Writing with a Joystick: a Comparison of Date Stamp, Selection Keyboard, and Edgewrite Jacob O

Writing with a Joystick: A Comparison of Date Stamp, Selection Keyboard, and EdgeWrite Jacob O. Wobbrock, Brad A. Myers and Htet Htet Aung Human-Computer Interaction Institute School of Computer Science Carnegie Mellon University Pittsburgh, Pennsylvania, USA {jrock, bam, hha}@cs.cmu.edu http://www.cs.cmu.edu/~edgewrite/ Abstract A joystick text entry method for game controllers and mobile phones would be valuable, since these devices often have joysticks but no conventional keyboards. But prevalent joystick text entry methods are slow because they are selection-based. EdgeWrite, a new joystick text entry method, is not based on selection but on gestures from a unistroke alphabet. Our experiment shows that this new method is faster, leaves fewer errors, and is more satisfying than date stamp and selection keyboard (two prevalent Figure 1. The Saitek P2500 Rumble Force Pad. Our experiment selection-based methods) for novices after minimal used the two thumbsticks and one of the silver buttons. practice. For more practiced users, our results show that EdgeWrite is at least 1.5 times faster than selection messenger-style text. With only selection-based text entry keyboard, and 2.4 times faster than date stamp. methods for game controllers, this can be awkward. Keywords: Text entry, text input, joystick, game controller, Mobile devices have also placed high demands on text game console, physical edges, corners, gestures, unistrokes. entry development. Numerous text entry methods have been investigated, including those driven by buttons, character 1 Introduction – Why Joystick Text Entry? recognition, virtual keyboards, thumbwheels, and voice. Joysticks have served as input devices since the earliest Many new handheld devices, such as the Ericsson T68i computers [7]. The two-player version of Computer Space , mobile phone, are equipped with miniature joysticks for the first coin-operated arcade game, used two mounted navigation and selection purposes, yet have no capability joysticks in 1972. In 1978, Atari released its first game for joystick text entry. Joystick text entry on mobile devices console, the Atari 2600, which had no keyboard, just a reduces the need for screen areas devoted to stylus entry, joystick. Joysticks have been studied in human-computer for virtual keyboards that take up precious screen real- interaction since at least the seminal study by Card et al. in estate, and for multiple button-taps to select desired 1978 [1]. Yet despite joysticks’ considerable tenure, no characters. They also can be used without looking, which satisfying text entry techniques have been developed for may have positive implications for blind use. them. The methods that do exist are mostly selection-based; Another potential use of joystick text entry is for users they require screen real-estate to display options, are of power wheelchairs. Technology is already commercially difficult to use without looking, are hard to customize, and available [22] to enable a person to control a computer’s are slow, requiring many movements per character. mouse from a power wheelchair joystick, but options for Today’s computer game industry would benefit from text entry are limited to mouse-based selection techniques, better text entry for game consoles, which often have only like the WiVik on-screen keyboard [19]. game controllers as input devices; if they have keyboards at In this paper, we present a new joystick text entry all, they are sold separately at extra cost. Many game method that is not based on selection, but on gestures. We consoles are now networked, and require extensive text use the EdgeWrite alphabet [27], originally a stylus-based entry during configuration before they allow game play. For text entry method for users with motor impairments. The example, registration for the Xbox Live! service requires properties of this alphabet make it well-suited for text entry entering personal and billing information and can take more with joysticks. Our experiment shows that joystick than 30 minutes using a joystick and an on-screen selection EdgeWrite is faster, produces more accurate phrases, and is keyboard. Furthermore, many networked games allow for more satisfying to users than date stamp or selection communication among players using short bursts of instant keyboard, two prevalent selection-based methods. 