Fitts law describes the effectiveness of the combined open and closed loop process that operate in these common actions. A formal informationtheoretic transmission scheme fitts julien gori, olivier rioul, yves guiard to cite this version. The authors purpose was to investigate if there is a speed accuracy trade off in soccer kicking by using instructions prioritizing velocity, accuracy, or both upon soccer kicking performance and kicking direction in experienced soccer players. Speedaccuracy tradeoffs in targetdirected movements. In addition, kinematics were measured to investigate the eventual differences in performance. Breaking down fitts law for ux designers ux planet. Speedaccuracy tradeoffs in targetdirected movements computer.
Fittss law is basically an empirical model explaining speedaccuracy tradeoff characteristics of human muscle movement with some analogy to shannons channel capacity theorem. An examination of the relationship between fitts law and. Tradeoffs have been shown to conform to the classical relationship known as fittss law fitts, 1954. For example, this law influenced the convention of making interactive buttons large especially on fingeroperated mobile devicessmaller buttons are more difficult and timeconsuming to click. Twopart models capture the impact of gain on pointing. This speedaccuracy tradeoff gets contribution from all the levels involved in the production of a fast movement, from motor planning to movement mechanics. Doyle 1division of engineering and applied science, california institute of technology. Speedaccuracy tradeoff an overview sciencedirect topics. Based on this hypothesis, we derive the ffitts modelan expansion and a refinement of fitts law for finger also touch input eq 2our study results show. Pdf human sensorimotor control exhibits remarkable speed and accuracy, as celebrated in fitts law for reaching.
Target clicking having proved an indispensable building block of interface design, it is little surprise that the speedaccuracy tradeoff of aimed movement has always been a keen concern of hci research. A sign of this conceptual hemineglect is visible in the recent iso standard 10, a set of guidelines for fitts law experimentation, which recommends to practitioners to. In the present study, a comparison is made between discrete versus cyclic aiming movements. Named the index of difficulty, d is the distance from the starting point to the center of the target. Fitts law models the speed accuracy tradeoff effect in pointing as imposed by the task parameters, through fitts index of difficulty i d based on the ratio of the nominal movement distance and the size of the target. The rationale for fitts law is that the pointing task has the informationtheoretic analogy of. Fitts law models the speedaccuracy tradeoff in untrained movements by establishing the existence of a linear relationship between a the time, mt, required to complete a discrete movement over different distances, d, to targets of different size, w, and.
Effects of age and gender on speed and accuracy of hand movements. Fitts law models the speedaccuracy tradeoff in untrained movements by establishing the existence of a linear relationship between a the time, mt, required to complete a discrete movement over different distances, d, to targets of different. The fitts tasks are considered to be spatially constrained, whereas the schmidt tasks are temporally constrained. Fitts law states that mt is constant whenever the ratio of the movement amplitude a and target width w remains constant. There are two prominent speed accuracy tradeoff relationships. Fitts law states that the amount of time required for a person to move a pointer to a target area is a function of the distance to the target divided by the size of the target. We introduce a new formulation of fitts law which specifies one sense in which the law can be said to be a speedaccuracy tradeoff, as. During the experiment the success rate in acquiring the target was displayed in the control room and communicated to the participant to provide feedback on their adherence to the speedaccuracy tradeoff governing fitts law. In a speed accuracy tradeoff, a low speed means higher accuracy. Note that, in contrast to fitts law, this equation links mt to parameters characterizing actual performance such as w e and d act, and the relationship is linear rather than logarithmic. A mathematical description of the speedaccuracy tradeoff. While doing experiments, by varying the speed accuracy criterion through instructions, payoffs, and deadlines, a person is able to respond quickly with many errors.
However, it is unknown whether the same law applies to cyclic aiming movements. Apr 23, 2015 this video explains the speed accuracy tradeoff and its relation to spatial accuracy and temporal accuracy. Pointing, input, speedaccuracy tradeoff, fitts law, modeling, human. Although there are some exceptions introduced in chapter 5 of your textbook, the general rule is. When both speed and accuracy are important, we commonly observe a phenomenon known as the speed accuracy tradeoff.
Fitts law models the speedaccuracy tradeoff effect in pointing as. Fullerton and cattell 1892 referenced some experimental work by both german and french investigators on the psychophysics of movement. Ken block drives the all new extreme e electric racecar in last stage of dakar rally duration. Fitts law describes a trade off between speed and accuracy for motor movement. A sign of this conceptual hemineglect is visible in the recent iso standard 10, a set of guidelines for fittslaw experimentation, which recommends to practitioners to. First, with the costbenefit tradeoff, the brain trades between the importance of moving faster toward a target that is more rewarding and the increased muscular cost resulting from a faster movement.
