum and minimum, mean, and standard deviation for the difference between both methods. The Wilcoxon signed-rank test was used to compare the two different techniques.Results. 2D-NF showed a mean of thickness of3.52±0.95 mm (1.69–7.14). The mean of 3D-NF was3.90±1.02 mm (2.13–7.72). The mean difference between the methods was 0.38 mm, with a maximum difference of 3.12 mm.Conclusion. The NF thickness measurements obtained by 3D ultrasonography were significantly larger than those detected with 2D ultrasonography.

Conditions for a Linear Speed-Accuracy Trade-Off in Aimed Movements

1983 ◽  
Vol 35 (2) ◽  
pp. 279-296 ◽  
Author(s):  
Charles E. Wright ◽  
David E. Meyer
Keyword(s):  
Standard Deviation ◽  
Movement Time ◽  
Target Point ◽  
Home Position ◽  
Trade Off ◽  
Linear Speed ◽  
Temporal Precision ◽  
Fitts Law ◽  
Per Se ◽  
Speed Accuracy

A linear speed-accuracy trade-off has been found for rapid, precisely timed movements from a home position toward a target point. In this trade-off, We = K1 + K2(D/T), where D is the distance between the home position and the target, T is a pre-specified movement time, and We is the standard deviation of the distances actually moved. This result differs from Fitts' law, the commonly observed logarithmic trade-off in aimed movements. A new experiment with wrist rotations was performed to determine what conditions induce the linear trade-off rather than Fitts' law. Three types of condition are considered: movement brevity, feedback deprivation, and temporal precision. The experiment yielded a linear trade-off for precisely timed movements even when their durations significantly exceeded an amount of time (200 ms) sufficient to process visual feedback. This result suggests that the linearity does not depend on movement brevity and/or feedback deprivation per se. Instead it supports a temporal-precision hypothesis that the linear trade-off occurs when aimed movements must have precisely specified durations.

A stopping time concerning sphere data and its applications

1996 ◽  
Vol 28 (3) ◽  
pp. 674-686
Author(s):  
Li-Xing Zhu ◽  
Ping Cheng ◽  
Gang Wei ◽  
Pei-De Shi
Keyword(s):  
Standard Deviation ◽  
Three Dimensional ◽  
Stopping Time ◽  
Tail Probability ◽  
Upper And Lower Bounds ◽  
Dimensional Sphere ◽  
Sphere Surface ◽  
Empirical Formulas ◽  
Iterated Logarithm ◽  
The Mean

Denote by A(x) = {a: |aτx| ≦ h} a circle zone on the three-dimensional sphere surface for each given h > 0. For a given integer m, we investigate how many zones chosen randomly are needed to contain at least one of the points on the sphere surface m times. As an application, the lifetime of a sphere roller is investigated. We present empirical formulas for the mean, standard deviation and distribution of the lifetime of the sphere roller. Furthermore, some limit behaviors of the above stopping time are obtained, such as the limit distribution, the law of the iterated logarithm, and the upper and lower bounds of the tail probability with the same convergent order.

The angulation of the septal structures impacts ventricular imbalance in atrioventricular septal defects with a common atrioventricular junction

2015 ◽  
Vol 26 (2) ◽  
pp. 321-326 ◽  
Author(s):  
Zaheer Ahmad ◽  
Zek Lim ◽  
Kevin Roman ◽  
Marcus Haw ◽  
Robert H. Anderson ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Three Dimensional ◽  
Data Sets ◽  
Atrioventricular Septal Defects ◽  
Septal Defects ◽  
The Mean ◽  
Dimensional Echocardiography ◽  
Three Dimensional Echocardiography ◽  
Dimensional Assessment ◽  
Full Volume

AbstractObjectiveMultiplanar re-formatting of full-volume three-dimensional echocardiography data sets offers new insights into the morphology of atrioventricular septal defects. We hypothesised that distortion of the alignment between the atrial and ventricular septums results in imbalanced venous return to the ventricles, with consequent proportional ventricular hypoplasia.MethodsA single observer evaluated 31 patients, with a mean age of 52.09 months, standard deviation of 55, and with a range from 2 to 264 months, with atrioventricular septal defects, of whom 17 were boys. Ventricular imbalance, observed in nine patients, was determined by two-dimensional assessment, and confirmed at surgical inspection in selected cases when a univentricular strategy was undertaken. Offline analysis using multiplanar re-formatting was performed. A line was drawn though the length of the ventricular septum and a second line along the plane of the atrial septum, taking the angle between these two lines as the atrioventricular septal angle. We compared the angle between 22 patients with adequately sized ventricles, and those with ventricular imbalance undergoing univentricular repair.ResultsIn the 22 patients undergoing biventricular repair, the septal angle was 0 in 14 patients; the other eight patients having angles ranging from 1 to 36, with a mean angle of 7.4°, and standard deviation of 11.1°.The mean angle in the nine patients with ventricle imbalance was 28.6°, with a standard deviation of 3.04°, and with a range from 26 to 35°. Of those undergoing univentricular repair, two patients died, with angles of 26 and 30°, respectively.ConclusionsThe atrioventricular septal angle derived via multiplanar formatting gives important information regarding the degree of ventricular hypoplasia and imbalance. When this angle is above 25°, patients are likely to have ventricular imbalance requiring univentricular repair.

At Least One Standard Deviation Above the Mean

1969 ◽  
Vol 14 (9) ◽  
pp. 470-471
Author(s):  
M. DAVID MERRILL
Keyword(s):  
Standard Deviation ◽  
The Mean
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