1 2 Challenges for Writing with a Joystick and at least 18% more accurate for able-bodied users Joysticks, like those found on game controllers (Figure 1), (p<.02). It was also found to be just as learnable as Graffiti commonly operate in one of two ways: position-controlled and about as fast. A detailed discussion of stylus EdgeWrite or rate-controlled. With position-control, the physical range is available elsewhere [27]. of the joystick is mapped to a plane (e.g., the screen), and the position of the stick corresponds to a position in the plane. Joystick-driven screen magnifiers have been designed using position-control [11]. With rate-control, on the other hand, the further the stick is moved from its center, the faster the position changes. Rate-control is common in first-person games and for joystick-controlled mouse cursors [13]. It would seem that position-control might be the ideal candidate for “writing” with a joystick, as a user could trace an ( x, y) path like she does with a stylus on a PDA. Many studies, however, confirm that joysticks are not as accurate for positioning as mice, trackballs, touchpads, and tablets Figure 2. The EdgeWrite alphabet. Alternate forms exist for most (e.g., [1, 5, 15, 18]). Indeed, our design explorations characters (not shown). The bowing of line segments is only confirm the difficulty of making smooth letter-forms using illustrative and does not depict actual movement, which is in a joystick. The prospect of writing in an alphabet like straight lines. For more detail, see [27]. Graffiti is therefore dubious. If gestures are to be used, they will have to be designed to overcome this difficulty. 3.1 The EdgeWrite Alphabet Human physiology also complicates joystick text entry. The EdgeWrite alphabet has properties that make it well- For example, the dexterity of the thumb changes with its suited to meeting the challenges of joystick text entry. The position relative to the hand, causing changes in range of alphabet is unique among unistroke methods in that every motion [8]. The index finger has the highest Fitts’ index of character is comprised of up to six well-defined segments performance [12], making it better suited than the thumb for between the vertices of a square (i.e., the four sides and the control tasks [4]. The velocity of a writer depends on two diagonals). Thus, all motion in EdgeWrite is ideally in whether she moves her arm or only her wrist, and upward straight lines between corners. But straight lines are not strokes are generally faster than downward ones [9]. Some required for gesture recognition, since recognition depends results show that humans have a difficult time returning a not on the path of movement but instead on the sequence of joystick to the same position it was before [11]. Other corners that are hit. results show humans often under- or overshoot their targets EdgeWrite can be easily implemented on any surface while using joysticks, and that joystick movement can be that has a square area bounded by physical edges. Physical tremulous, comprised of sub-movements and repeated in- edges provide a Fitts’ Law benefit, as they allow for “target path corrections [17]. Such variables may subvert any overshoot” without sacrificing accuracy [26]. Physical attempts at “writing” with joysticks. edges also provide tangible feedback during movement and While not a panacea, EdgeWrite is well-suited to result in greater speed and stability of motion [25]. overcoming many of these challenges. The next section Joysticks are usually best used for control, not explains why. positioning. But EdgeWrite’s use of stabilizing physical edges allows joysticks bounded by square areas to be used 3 A New Method Based on EdgeWrite in position-control mode for writing EdgeWrite characters. The EdgeWrite text entry method was invented to help The areas bounding the thumbsticks on the Saitek P2500 people with motor impairments enter text with a stylus on a (Figure 1) are squares with slightly rounded corners. In our PDA. Many people with motor impairments have difficulty study, we used this joystick without modification. writing Graffiti because of their inability to make smooth With a joystick it is difficult to make smooth characters, curves and straight lines due to tremor or rapid fatigue [25]. such as those required by Graffiti, but EdgeWrite characters The stylus version of EdgeWrite addressed these problems are easy to make by pushing the stick from corner to corner by offering a more accurate and physically stable means of within the plastic bounding area. Edges naturally guide the text entry through the use of physical edges [26]. In fact, all stick, and corners naturally pocket it, making accurate stylus entry in EdgeWrite is performed within the confines motions easy. As shown in Figure 2, EdgeWrite characters of a small plastic square, and all strokes are along the edges begin in one of four corners, easily accessed from the center or diagonals and into the corners of this square. Recognition of a square with a self-centering joystick. works not by analyzing the path of movement, but by Isokoski [9] offers a complexity measure designed to examining the order in which the corners of the square are compare unistroke alphabets by abstracting their characters hit. When compared to Graffiti, EdgeWrite was hugely into composites of straight lines. EdgeWrite requires no more accurate for some people with motor impairments, such abstraction, as its characters are already comprised of 2 straight lines. The complexity of the EdgeWrite letters in This difficulty arises because the thumb’s dexterity and Figure 2 is 2.30, lower, and thus “faster,” than Roman range of motion along one diagonal is much better than letters (2.76), Graffiti (2.54), and MDITIM (3.06), but along the other diagonal.

Load more