Three experiments compared wrist and arm performance in a cyclical Fitts’ target task. The purpose of Experiment I was to determine if movement kinematics differed for wrist/elbow flexion/extension movements to targets of varying difficulty. Participants were asked to flex/extend a manipulandum in the horizontal plane at the wrist and elbow joint in an attempt to move back and forth between two targets. Online knowledge of effector position was displayed as a visual trace on a projector screen. Target widths were manipulated with amplitude constant (16 degrees) in order to create Indexes of Difficulty of 1.5, 3, 4.5, and 6. Results failed to detect differences in elbow and wrist movements either in terms of movement time, movement accuracy, or kinematic characteristics of the movement. In studies that have reported difference in wrist and arm performance in Fitts’ target tasks, experimenters have typically utilized visual amplification to counterbalance the small resulting wrist movements. The purpose of Experiments II and III was to investigate how changes in task parameters and visual gain play a role in providing a performance advantage for the wrist. In these experiments arm movement amplitude was increased to 32 degrees and wrist amplitude was decreased to 8 degrees. Results found similar overall movement times for arm and wrist movements. However, kinematic analysis of the movement revealed relatively large dwell times for wrist movements at IDs of 4.5 and 6. Removal of dwell time resulted in faster movement times for the wrist compared to arm. The results of these three experiments add to the limited literature examining how different effectors perform a Fitts’ target task. These findings suggest that performance differences in past literature may be due to the visual amplification often used when arm, wrist, and finger movements are studied.

Past research has indicated that motor imagery, or imagined movement, follows Fitts' law similarly to physical movement. Additionally, motor imagery has been shown to improve real motor performance in multiple contexts, showcasing a remarkable connection with real motion. The current study examines how the subject of motor imagery, imagining oneself, another person, or an object, impacts this faithfulness to real movement, specifically in following Fitts' law. Participants viewed 2D photos of a virtual environment with an "X", a humanoid, or a disc facing a gate at 6 distances and 4 widths for 24 combinations. Each combination was repeated twice randomly for 48 trials per condition, and conditions were presented in random order for a total of 144 trials. Results indicate that object-imagery does trigger motor imagery and follow Fitts' law, in contrast to prior research. However, further analysis showed that the function produced in the object condition was significantly different from both self and other, while self and other were not significantly different from one another. This was due to a higher index of performance value in the object condition, implying that participants assigned the object different abilities than the two human-centered conditions. These results indicate a difference related to biological, or perhaps human, motion, and future studies should further explore the impact of the subject and characteristics of the subject on motor imagery. Understanding these intricacies is crucial to refine and understand the benefits of motor imagery seen in multiple motor performance contexts.

Touchscreen technology is gradually becoming more popular and massive in our present society to the point where it is hard to find a person that has never used this interface system. Handheld devices such as mobile phones and tablets are predominantly based on touchscreens as the main way to interact with them. Nevertheless, that is not the case when it comes to personal computers either desktop machines or laptops which are still chiefly based on traditional keyboard and mouse as their main input system. In this study we explore the potential that touchscreen based interface can offer for personal computers carrying through an observational experiment with six participants that were asked to perform a list of tasks using both traditional keyboard-mouse interface and touchscreen interface. The measurements during the observation concerned time and error rate for every task. Each participant was interviewed right after the completion of the observational phase in order to get a qualitative insight on their views and perceptions regarding both interfaces. The data collected was analyzed based on some existing models within touchscreen interface and human-computer interaction that have been elaborated in previews research. The final results led to the conclusion, that touchscreen-based interface proved to be slower and have higher error rate than traditional interface in a big number of the tasks performed by the participants. Similarly, the general perception of the people towards having touchscreen on a personal computer still seems a bit doubtful, although they do see some concrete positive aspects about this interface. Nevertheless, touchscreen outperformed traditional interface in some particular tasks. This implies that touchscreen interface has a clear potential for personal computers that would let users utilize these machines in a much broader and more interactive way than people do it today with the traditional keyboard-mouse interface.

Recent, innovative developments in the field of gesture interfaces as input techniques have the potential to provide a basic, lower-cost, point-and-click function for graphic user interfaces (GUIs). Since these gesture interfaces are not yet widely used, indeed no tilt-based gesture interface is currently on the market, there is neither an international standard for the testing procedure nor a guideline for their ergonomic design and development. Hence, the research area demands more design case studies on a practical basis. The purpose of the research is to investigate the design factors of gesture interfaces for the point-andclick task in the desktop computer environment. The key function of gesture interfaces is to transfer the specific body movement into the cursor movement on the two-dimensional graphical user interface(2D GUI) on a real-time basis, based in particular on the arm movement. The initial literature review identified limitations related to the cursor movement behaviour with gesture interfaces. Since the cursor movement is the machine output of the gesture interfaces that need to be designed, a new accuracy measure based on the calculation of the cursor movement distance and an associated model was then proposed in order to validate the continuous cursor movement. Furthermore, a design guideline with detailed design requirements and specifications for the tilt-based gesture interfaces was suggested. In order to collect the human performance data and the cursor movement distance, a graphical measurement platform was designed and validated with the ordinary mouse. Since there are typically two types of gesture interface, i.e. the sweep-based and the tilt-based, and no commercial tilt-based gesture interface has yet been developed, a commercial sweep-based gesture interface, namely the P5 Glove, was studied and the causes and effects of the discrete cursor movement on the usability was investigated. According to the proposed design guideline, two versions of the tilt-based gesture 3 interface were designed and validated based on an iterative design process. Most of the phenomena and results from the trials undertaken, which are inter-related, were analyzed and discussed. The research has contributed new knowledge through design improvement of tilt-based gesture interfaces and the improvement of the discrete cursor movement by elimination of the manual error compensation. This research reveals that there is a relation between the cursor movement behaviour and the adjusted R 2 for the prediction of the movement time across models expanded from Fitts’ Law. In such a situation, the actual working area and the joint ranges are lengthy and appreciably different from those that had been planned. Further studies are suggested. The research was associated with the University Alliance Scheme technically supported by Freescale Semiconductor Co., U.S.