Although this explanation can provide a quantitative account of many aspects of motor variability, including fitts law, the fact that this law is frequently violated, e. This video explains the speedaccuracy tradeoff and its relation to spatial accuracy and temporal accuracy. Pointing tasks in humancomputer interaction obey certain speedaccuracy tradeoff rules. Effects of output display and controldisplay gain on human performance in interactive systems. Today, with the advent of graphical user interfaces and different styles of interaction, fitts law seems to have more importance than ever before. The time required for reaching a target of width w at distance d scales as log 2 2 dw 7,8. The landing point of a movement is randomly distributed, so the precision of the movement is reflected in the variability of the landing position. Effect of instructions prioritizing speed or accuracy on. This study aimed to verify the speedaccuracy tradeoff in individuals with cp. The goal of fittss index of performance pdf is to quantify the. Speedaccuracy tradeoffs in targetdirected movement have been studied for more than a century.
Speedaccuracy tradeoff in fitts law tasks researchgate. Speed accuracy trade off danielle festejo, brianna realin, nic remolona, adrian rivera dr. Speedaccuracy tradeoff in voluntary postural movements. The measurement of perceptual load in manual operations. Options to tradeoff scanning rate and accuracy might be expected to apply to saccades even in the absence of a difficult selection requirement because tradeoffs between speed and accuracy are characteristic of rapid aimed movements. In 1954, psychologist paul fitts, examining the human. Fitts law, throughput, speed accuracy tradeoff acm classification keywords h. Fitts throughput and the speedaccuracy tradeoff request pdf. The tradeoff between speed and accuracy for aiming movements has produced a very robust result in a large number of studies. The breakdown of fitts law in rapid, reciprocal aiming. Trading off speed and accuracy in rapid, goaldirected. Fitts law for speed accuracy tradeoff is a diversity sweet spot in sensorimotor control yorie nakahira 1. Fitt s law fitts came up with a mathematical principle concerning movement speed and accuracy.
In this experiment the relationship between these two speed accuracy tradeoffs was examined. Two basic tradeoffs interact while our brain decides how to move our body. A different type of speed accuracy tradeoff is reported when movement speed is imposed and spatial accuracy is to be maximized. Operating with different speed or accuracy biases, performers may utilize more or less area than the target specifies.
Fitts law models the speedaccuracy tradeoff effect in pointing as imposed by the task parameters, through fitts index of difficulty i d based on the ratio of the nominal movement distance and the size of the target. However, fitts law can also be realized as an emergent property of movements generated by delayed feedback. This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target. Abstractthe authors purpose was to investigate if there is a speed accuracy tradeoff in soccer kicking by using instructions prioritizing velocity, accuracy, or both upon soccer kicking performance and kicking direction in experienced soccer players. The characterization, often referred to as fitts law, stated that movement time is a logarithmic. In this case, an interesting question was whether the participants would be able to at least partially overcome the constraints of the speedaccuracy tradeoff, deviating from the predictions for movement times as imposed by fittss law. Fitts law, throughput, speedaccuracy tradeoff acm classification keywords h. Fitts law for speedaccuracy tradeoff is a diversity sweet spot in sensorimotor control yorie nakahira 1. This paper focuses on the predictive nature of the models. Methods participants continuous eeg data were recorded form 17 righthanded. Woodworth 1899 is often credited with being the founder of research on the speedaccuracy tradeoffs in movement. Oct 28, 2009 an intrinsic property of human motor behavior is a tradeoff between speed and accuracy.
Increasing the speed of movement reduces the precision of movement, whereas decreasing the speed of movement improves the precision of movement. Fitts law is widely applied in user experience ux and user interface ui design. Eeg correlates of fittss law during preparation for action. Estimation of psychomotor delay from the fitts law. Speedaccuracy tradeoff in planned arm movements with. An intrinsic property of human motor behavior is a tradeoff between speed and accuracy. While doing experiments, by varying the speedaccuracy criterion through instructions, payoffs, and deadlines, a person is able to respond quickly with many errors. Forty eight individuals with cp and 48 with typical development td were evaluated 32 females and 64 males with a mean age of 15. Fitts law literature has paid little or no attention to the variation of the speed accuracy balance, the transformation facet of the speed accuracy trade off. A mathematical description of the speedaccuracy tradeoff of. Request pdf speedaccuracy tradeoff in fitts law tasks on the equivalency of actual and nominal pointing precision abstract pointing. Jul 27, 2017 individuals with cerebral palsy cp present with sensorimotor dysfunction which make the control and execution of movements difficult. Fitts law has been widely used for more than half a century to quantify the human motor system fitts 1954. Trading off speed and accuracy in rapid, goaldirected movements.
