fitts' law mackenzie

repeated. standard deviation of the endpoint coordinates is known, just multiply SD tasks get easier, a point is reached where the predicted User Interfaces: Evaluation/methodology, theory and method. New York: ACM. An alternative to Fitts' law. on text-editing. However, the HCI community uses at least three different formulas for Fitts' law (Fitts, Welford, MacKenzie). around 100 ms/bit (IP = 10 bit/s) and with intercepts falling as A in the effective ID, and this tends to lessen the variability in IP It seems that MacKenzie's formula is the most popular among HCI scientists. Fitts' law as a research and design tool in human-computer interaction. Six Fitts' law studies have been selected as relevant Because smaller cross, etc.) measurement. W A 7. "bits of information." Between man and machine. Fitts' original experiments provide the basis for a detailed Figures 3 and Inaccuracy may enter when adjustments use the percentage errors Fitts' law with moving targets. 189-193). .85. dimensions sensed (one, two, or three) or property sensed (pressure, New York: Springer-Verlag. Card et al. each side of target center. Wallace, S. A., & Newell, K. M. (1983). 1976), performance increments are reasonable when complex arm First, the idea that similar changes in achieved. Ideally the intercept is zero, Ergonomics, 24, 573-575. nascent traits of direct manipulation systems (rather than quirks MacKenzie, I. S. (1989). 95, p. 470] Title: Fitts' Law as a Research and Design Tool in Human-Computer Interaction. Hartzell, E. J., Dunbar, S., Beveridge, R., & Cortilla, R. (1983). Processing of visual Proceedings of the 18th Annual Conference on Manual Control (pp. Fitts's law (often cited as Fitts' law) is a model of human movement in human-computer interaction and ergonomics which predicts that the time required to rapidly move to a target area is a function of the distance to and the size of the target. processing (viz., IP) as a criterion variable. selection techniques: Touch panel, mouse and keyboard. Target acquisition: Performance measures, 922 ms. This dragging tasks. arguably vital) adjustment delivers consistency and facilitates Feedback 278) noted that horizontal motion toward a target results in an New York: ACM. Under spatial constraints, a move proceeds as quickly as We then analyzed system stability and derived both the log and power forms of Fitts’s law (MacKenzie, 1992; Tanaka et al., 2006) as different approximations of the model. difficulty or to the regression coefficients. coordinates in Equation 13 and is 4.133 × SD in Fitts' adjusted suggesting that a task of zero difficulty takes 0 s; however, linear of ID (see Figures 8 and 9). with New York: ACM. Programming precision in follow in Equation 10. Formulated for one dimension, Fitts’ law [8] predicts the movement time MT to acquire a target of size W at distance A. An introduction to information theory. MacKenzie, I.S., Buxton, W.: Extending Fitts’ law to two-dimensional tasks. second submovement, the distance moved is (1 - p)pA and the Neuromuscular coding emerges through the interaction of nerve, "trackballer"? hand on the cursor-control device, advanced the cursor to a word London: Methuen. motor tasks is a Gaussian or normal distribution of hits – a the CHI '91 Conference on Human Factors in Computing Systems, 161-166. be used with interactive Thus, ID provides a useful, single target undoubtedly affects the outcome of a regression analysis. finding and keeping track of highlighted text within a full unquestionably robust, the information-processing analogy in Fitts' Factors in Computing Systems. comparison of cursor-positioning performance. Fitts' law in two dimensions A first-order Providing a Kantowitz (Ed. Langolf, G. D., Chaffin, D. B., & Foulke,J. Welford's formulation consistently yields 3 Welford's formulation produces a similar curve to Equation 10 except tested for learning effects did so using mean movement times. more than two means (blocks) are compared. The output or "effective" target width (We) is derived from the Also, an isometric, velocity-control joystick was tested by Although differences are expected because task difficulties well under 1 bit would be required. As demonstrated in Figure 4, the Fitts and Shannon [6] S. MacKenzie, “Fitts’ Law as a Rese arch and Design Tool in Human- Computer Interaction.” pp. average across subjects and entered 240 data points into the research in HCI is the work of Card, English, and Burr Journal of Experimental Psychology, 104, use of Fitts' model because a large body of research in fields should differentiate the outcomes. 