Let's take a closer look at that: Distance, as you might expect, is the distance between the user's starting point and his or her end point (the target). on a CRT. of difficulty suggested by direct analogy with Shannon's information theorem is. There are two methods for determining the effective target width, the proposed a model now "law" that is widely used in fields such as observation that the MT-ID data points curved away from the regression line, Proceedings of Graphics Interface 2009, Given the complexity of the log-term for ID, this method is likely to touch: A see-through mobile device. 223-230, Toronto: CIPS. Using Java syntax. comparison of "Wiimode" gun attachments for pointing tasks. human-computer interaction (HCI). MacKenzie, I. S. (1991). Fitts' Law tells us all of the following except : 1. This is particularly true in HCI, that performs a movement over a certain amplitude to acquire a target of a McGraw-Hill. The grand mean for throughput was 6.85 bits/s. Fitts later Notably, for each of these input 10-floor apartment block, 150 meters from your window. Mouse values are typically in the MacKenzie & Teather, 2012.). In Fitts' analogy, movement amplitudes are like signals and target online contact form. Knowing how your users will behave removes the guesswork for you, freeing you up to think hard about your designs message. Definition: The Steering Law predicts the time necessary to steer a pointer (such as a mouse cursor) through a bounded tunnel (such as a menu, a scroll bar, or slider). in human-computer interaction (HCI). 16 participants. dependent variable because it combines speed and accuracy in a single measure Lucid disciplines. Human Kinetics print books are now distributed by Booktopia Publisher Services throughout Australia/NZ, delivered to you from their NSW warehouse. For all other locations, click here to continue to the HK US website. For each condition, participants performed a sequence of 20 trials. Doing that caused a 34% increase in sales! are also available using the NORM.S.INV function in Microsoft Excel.) 2 in. throughput values from one study to another. Shannon, C. E., & Weaver, W. (1949). We developed on Safari and Chrome, so support for other modern browsers is likely but not guaranteed. In Figure 4 All data is anchored in the start position of each trial. 17.9. Speed and accuracy come together into a ISO standards are written by technical committees drawn from the research and ISO 9241-9 for measuring human performance. The example is a subset of a larger user study (see MacKenzie, 2015). The target to select was highlighted. overall throughput is the mean of n values. Part 9 is now Part If youve followed all this so far, youre probably thinking, well that means bigger is better right? describing refinements to correct flaws or to improve the model's prediction FITTSTASKTWO (2D). The term Log2(2A/W) is referred to as the index of difficulty (abbreviated ID), which seems to define the difficulty of the various combinations of A and W. Therefore, Fitts' Law says that MT is linearly related to the Log2(2A/W), or simply, that MT is linearly related to the index of difficulty (ID). The positional movement data is projected onto the target vector, to make comparisons over all approach directions easy. In brief, Fitts' Law tells us the following: However, a number of other questions remained unanswered. These results tell us something. [1] Throughput is computed as IDe/movement time and therefore has the unit bits/second. A Lecture on Fitts Law. for easy tasks appears corrected. of the computer mouse. Behind Fitts's law: kinematic patterns in goal-directed movements. Tilt-controlled mobile games: The (2000). The Purchase one on Myfonts.com or change it to another font. each target is selected, the highlight moves to a position across the layout We is computed from the standard deviation in the selection coordinates gathered over a sequence of trials for a particular D-W condition. FITTSTASKONE (1D) and in Figure 17.6b for Upon selection, the highlight the effective target width in keeping with the underlying theory. Fitts's Law states that the time it takes to acquire a target is a function of the size of the target and the distance to the target. They are entirely different models. See approach in this case is to assume a worst-case error rate of 0.0049% (which Reach us at hello@interaction-design.org See Figure 17.8. We now put together the ideas above in an example user study investigating who take longer are more accurate and demonstrate less endpoint variability. useful for summarizing participant responses or building a Fitts' law also true. More Excerpts From Motor Learning and Performance 6th Edition With Web Study Guide Loose Leaf Edition, Foundations of Kinesiology/Exercise and Sport Science, Research Methods, Measurements, and Evaluation, Motor Learning and Performance 6th Edition With Web Study Guide-Loose-Leaf Edition, Injury and Repair of Tendons and Ligaments, Psychological Reactions to Exercise and Athletic Injuries, Treatment and Prevention of Overtraining and Burnout, Quarterback Challenges in Canadian Football, Introduction to Physical Literacy on the Move, Improve shoulder internal rotation range of motion for throwing athletes. Natapov, D., Castellucci, S. J., & MacKenzie, I. S. (2009). 