Evaluation of speedaccuracy tradeoff in a computer task in. Based on this hypothesis, we derived the ffitts modelan expansion of. Second, with the speedaccuracy tradeoff, the brain trades between how accurate the movement needs to. Previous studies have allowed for the hypothesis that these two laws may be related or share. Investigation of speedaccuracy tradeoffs in speech. Linear and logarithmic speed accuracy tradeoffs in. Fittss law the glossary of human computer interaction. Frontiers unifying speedaccuracy tradeoff and cost. This paper is about fitts law, the wellknown relation that links the time it takes people to reach a target e. Fitts law states that the amount of time required for a person to move a pointer e. Accuracy was measured by recording the physical endpoints of each individual movement. Speedaccuracy tradeoff in fitts law tasks request pdf. Effects of age and sex on speed and accuracy of hand. Fitts law expresses the most well known relation of this tradeoff for spatially constrained movements fitts, 1954.
A group of 24 healthy participants made graphical pen movements in 12 different aiming tasks in which successive. Fitts law describes the tendency for a performer to trade speed for accuracy. Oct 12, 2010 options to tradeoff scanning rate and accuracy might be expected to apply to saccades even in the absence of a difficult selection requirement because tradeoffs between speed and accuracy are characteristic of rapid aimed movements. Fittss law and speedaccuracy tradeoffs during sequences of. In general, the more accurate the task to be accomplished, the longer it takes and vice versa. We refer to experimental settings in which the targets are imposed as distanceconstrained tasks cf. Pdf fitts law for speedaccuracy tradeoff is a diversity sweet spot.
Speedaccuracy tradeoff in fitts law taskson the equivalency of. Fittss law often cited as fitts law is a predictive model of human movement primarily used in humancomputer interaction and ergonomics. This is classically described by fitts law, a model derived by assuming that the human body has a limited capacity to transmit information in organizing motor behavior. Proceedings of the 18th annual conference of manual control. The width w and index of difficulty have an indirect relationship. A formal informationtheoretic transmission scheme fitts. Speed and accuracy in the learning of a complex motor skill. Fittss law and speedaccuracy tradeoffs during sequences. Fitts law describes a tradeoff between speed and accuracy for motor movement.
According to fitts law, there is speedaccuracy tradeoff in a wide variety of discrete aiming movements. According to fitts law, there is speed accuracy tradeoff in a wide variety of discrete aiming movements. Fittsas law and speedaccuracy tradeoffs during sequences. Rapid, targeted hand movements, that is, rapid movements of the hand into a specified target region, exhibit a regular movement pattern described by fitts law. Thus, the longer the distance and the smaller the targets size, the longer it takes. Fittss law is used to model the act of pointing, either by physically. Speedaccuracy tradeoff purpose to demonstrate the speedaccuracy tradeoff illustrated by fitts law. Options to tradeoff scanning rate and accuracy might be expected to apply to saccades even in the absence of a dif. The breakdown of fitts law in rapid, reciprocal aiming movements. The method of calculating fitts throughput is detailed, considering task characteristics, the speedaccuracy tradeoff, data collection, and data aggregation. In a speed accuracy trade off, a low speed means higher accuracy.
A group of 24 healthy participants made graphical pen movements in 12. Fitts law for speedaccuracy tradeoff is a diversity. In proceedings of the conference on human factors in computing systems chi08. Individuals with cerebral palsy cp present with sensorimotor dysfunction which make the control and execution of movements difficult. Relative effects of speedaccuracy emphasis on kindergarten. Fitts law for speedaccuracy tradeoff is a diversity sweet. Evaluation of speedaccuracy tradeoff in a computer task. Background the speedaccuracy tradeoff is one of the fundamental limitations of human movement control. Perspectives on 27 years of fitts law research in hci, int j humancomputer studies, 61. Fittslaw literature has paid little or no attention to the variation of the speedaccuracy balance, the transformation facet of the speedaccuracy tradeoff. Input devices and strategies introduction we explore an important but procedurally difficult tenet of fitts law. A different type of speed accuracy trade off is reported when movement speed is imposed and spatial accuracy is to be maximized. Fitts law is centered around a mathematical equation that is used to illustrate the time it takes to reach a target object.
1137 185 1607 1585 1130 296 603 466 129 306 40 1304 529 946 288 1655 872 1045 61 549 258 1408 1346 1084 279 1029 917 946 926 1376 51 393 884 945