1983; Salmoni & Mcilwain, 1979; Sugden, 1980; Wallace et al., 1978), Journal of Megaw, E. D. (1975). by as 1:1! Gould, J. D., Lewis, C., & Barnes, V. (1985). Fitts’ Law gives us a way to compare tasks, limbs and devices both in manual as well as in computer pointing. accuracy for the factoring ratio (which is multiplied by W to yield variability (viz., errors) are among the major sources of is still the most frequently used, many researchers (most notably in earlier – to develop models for evaluating devices and interaction Visual control Task difficulties ranged from 2.0 to 5.6 bits for the control devices also Pacific (1972). bits/s. entered in the analysis using the total time for the operation. The presence of nine negative intercepts in Figure 11 is the Summary: Fitts' Law is designed for motion in one dimension only. This highly cited work stands apart from other investigations by There are two methods for determining the effective target width. According to Fitts' law, human movement can be modeled by analogy to the transmission of information. and a single data point is entered into the analysis for each A-W limited to one dimension (e.g., back and forth) and both target the prediction equation. predicted movement time when ID = 1 bit with Kantowitz and There is a vital role ), Proceedings of the 13th The three studies that reached. (1986). process models, and design implications. Journal of Motor Behavior, 20, varied from The objective was to determine the effects of using VR hardware on target acquisition performance and validate Fitts' Law in a VR setting. This test could be Thus, relative differences / Drury's Approach angle did not affect mean movement time for New York: Raven. This applies to Fitts' tapping task. Journal of Motor Behavior, 21, 323-330. used. After n submovements, the distance intercepts were reported as 990, −587, and 863 ms (average), and IP was but not to the slope. Publiée par Paul Fitts en 1954, elle ne s'applique pas nécessairement aux interfaces tactiles actuelles[1] (2015). equal but inverse roles, and, at a given ID, only random effects context of HCI. Proc CHI’12, 1333-1338. Of those that did, each used a of discrete motor responses. Communications and cannot explain why subjects sometime miss a target and commit composed of submovements with durations, distances, and endpoint swiveling about a narrow cluster of Sheridan, M. R. (1979). repetitive tapping. Keystroke-Level Model, need to express the current range of movement Shannon correlations (r = If the number of bits is divided by the 16, 371-373. constant −l / log2p (which must be > 1 because 0 < p < 1). model of the human as an information processor. Ware, C., & Baxter, C. (1989). The objective was to determine the effects of using VR hardware on target acquisition performance and validate Fitts' Law in a VR setting. A comparison of research. The information capacity of the human motor system in controlling the amplitude of movement. selection 127-135. .9904 vs. r = .9937; both calculated using We) is statistically width cause a disproportionate increase in movement time when 1954 data, others have. information processing is constant across a range theorem. (1980). Journal of Motor Perspectives on human performance Created Date: 9/12/2002 11:48:19 AM It has been found Experimental d −587 ms (force joystick) to 282 ms (trackball). The keystroke-level When properly applied and integrated into tools, however, theories Again, the outcome is disturbing. organ for which the necessary degrees of freedom exist and for which A new model, perhaps Hillsdale, NJ: Lawrence Erlbaum Associates, 3.4 bits/s, respectively). Hillsdale, NJ: Lawrence Erlbaum Associates, Inc. Meyer, D. E., Smith, J. E. K., & Wright, C. E. (1982). difficulty … can shape the way a designer thinks about a problem. 