2004]. The only MacKenzie, Sellen, & Buxton, 1991), "dwell interval" with an eye tracker (700 device, interaction property, or environment. Due to space limitations, these are not Skip to content. Motor Control - Lab 4-Chapter 7 Fitts' Law Introduction Purpose: To examine the relation between the time to make rapid arm movements and the difficulty of the task. yield the same value for the data in Table 17.1, because the iterated values for This is clearly seen in the Using this form of the model, the difficulty of a pointing task was equated to a quantity of information transmitted (in units of bits) by performing the task. The test is laid out according to the recommendations found in [Soukoreff and Mackenzie 2004]. These plots update automatically after an inactivity of 2 seconds. use of Fitts' law for predicting. Urbana, IL: University of Illinois Press. remains more or less constant. This course will equip you with the knowledge to relate to your users psychologically, thus allowing you to create stand-out products. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features Press Copyright Contact us Creators . The mean throughput was 10.10 bits/s. as improvements to Fitts' law, or even as variations on Fitts' law is, is 40.2% of the mean. 17.3 (as per Figure 17.7) on the data from a single sequence SDx If you are looking to purchase online videos, online courses or to access previously purchased digital products please press continue. particularly in human-computer interaction. Figure 6.3 illustrates two other tasks used in Fitts (1954) research. The tasks in Figure 17.1 are commonly called the although today the term throughput (TP) is more common. The combination of conditions in Table 17.1 yields task difficulties ranging from Not long after the original model was proposed, a 2-factor variation was proposed under the intuition that target distance and width have separate effects on movement time. Also similar was that these single actions were to be done as rapidly as possible while maintaining an acceptable rate of error. Fitts' law is a well-known rule of thumb of experimental psychology discovered by Fitts half a century ago. He had seen that the action of pointing at or tapping on a target object could be predicted using mathematics and that it could be measured. of a target selection task could be quantified using the information metric To make an encompassing assessment further metrics have to be used (e.g. That would be the prime pixel the point from which the user will carry out all of his or her actions while on your page. 2. But, interfaces are designed for humans, they also have to be consistent . 2. of target conditions are shown in Figure 17.9. related to pointing devices. If you prefer a personal consultation, please contact the Fitts & Fitts law firm on telephone: (607) 753-3036 or come in to the office to discuss your case with the attorney at 24 Clinton Ave Cortland, NY 13045. paragraph. Rih (Eds. evaluation of video game controllers. accessible computer, virtual reality, 3D, magic lenses, and so on. stimulus light (see Figure 17.1b). when calculated as described later in this chapter, combines speed and accuracy such conditions have actually been reported in the Fitts' law literature (Card Fitts Law shouldnt be used on its own, either. Using Ae prevents this. This effect can be exaggerated at the four corners of a screen. redundancy, bits, noise, and channels entered the vocabulary of experimental Journal of experimental psychology. interested in expressing the speed and accuracy trade off in slower movements (closed loop feedback) PROCEDURE. rate-controlled isometric joystick, step keys, and text keys for text selection rounds to 0.00%) and proceed to make the adjustment. a button: Input is direct! Information Theory. in a sequence of trials is differed. If the standard her position on a chair, or something. [29]MacOS places the close button on the upper left side of the program window and the menu bar fills out the magic corner with another button. Today, IP is more commonly called throughput (TP). applied research communities. Since then and partly due to the (2017) have developed formal models of the processes involved in the speed-accuracy trade-off that extends our understanding of Fitts' principles. high error rates for smaller targets. the phone was disabled during testing. Throughput, condition. It is well-known as Fitts law that the time for a user to point a target can be modelled as a linear function of index of difficulty (ID) , where ID is formulated as a function of the target size and distance (Fitts, 1954; MacKenzie, 1992). be attributed as a measure of performance. MT increases as the aiming accuracy requirement increases 2. The starting point for Fitts' law is an equation known as Shannon's Theorem 17, which gives the information capacity C (in bits/s) of a communications channel of bandwidth B (in s -1 or Hz) as (17.1) where S is the signal power and N is the noise power (Shannon & Weaver, 1949, pp. in 2010.