different trade-offs between velocity and accuracy based on different theoretical principles ( Fitts, 1954 ; Plamondon & Alimi, 1997 ; Sherwood & Schmidt, 1980 ). For example, Fitts’ law ( 1954 ), based on principles of limited processing capacity, showed a logarithmic function between speed and accuracy
Mark L. Latash and Irina L. Mikaelian
We explored the relations between task difficulty and speech time in picture description tasks. Six native speakers of Mandarin Chinese (CH group) and six native speakers or Indo-European languages (IE group) produced quick and accurate verbal descriptions of pictures in a self-paced manner. The pictures always involved two objects, a plate and one of the three objects (a stick, a fork, or a knife) located and oriented differently with respect to the plate in different trials. An index of difficulty was assigned to each picture. CH group showed lower reaction time and much lower speech time. Speech time scaled linearly with the log-transformed index of difficulty in all subjects. The results suggest generality of Fitts’ law for movement and speech tasks, and possibly for other cognitive tasks as well. The differences between the CH and IE groups may be due to specific task features, differences in the grammatical rules of CH and IE languages, and possible use of tone for information transmission.
Marcos Duarte and Sandra M.S.F. Freitas
We investigated the speed and accuracy of fast voluntary movements performed by the whole body during standing. Adults stood on a force plate and performed rhythmic postural movements generating fore and back displacements of the center of pressure (shown as online visual feedback). We observed that for the same target distance, movement time increased with the ratio between target distance and target width, as predicted by Fitts’–type relationships. For different target distances, however, the linear regressions had different slopes. Instead, a single linear relation was observed for the effective target width versus mean movement speed. We discuss this finding as a result of the pronounced inherent variability of the postural control system and when such a source of variability is considered, the observed relationship can be explained. The results reveal that the accuracy of fast voluntary postural movements is deteriorated by the variability due to sway during standing.
Michael Bohan, Mitchell G. Longstaff, Arend W.A. Van Gemmert, Miya K. Rand, and George E. Stelmach
This study examined the impact of target geometry on the trajectories of rapid pointing movements. Participants performed a graphic point-to-point task using a pen on a digitizer tablet with targets and real time trajectories displayed on a computer screen. Circular- and elliptical-shaped targets were used in order to systematically vary the accuracy constraints along two dimensions. Consistent with Fitts' Law, movement time increased as target difficulty increased. Analysis of movement kinematics revealed different patterns for targets constrained by height (H) and width (W). When W was the constraining factor, movements of greater precision were characterized by a lower peak velocity and a longer deceleration phase, with trajectories that were aimed relatively farther away from the center of the target and were more variable across trials. This indicates an emphasis on reactive, sensory-based control. When H was the constraining factor, however, movements of greater precision were characterized by a longer acceleration phase, a lower peak velocity, and a longer deceleration phase. The initial trajectory was aimed closer to the center of the target, and the trajectory path across trials was more constrained. This suggests a greater reliance on both predictive and reactive control.
M.A. Urbin, David Stodden, Rhonda Boros, and David Shannon
The purpose of this study was to examine variability in overarm throwing velocity and spatial output error at various percentages of maximum to test the prediction of an inverted-U function as predicted by impulse-variability theory and a speed-accuracy trade-off as predicted by Fitts’ Law Thirty subjects (16 skilled, 14 unskilled) were instructed to throw a tennis ball at seven percentages of their maximum velocity (40–100%) in random order (9 trials per condition) at a target 30 feet away. Throwing velocity was measured with a radar gun and interpreted as an index of overall systemic power output. Within-subject throwing velocity variability was examined using within-subjects repeated-measures ANOVAs (7 repeated conditions) with built-in polynomial contrasts. Spatial error was analyzed using mixed model regression. Results indicated a quadratic fit with variability in throwing velocity increasing from 40% up to 60%, where it peaked, and then decreasing at each subsequent interval to maximum (p < .001, η2 = .555). There was no linear relationship between speed and accuracy. Overall, these data support the notion of an inverted-U function in overarm throwing velocity variability as both skilled and unskilled subjects approach maximum effort. However, these data do not support the notion of a speed-accuracy trade-off. The consistent demonstration of an inverted-U function associated with systemic power output variability indicates an enhanced capability to regulate aspects of force production and relative timing between segments as individuals approach maximum effort, even in a complex ballistic skill.
Alessia Longo and Ruud Meulenbroek
a single unit. Kelso demonstrated that the overriding tendency to generate synchronous movements in bimanual tasks by in-phase or antiphase coordination moderates Fitts’ law: Even when the movement distances and/or target widths for both hands differ, their MTs are not likely to deviate to the
Sergio L. Molina and David F. Stodden
practices of practitioners (e.g., physical educators, coaches, and other movement educators). Fitts’ law ( 1954 ) and its application, the speed-accuracy trade-off, are well-known principles that can be applied to many fundamental movements and performance ( Urbin, Stodden, Fischman, & Weimer, 2011
Marlowe Pecora, Luc Tremblay, and Matthew Heath
002219900218 10.1007/s002219900218 de Grosbois , J. , Heath , M. , & Tremblay , L. ( 2015 ). Augmented feedback influences upper limb reaching movement times but does not explain violations of Fitts’ law . Frontiers in Psychology, 6, 800 . PubMed ID: 26136703 doi:10.3389/fpsyg.2015.00800 10
Ran Zheng, Ilana D. Naiman, Jessica Skultety, Steven R. Passmore, Jim Lyons, and Cheryl M. Glazebrook
) experimental designs. In each task, there were two possible targets of different sizes and distances, with the same index of difficulty according to Fitts’ Law ( 1954 ). In the first task, participants moved along a track on a piece of Plexiglas® from the start position to one of the two targets, making it a
Scott Bonnette, Christopher A. DiCesare, Adam W. Kiefer, Michael A. Riley, Kim D. Barber Foss, Staci Thomas, Katie Kitchen, Jed A. Diekfuss, and Gregory D. Myer
-linear gaining in precision aiming: making Fitts’ task a bit easier . Acta Psychologica . 2008 ; 129 ( 2 ): 217 – 227 . PubMed ID: 18632086 doi:10.1016/j.actpsy.2008.06.001 18632086 10.1016/j.actpsy.2008.06.001 40. Kovacs A , Buchanan J , Shea C . Perceptual influences on Fitts’ law . Exp Brain Res