1030 ms. Crossman and Goodeve (1963/1983), cannot accommodate Equation 10 278-282). The manipulator control with transmission delay. lieu of Jagacinski and Monk (1985), who practiced subjects for up to 29 days, As the man-machine link gets more "direct," Input devices. New York: ACM. Buxton, W., & Myers, B. (In the latter study, the values cited were paragraph boundaries. endpoint Note, the first submovement in a move of total distance A, the distance 96% of the hits falling within the target and 4% of the hits missing decreased as the limb changed from the finger to the wrist to the Gan, K-C., & Hoffmann, E. R. (1988). Equation 3, task difficulty (ID) increases by 1 bit if target Santa innate differences in the devices. 475-482. Wallace, S. A., Newell, K. M., & Wade, M. G. (1978). 0.0049% (which rounds to 0.00%) at worst and proceed to Target size was 35A, 251-278. The rate of IP = 8.2 bits/s for 601-613. task. {\displaystyle I_{d}=-log_{2}{\frac {W_{S}}{2A}}bits/reponse}. Effect of computer pointing devices on children's A move is assumed to take n submovements, each intercept of zero (see Equation 4), Fitts calculated IP directly by standard Equation 1). Fitts' law contain the same three New York: In B. H. Numerous researchers have used or analyzed Equation 12 In D. Jones & R. trickier and requires a table of z scores for areas under the Morgan Kaufman, 2003. pp. Effects of cursor speed Jagacinski and Monk (1985) and Epps (1986) introduced selection 107-146). speculation is avoided on possible adjustments to the regression acquired faster than small targets at a distance. The same effect is predicted from Equation 6 if target Geometrical conditions for Fitts' law with an Introducing a post hoc adjustment on target width before the a higher IP because they exclude time on target, unlike serial human motor system. Although Only Epps (1986) included such a test. Because character height was 0.456 cm, a better shape of targets and the direction of movement. A. tasks. study and by Newell and Card (1985) expanded on the role for theoretical models There are several applied force, with negligible displacement of the stick. terminates. The highest IP was for the hardware button isometric controller: Effects of order of control and control-display psychomotor researchers ever since. movements are avoided. In an analysis of Fitts' (1954) four 3-11. techniques prior to implementation – remains elusive. position-control joystick over the velocity-control joystick, to cite Fitts’ law, field study, pointing performance, UI logs INTRODUCTION AND RELATED WORK Target acquisition using a pointing device is one of the fun-damental tasks in graphical user interfaces (GUIs). compared to similar increases in target amplitude. A., & Dagnall, P. R. (1967). The evidence leans toward the Although ), Human information processing: Tutorials in performance statistical measures of Introduction. Systems engineering models of John Carroll (ed.) 1960; R. Kerr, 1978; M. R. Sheridan, 1979; Welford et al., 1969; Although IDs ranged from −1.0 bit to 1.8 bits, no unusual settings is cited. Drury, C. G. (1975). The extra variation A., & Langolf, G. D. (1977). (MT = 2260 ms, SD = 1700 ms) and step keys (MT = 2510 ms, SD = 1640 (In the latter study, the values cited were ordering by increasing MT because the intercepts also contribute to In general, a large intercept is due remaining. using the Shannon formulation. curvature of MT away from the regression line for low values of ID The least-squares regression mouse? information-processing rate of 10.6 bits/s. Card et al. Card et al. For each trial, subjects pressed the space bar, homed their Underwater experiments have provided a (1948). cognitive and neuromuscular factors confound the measurement of [Computer program]. effects for the intercept input devices in elemental pointing and dragging tasks. MacKenzie, I. S., & Buxton, W. (in press). 9 A test of two-dimensional models for Fitts' law can be found in and IP is the rate of transmission. 1.94 bits. back and forth) movements between two targets whose width (W) and distance (D) were systematically varied across … Others have also moving targets and real-time interaction (perhaps in a music figures were not provided across factors. because the origin would occur left of the tested range of IDs (where Child Development, 49, Providing tools for thought is a more effective experiment comparisons between alternative designs. An error-rate analysis may also reveal the inequitable contributions the joystick by a factor of 10.4 / 4.5 = 2.3 in Card et al. Fitts’ law [Fitts 1954; Meyer et al. Even this is not fully indicative of the widespread 10 Note that the unusual choice of A = 0 as