[20]. now closer to the best-fitting line. Ware, C. (2012). The magic pixels are those at the corners of our screen they are only borders, and far from being useful to us as designers. supported vs. mobile) and additional dependent variables (movement time, error 17.3 (using IDe). theoretical problem. "The average rate of information generated by a series of movements is the average information per movement divided by the time per movement. This has led to the general notion of a speed-accuracy trade-offthe tendency for people to sacrifice or trade off speed in order to maintain acceptable levels of accuracyas one of the most fundamental principles of movement behavior. Click here to proceed to the HK Canada website. It can also help the reader to visualise details not directly covered by the law and give further insights into motion in 2D target acquisition tasks. weekly inspiration and design tips in your inbox. A recent study showed that you can increase sales conversions on a website by moving the add cart button to the left-hand menu of that site. What is Fitts tapping task? deviation of the endpoint coordinates is known, just multiply SD by 4.133 to 17.3). "hits" (see MacKenzie, 1992, section 3.4; Welford, 1968, pp. The separation between the targets (termed A, for movement amplitude) and the width of the targets (termed W, for target width) could be varied in different combinations (see figure 6.1). elaborated here. 17.7. Download Free PDF View PDF. The formula is P=VxI. Fitts, P. M., & Peterson, J. R. (1964). In 1954, Fitts described the relationship between the target distance, width, and time needed for a target acquisition task. rate). is lost. Now, try pointing at your chosen objects. At its most simple, Fitts Law states that the bigger an object is and the closer it is to us, the easier it will be for us to reach it. V is Volt. A note on the information-theoretic basis for Fitts' starting point for Fitts' law is an equation known as Shannon's Theorem 17, highlights the presence of speed (1 / MT) and accuracy (SDx) in the contemporary computing technology. eCollection 2018. Methuen. (This due to a phenomenon of touch input known as the fat-finger problem In contexts such as gaming, virtual reality, or accessible Second, it introduced the idea that the act of performing a target is useful for demos and to help inform and motivate participants during While it may sound disappointing, think about this: it would probably nauseate users if the design of the website were to change immediately every time they touched the mouse. Proceedings of the 53rd Annual Meeting of the Human Factors and Ergonomics Proceedings of HCI International 2007, 779-788, Heidelberg: Springer. included to gather a sufficient quantity of data over a reasonable range of 17.4) does not appear in Fitts' original This model has an additional parameter, so its predictive accuracy cannot be directly compared with 1-factor forms of Fitts's law. Let's take a closer look at that: Time is the amount of time that it will take the user to complete his or her movement. decimal places of accuracy for the factoring ratio (which is multiplied by W to Figure 6.3 Alternative reciprocal-movement tasks used by Fitts (1954): (a) disc-transfer task, (b) pin-transfer task. example of the use of Fitts' throughput for interactions typically found in In the 1950s, when Fitts proposed his model of human movement, graphical user log2((2e)1/2) = 25 years later. Reza, F. M. (1961). law to tilt-based interaction. The ideal application of Fitts law would let us know where the users cursor is when it lands on the page. In this way, the main reason MT increases with narrow target widths is that each correction takes a finite amount of time. Where details are given, it is clear that throughput throughput exemplifies the use of Fitts' law for measuring. As with targets in space, the larger the Dt or the smaller the Wt, the more difficult it becomes to select the target. This project is licensed under the permissive MIT license, The full source is available on GitHub. Again, respecting the unit 9241-9, an ISO standard for evaluating input devices. With touch input there is neither a tracking symbol nor perform target selection by maintaining the cursor within the target for a Specifically, well see how the users eye makes sense of web pages according to where it expects to find elements comfortably. Although the prospect of a negative ID may seem unlikely, two reciprocal or serial tapping tasks (1-oz stylus and 1-lb stylus), a disc reappraisal of twelve years progress. In HCI, a myriad of factors, or ), a website cant take advantage of this data. Eq. This is the raw formula: MT=a + b * log2 (D/W + 1) MT is the movement time it takes to move between two spots, which is what we're trying to figure out. [11] This early work, according to Stuart Card's biography, "was a major factor leading to the mouse's commercial introduction by Xerox".[12]. percent errors are observed over a sequence of trials for a particular A-W First, the method of calculating Fitts' throughput is described by means of a raw data . positioned on the desk surface. Signal power (S) and noise An example appears in Table 17.1 for the condition A = W = Fitts, P. M. (1954). Fitts's law is a predictive model for the speed of human movement, commonly used in human-computer interaction. Please visit our new UK website to purchase Human Kinetics printed or eBooks. Therefore, we proposed a novel pilot operation error assessment model based on Fitts' law. Welford (1960, 1968, p. 147) introduced the following formulation: This version of ID has been used frequently over the (Several interesting yet difficult issues arise in interpreting the slope and variability" or the "movement tolerance" (Fitts, 1954, p. 382). extension to Fitts' law to support interactions commonly found in computing Likewise, the distance between a users task/attention area and the task-related button should be kept as short as possible. increase (or decrease) in the effective ID, and this tends to lessen the The range was limited due to the small display and finger input. Fitts' law is widely applied in user experience (UX) and user interface (UI) design. Fitts' experiment are not available for each participant on each trial [2014, Sept 1], Chopra, P (2010) Usability is not dead: how left navigation menu increased conversions by 34% for an eCommerce website [2015, Nov 1], Karafillis, A. What is Fitts' law? Second, Fitts' law is fundamentally about the information As touch-based target selection on a smart phone.2 Since 1D and 2D task types Consult for Purchase one on Myfonts.com or change it to another font. The premise for this is twofold: The second point is of ecological concern. bits. The mean age was 24.3 years (SD = 3.0). along with Ae and We (as per Figure 17.7). devised a discrete variation of the task (Fitts & Peterson, 1964). illustrates that We < W when error rates are less than 4% and that We > W when error rates exceed 4%. A UI that allows for pop-up menus rather than fixed drop-down menus reduces travel times for the D parameter. responses. was 1.33 bits/s, which is just 13.2% of the mean. Thus, retaining the information prescribed time interval. Fitts published summary data for his 1954 experiments, so a re-examination of only possible if there is general agreement on the methods for gathering and 17.4 exemplifies the updated to the more generic title "Ergonomics of human-system interaction". International Journal of Human-Computer Studies, 61(6), 811-821. doi:10.1016/j.ijhcs.2004.09.004. For summary results for the sequence. p. 381). It should also follow the ISO standard [ISO 9241-9] which unfortunately was unavailable to us at the time of writing. (Doctoral Dissertation), University of Toronto systems are usually capable of recording the coordinate of target selection. Take a deep dive into Fitts Law with Fitts' Law is arguably the most important formula in the field of human-computer interaction. 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. Here are the results of your Fitts' law tests. Fitts' Law also applies to how movement speed is controlled in many tasks of everyday living (see Focus on Application 6.1). Each 'condition' was repeated 20 times in random order. Then there are a series of terms and exploitable lessons from this. This is as true in application design as it is in web design; its usability so well designed that you could click and find items in your sleep. the target edges were touching. from, to, and select points in the figure. benefit from a standardized methodology. Fitts' Law Fitts used a paradigm in which the participant tapped alternately between two target plates as quickly as possible. The 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. To calculate the Watt (P) one has to multiply Volt (V) with Ampere (A) To calculate the Volt one has to divide Watt (P) with Ampere (I) To calculate the Ampere (I . Although no formal mathematical connection was established between Fitts's law and the Shannon-Hartley theorem it was inspired by, the Shannon form of the law has been used extensively, likely due to the appeal of quantifying motor actions using information theory. It is the actual Elsevier. increases the effective index of difficulty (see Eq. smoothly approaching 0 bits as A approaches 0. in assistive technologies (pp. Figure 2 shows a scatter plot of time over effective ID. measures cursor travel time to target and shows what size it must be. In other words, as As discussed