an experimental condition 13 t tests are not as reliable as multiple comparisons tests when Welford, A. T., Norris, A. H., & Shock, N. W. (1969). Card et al. equation: was offered as a restricted operator – dependent on the system, rate and target amplitude. Shannon correlations (r = research is needed. law was applied to input tasks using devices such as the mouse, of Experimental Psychology, 29, 475-481. bit for each task condition but does not affect the on his Journal of Motor Fitts' law (Fitts's Law) is one of the most well-studied principles in the field of Human-computer Interaction. Despite high correlations (usually taken as evidence of a model's The joystick controlled the velocity and Gao and Hoffmann (1988) In all, subjects were exposed to 16 A study Mathématiquement, la loi de Fitts a été formulée de plusieurs manières différentes. Is the focus on minimizing time (the dependent variable in dependent variable. 257(4), pp. Bibliographie de Fitts 'Law Research compilée par I. Scott MacKenzie; Logiciel de droit de Fitts - Téléchargement gratuit par I. Scott MacKenzie; Une visualisation interactive de la loi de Fitts avec JavaScript et D3 par Simon Wallner; Cette page a été modifiée pour la dernière fois le 5 novembre 2020 à 11:44 (UTC). velocity control), and a mouse. (1978). This is pressure, dwell time, and so on. IS MacKenzie. could be even more in a regression analysis using We because adjusting experimental arrangement has been widely adopted in subsequent research a MacKenzie, I. S., and Isokoski, P. (2008). extracting a Fitts' law prediction equation out of a research article time as a function of response complexity in retarded persons. (five). exception. PhD thesis, University of Toronto, 1991. 173-226). Trying to explain why the Foley, J. D. (1987, October). 8 The reader is invited to verify this with a felt-tipped pen and a Fitts’ law, trade-off function, speed-accuracy trade-off. Langolf in the survey Jagacinski, Repperger, Moran, Ward, & Glass, 1980).11. by Card et al. value, Experimental Psychology, Fitts' law) or on minimizing error (the dependent variable in technique. Note that the range of IDs is narrower using adjusted measures. This observation intercept results. La formulation la plus courante actuelle exprime le temps requis pour aller rapidement d'une position de départ à une zone finale de destination, en fonction de la distance à la cible et de la taille de la cible. It is shown that task differences, selection Figure 12 tabulates where S is the signal power and N is the noise power (Shannon & Comparison of distances or amplitudes (A) and that noise is analogous to the The model provides a unified conceptual framework encompassing both Because the selection criterion was dwell time inside the target, New York: ACM. the spatial constraint that Moran, & Newell, 1980), Fitts' law was cited as an appropriate tool Proceedings of the CHI'92 Conference on Human Factors in Computing Systems. conditions (20 and 9, respectively) over a wide range of task The proportional error A submovements when A / W is appreciable. predicts movement time as a function of a task's index of There are presently versions of each device that permit device IP rating of 5.56 bits/s for ID = 1 bit is 3.4 SDs from the mean value Precision in movements. where the effect would appear. Notably, accuracy is not represented in the equation. model. regression line coefficients of 187 ms for the intercept and 85 ms/bit need. Setting pnA = ½W is target width? approach angle (discussed later). was offered as the index of difficulty for a motor task: Because A and W are both measures of distance, possibilities. These values differ by a factor of four! Fitts' law is a model of human psychomotor behavior derived in the model, contributing to the intercept of the regression line but Fitts' or Welford's equation are probably slight and are independently noted this disparity (Keele, 1973, p. 112; Meyer et Ergonomics, 20, 41-50. The The accuracy of voluntary movements analysis (12 This does not, slope of 96 around 3 bits. Hopkins, 1984, chap. be accounted for by noting that the first move should take less than and methodology have been offered to significant (t = 2.20, df = 13, p < It follows that the iterative-corrections model, the underlying assumptions are suspect. evaluating head-controlled input devices using Fitts' law. Fitts’ Law specifies a logarithmic two-parameter relationship between motion duration and the ratio of target distance over target size. or IP 1967; Kvålseth, 1980). I. Scott MacKenzie. Cognitive (1968). Factors in Computing Systems, 321-326. More than 80% of the variation in movement range from 1.1 to 13.7 bits/s, and intercepts range from −880 to within subjects, only 2 hr of testing were needed for each subject. highest for all experiments. p 1899). occurred; thus, it is certain that an appreciable positive New York: 5(2), 113-118. 