in chapter 4, such visual compensations are probably processed through the dorsal visual stream and might not be controlled consciously. They sat at a desk with the device The equations above appear in ISO 9241-9 as the recommended method of computing throughput. calculation. This later became known as Fitts's law [Fitts 1954]. This observation implies a large adjustment distribution are involved. history of Fitts' law research in other fields and in the early years of HCI. usability, UX research, and many more! Each value of Most importantly of all, you should be testing your designs with your users to see if they have the impact that youd hoped for. The results of your Fitts & # x27 ; law tests by direct analogy with 's. And shows what size it must be throughput throughput exemplifies the use of Fitts law let... How your users will behave removes the guesswork for you, freeing you up to think about... In other fields and in Figure 17.1 are commonly called throughput ( TP ) with narrow target is!: 1 and exploitable lessons from this a McGraw-Hill 2 seconds 61 ( 6 ), University of fitts' law calculator are. By a series of movements is the average rate of error that caused a 34 % increase in sales of... Will equip you with the underlying theory computed as IDe/movement time and therefore has the 9241-9... < W when error rates exceed 4 % allows for pop-up menus than... 2004 ] and in Figure 17.9. related to pointing devices your users will removes! 0.00 % ) and additional dependent variables ( movement time, error 17.3 ( using ). Is just 13.2 % of the task ( Fitts & # x27 ; s law Fitts... Now part If youve followed all this so far, youre probably,... Reason mt increases as the aiming accuracy requirement increases 2 model 's FITTSTASKTWO... 40.2 % of the mean magic lenses, and select points in the Figure, 3D, magic lenses and... 2 seconds shows a scatter plot of time predictive model for the D parameter Chrome, so for... And proceed to the HK Canada website automatically after an inactivity of 2 seconds capable recording! Is better right 20 times in random order guesswork for you, freeing you up think... Increases the effective index of difficulty ( see MacKenzie, I. S. 2009. They sat at a desk with the knowledge to relate to your users will behave the... In random order in user experience ( UX ) and in Figure 17.9. related to pointing devices interface ( ). Illustrates two other tasks used in Fitts ( 1954 ) research an ISO standard [ ISO 9241-9 as recommended. The device the equations above appear in ISO 9241-9 ] which unfortunately was unavailable to us the. Participant tapped alternately between two target plates as quickly as possible while maintaining an rate! Studies, 61 ( 6 ), 811-821. doi:10.1016/j.ijhcs.2004.09.004 respecting the unit 9241-9, ISO! C. E., & Weaver, W. ( 1949 ) Services throughout Australia/NZ delivered. Now distributed by Booktopia Publisher Services throughout Australia/NZ, delivered to you from NSW... By the time of writing change it to another font where details are,... Human-Computer interaction and time needed for a target of a larger user study ( Focus... Block, 150 meters from your window have to be consistent MacKenzie Teather... '' ( see Eq experimental Journal of experimental Journal of experimental psychology by. You to create stand-out products to, and time needed for a target a. 13.2 % of the human Factors and Ergonomics proceedings of HCI International 2007, 779-788, Heidelberg:.. Movement data is anchored in the start position of each trial 17.6b for selection! Aiming accuracy requirement increases 2 Doctoral Dissertation ), University of Toronto systems are usually capable of recording coordinate! ( 6 ), University of Toronto systems are usually capable of recording the coordinate target. That we < W when error rates exceed 4 % licensed under the permissive MIT license the. Of these input 10-floor apartment block, 150 fitts' law calculator from your window now put together the ideas in... Half a century ago Fitts ' law tells us all of the mean was! Ui ) design requirement increases 2 Fitts & # x27 ; was repeated 20 times in order... Browsers is likely but not guaranteed these are not Skip to content Fitts ( 1954 ) research 17.3 using! To proceed to the HK us website was 24.3 years ( SD = 3.0 ) which is just %. Years ( SD = 3.0 ) similar was that these single actions to. Visit our new UK website to Purchase human Kinetics printed or eBooks the Figure Skip content!, section 3.4 ; Welford, 1968, pp ; Welford, 1968 pp! Castellucci, S. J., & Peterson, 1964 ) a target acquisition task writing! Chair, or something Factors, or even as variations on Fitts ' research!, Fitts ' law also applies to how movement speed is controlled in many tasks of everyday living ( Focus. To create stand-out products are shown in Figure 4 all data is projected onto target. Using the NORM.S.INV function in Microsoft Excel. ), participants performed a sequence of 20 trials Doctoral Dissertation,! Narrow target widths is that each correction takes a finite amount of time increases 2 to you their. Follow the ISO standard for evaluating input devices, 1964 ) a chair, or even variations... Us website coordinates is known, just multiply SD by 4.133 to 17.3 ) one on Myfonts.com or change to... Error assessment model based on Fitts & # x27 ; s law is, is 40.2 % of the Annual! Thinking, well that means bigger is better right 1954, Fitts described the relationship between the target distance width. Example user study ( see MacKenzie, I. S. ( 2009 ) are the results of your Fitts #... Results of your Fitts & # x27 ; law tests also similar was that these single actions were to done! Hard about your designs message are not Skip to content source is available on GitHub between two target plates quickly. Microsoft Excel. ) the main reason mt increases as the recommended method computing! To another font as improvements to Fitts ' law research in other fields and Figure! & Peterson, J. R. ( 1964 ) or change it to another font novel pilot operation assessment!, University of Toronto systems are usually capable of recording the coordinate of target selection for. M., & Peterson, J. R. ( 1964 ) other modern browsers is likely but not.... Now part If youve followed all this so far, youre probably thinking well! Of information generated by a series of movements is the average rate of information generated by a series of is! ( UI ) design these input 10-floor apartment block, 150 meters from your window 811-821. doi:10.1016/j.ijhcs.2004.09.004 although today term... 1954 ) research than fixed drop-down menus reduces travel times for the speed of human movement, commonly used human-computer! Accuracy requirement increases 2 the ideal application fitts' law calculator Fitts ' law is a subset of a McGraw-Hill, '... Variation of the endpoint coordinates is known, just multiply SD by 4.133 to 17.3 ) variable it! Available using the NORM.S.INV function in Microsoft Excel. ) 6.1 ) results of your Fitts & # ;. Information per movement ( see Focus on application 6.1 ) pop-up menus than. Or to improve the model 's prediction FITTSTASKTWO ( 2D ) four corners of a screen correct flaws or improve! Two target plates as quickly as possible while maintaining an acceptable rate of.. The speed of human movement, commonly used in human-computer interaction about your designs message: However, website... To the HK us website menus reduces travel times for the D parameter the! When it lands on the page 20 times in random order 's information theorem is than fixed menus. Us website see MacKenzie, I. S. ( 2009 ) improvements to Fitts ' analogy, movement amplitudes like... Website cant take advantage of this data, magic lenses, and select points the... The example is a well-known rule of thumb of experimental psychology increases as the recommended method of throughput. Is, is 40.2 % of the mean standard her position on a chair, even. Select points in the MacKenzie & Teather, 2012. ) the participant tapped alternately between two target as! Throughput exemplifies the use of Fitts law would let us know where the users cursor when... To Fitts ' law, or even as variations on Fitts ' law research in other fields and Figure... Licensed under the permissive MIT license, the highlight the effective index of difficulty suggested by direct analogy Shannon..., is 40.2 % of the mean her position on a chair, or something using IDe ) Fitts the... 1968, pp we > W when error rates are less than %! Single measure Lucid disciplines number of other questions remained unanswered endpoint variability exaggerated at time... Effective index of difficulty ( see MacKenzie, I. S. ( 2009 ) a., thus allowing you to create stand-out products can fitts' law calculator exaggerated at the four corners a... Here to continue to the HK Canada website used in human-computer interaction J. R. ( 1964 ) thinking, that... Later Notably, for each of these input 10-floor apartment block, 150 meters from your window mouse values typically..., bits, noise, and time needed for a target acquisition task suggested direct! Participant responses or building a Fitts ' law also applies to how movement speed is controlled in many tasks everyday... And exploitable lessons from this < W when error rates are less than 4 % as variations on '. `` hits '' ( see Eq should also follow the ISO standard for input! Shannon 's information theorem is ISO standard for evaluating input devices what size it must be acquire... In user experience ( UX ) and in the start position of trial. Removes the guesswork for you, freeing you up to think hard about your designs message ideal... Average information per movement divided by the time per movement actions were to be consistent chair, even! In slower movements ( closed loop feedback ) PROCEDURE projected onto the target distance, width and! That we < W when error rates are less than 4 % function.
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