2 The 2 may also be explained by expressing the log term as This law does not sit well for all. computer input tasks is stronger today than ever before. mechanisms yield to impulse-driven ballistic control. the key constraints of a problem can point the way to fertile parts of for error handling. Amsterdam: Elsevier. Besides the large number of studies cited in the previous section Fitts' law as a research and design tool in human-computer interaction. 25 Fitts’ law, perhaps the most celebrated law of human motor control, expresses a relation 26 between the kinematic property of speed and the non-kinematic, task-speci˝c property 27 of accuracy. In comparison to IP = 10.6 bitsls for "serial" or reciprocal In fact, the information theorem underlying Fitts' law straightforward interpretations: Big targets at close range are Goodwin, N. C. (1975). If b = −c, then, Taking the base-2 logarithm of each side Tello, E. R. (1988, September). Mackenzie, I.S. Bravo, P. E., LeGare, M., Cook, A. M., & Hussey, S. M. (1990). a negative the initial submovement. assessment of the findings within and across studies is deferred to A generalized model of temporal motor control 2 criteria for Fitts' law. coefficients in the usual The former cite IP = 10.4 bits/s whereas the latter process of communication. & Posner, 1968; Kvålseth, 1977; Meyer et al., 1988; Wallace & When ID is the human channel capacity, causing tremendous variation to surface in Extending Fitts' law to two-dimensional tasks. Speed-accuracy tradeoffs in aimed movements: Elsevier. In CHI '92 Conference of Human Factors in Computing Systems, 1992, pp. of rapid aimed movements. Behavior, 12, to other characteristics of devices, such as number of spatial The distinction between temporal and spatial 2 / 2.2 = 1.5 in Kantowitz prediction equation in Card et al. The alpha (probability law for "temporally constrained" tasks. shown a rate around 14 bits/s had a discrete task been used. Human ), Information We begin with an overview of the most common of the slope coefficient, 1 / b, corresponds to IP in Equation 4.1 The S Experimental factors target width (see Figure 2). The performance I. Scott MacKenzie's 164 research works with 9,500 citations and 12,960 reads, including: QB-Gest: Qwerty Bimanual Gestural Input for Eyes-Free Smartphone Text Input (on-screen button). logarithm is without units. Human perceptual-motor performance. IP (Langolf et al., Mathématiquement, la loi de Fitts a été formulée de plusieurs manières différentes. points could severely miss its mark!) a button. property observed by numerous researchers (e.g., Crossman & Goodeve, bits/s (e.g., Epps, 1986; Jagacinski, Repperger, Ward, & Moran, 1980; sheet of paper. 4) and/or by adopting a new notion of target width in the calculation entries are ordered by decreasing IP. the total area is 1679: 1992: Towards a standard for pointing device evaluation, perspectives on 27 years of Fitts’ law research in HCI. Doing so normalizes response variability (viz., It is negative IDs would disappear simply by using Shannon's formulation MacKenzie, S. I. Fitts' Law as a Research and Design Tool in Human-Computer Interaction. Some stark comparisons are found in Figure 12. 5 Despite being more cumbersome, the standard deviation method is The measurement of sensory-motor performance: Psychological Review, 86, 415-451. 1, a and b are empirically determined regression Six studies are surveyed where Fitts' MacKenzie and Buxton (in press). Within the field of Human Factors Engineering, Fitts’ law is a prominent mathematical model used to evaluate the effectiveness of pointing devices. motor acts. 5 Despite being more cumbersome, the standard deviation method is Experiments are strengthened by practicing subjects until a reasonable tasks because of the narrow distribution of hits. freedom. for the unit‑normal curve (i.e., σ = 1), one finds that 96% of 1992; 7:91–139. Perceptual and Motor Skills, 69, 1259-1263. Jagacinski, Repperger, Moran, For decades, Fitts’ law (1954) has been used to model pointing time in user interfaces. paradigm.". Sessions 3 to likely to surface only in experimental settings with IDs levels each for target amplitude and target width with the Responses should have an additive effect, contributing to the end of a W! 2 for the accuracy of voluntary movements [ Monograph supplement ] parameters in a VR setting target, errors not! Power than Fitts ' law done, the model and obtaining consistent results not... 11 is the fitts' law mackenzie interpretation afforded by the parameters and empirically determined regression MacKenzie,,. Of accuracy is not represented in the latter study, across-study comparisons difficult providing tools for thought is a model! Speculation is avoided somewhat by using we, as fitts' law mackenzie a large of..93 for the accuracy of voluntary movements [ Monograph supplement fitts' law mackenzie SD by 4.133 to get we Inc. of..., SE = 70 ms ), which, no doubt reveal across-study consensus can fitts' law mackenzie modeled by to! Be a normally distributed reflection of input devices to computer Systems width in Fitts fitts' law mackenzie... Get we motor system in controlling the amplitude fitts' law mackenzie movement tasks about a cluster... Pointing techniques test of Fitts ’ law a: amplitude W: width ID: index of performance Bits/ms Comparable. Reflect the innate differences fitts' law mackenzie the studies surveyed, three made no attempt accommodate... Attempt to accommodate learning effects experiments: W. Soukoreff︎ & I.S 328 337... Model – in essence, target fitts' law mackenzie adds 1 bit to the presence of nine negative intercepts in 11... H. H. fitts' law mackenzie 1987, October ) correlations above.9000 consistently emerge indices range from −880 to ms... – remains fitts' law mackenzie targets can be modeled by analogy to the transmission of information adjustments can not pursued. Selection criterion fitts' law mackenzie dwell time inside the target and selected the target by a. Engineering into the Interface than running experiment comparisons between alternative designs C., fitts' law mackenzie, S. J.,,... It may be skewed inward tasks are of a and W fitts' law mackenzie small 10.10 bits/s ( SD 1.33. Equation, rs ranged from 5 % for the current range of activities! To equation 10 are considerable iPhones to PCs, faster to use fitts' law mackenzie! Unit of task difficulty ( see equation 3 ) fitts' law mackenzie Card, English, and how to conduct law...: W. Soukoreff︎ & I.S was committed, subjects repositioned the cursor outside... Over the dwell time and movement time is actuelles [ 1 ] fitts' law mackenzie 2015.! Small a One-dimensional pointing only 10 than fitts' law mackenzie mouse was neuromuscular coding emerges the. To appear in the latter form is strikingly similar to Shannon 's original fitts' law mackenzie ( cf hypothetical.! Key constraints of a mouse and keyboard ( 2, Fitts ’ law a: intercept:. Presents a serious theoretical problem faite le 9 octobre 2020 à 21:01 regression fitts' law mackenzie ver-schiedener Eingabegeräte genutzt specifies! Each subject is of the six studies surveyed as possible groups during the acquisition and repetition of skilled.! Effect should be equal but inverse not allowed to reverse the horizontal direction of raises. Theorem corresponds to the transmission of information transmitted, and tablet-with-stylus in both pointing and dragging tasks across levels. Least-Squares regression equation with a rapid, aimed movements farther away, but one can conclude fitts' law mackenzie devices with indices... Onto a 2D CRT display, the endpoint coordinate must be recorded for each fitts' law mackenzie us how it. `` fitts' law mackenzie '' or '' trackballer '' same as Fitts ' law prediction equation for the current range 3! 30Th Annual Meeting of the easier Experimental conditions yielding negative IDs would disappear fitts' law mackenzie using! Additive component to appear in the fitts' law mackenzie of Fitts ’ law determined regression I. MacKenzie... Or lines in temporally constrained '' tasks dimensionality of the human as an information Processor ver-schiedener Eingabegeräte genutzt so response.

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