Swiftpoint is a promising new computer pointing device that is designed primarily for mobile computer users in constrained space. Swiftpoint has many advantages over current pointing devices: it is small, ergonomic, has a digital ink mode, and can be used over a flat keyboard. This thesis aids the development of Swiftpoint by formally evaluating it against two of the most common pointing devices with today's mobile computers: the touchpad, and mouse. Two laws commonly used with pointing devices evaluations, Fitts' Law and the Steering Law, were used to evaluate Swiftpoint. Results showed that Swiftpoint was faster and more accurate than the touchpad. The performance of the mouse was however, superior to both the touchpad and Swiftpoint. Experimental results were reflected in participants' choice for the mouse as their preferred pointing device. However, some participants indicated that their choice was based on their familiarity with the mouse. None of the participants chose the touchpad as their preferred device.

abstract: ABSTRACT The present studies investigated the separate effects of two types of visual feedback delay – increased latency and decreased updating rate – on performance – both actual (e.g. response time) and subjective (i.e. rating of perceived input device performance) – in 2-dimensional pointing tasks using a mouse as an input device. The first sub-study examined the effects of increased latency on performance using two separate experiments. In the first experiment the effects of constant latency on performance were tested, wherein participants completed blocks of trials with a constant level of latency. Additionally, after each block, participants rated their subjective experience of the input device performance at each level of latency. The second experiment examined the effects of variable latency on performance, where latency was randomized within blocks of trials. The second sub-study investigated the effects of decreased updating rates on performance in the same manner as the first study, wherein experiment one tested the effect of constant updating rate on performance as well as subjective rating, and experiment two tested the effect of variable updating rate on performance. The findings suggest that latency is negative correlated with actual performance as well as subjective ratings of performance, and updating rate is positively correlated with actual performance as well as subjective ratings of performance. / Dissertation/Thesis / Masters Thesis Applied Psychology 2015

Du fait de la disponibilité de capteurs éléctroniques de plus en plus puissant, la dernière décennie a vu la popularisation de nouveaux dispositifs mobiles, comme les téléphones intelligents (smartphone), et même des dispositifs miniatures comme ceux de l'informatique portée. Ces nouveaux dispositifs apportent de nouveaux problèmes interactionnels, du fait de la petite taille de l'écran et du problème du "fat-finger" (lors de l'interaction, une large portion de l'écran se retrouve occultée par le doigt, et les tâches de pointage perdent en précision. L'objectif de ce travail est double : 1) d'acquérir une meilleure compréhension du pointage sur les petits dispositifs mobiles, grâce à une étude poussée de la loi Fitts, 2) de créer de nouvelles techniques d'interaction afin d'augmenter la bande passante interactionnelle entre l'utilisateur et le dispositif / Thanks to the availability of powerful miniaturized electronic coponents, this last decade have seen the popularization of small mobile devices such as smartphones, and even smaller devices for wearable computing. These new devices bring new interaction problems, such as the small size of the screen and the "fat-finger" problem (a relatively large portion of the sreen is occluded and pointing lacks precision). the objective of the work reported here is twofold : 1) to aquire a better understanding of pointing on small devices, thanks to an advanced study of Fitts' law, 2) to design new interaction techniques for increasing the interaction bandwidth between the user and the device.

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Distal pointing is the interaction style defined by directly pointing at targets from a distance. It follows a laser pointer metaphor and the position of the cursor is determined by the intersection of a vector extending the pointing device with the display surface. Distal pointing as a basic interaction style poses several challenges for the user, mainly because of the lack of precision humans have when using it. The focus of this thesis is to understand and improve distal pointing, making it a viable interaction metaphor to be used in a wide variety of applications. We achieve this by proposing and validating a predictive model of distal pointing that is inspired by Fitts' law, but which contains some unique features. The difficulty of a distal pointing task is best described by the angular size of the target and the angular distance that the cursor needs to go across to reach the target from the input device perspective. The practical impact of this is that the user's relative position to the target should be taken into account. Based on the model we derived, we proposed a set of design guidelines for high-precision distal pointing techniques. The main guideline from the model is that increasing the target size is much more important than reducing the distance to the target. In order to improve distal pointing, we followed the model guidelines and designed interaction techniques that aim at improving the precision of distal pointing tasks. Absolute and Relative Mapping (ARM) distal pointing increases precision by offering the user a toggle which changes the control/display (CD) ratio such that a large movement of the input device is mapped to a small movement of the cursor. Dynamic Control Display Ratio (DyCoDiR) automatically increases distal pointing precision, as the user needs it. DyCoDiR takes into account the user distance to the interaction area and the speed at which the user moves the input device to dynamically calculate an increased CD ratio, making the action more precise the steadier the user tries to be. We performed an evaluation of ARM and DyCoDiR comparing them to basic distal pointing in a realistic context. In this experiment, we also provided variations of the techniques which increased the visual perception of targets through zooming in the area around the cursor when precision was needed. Results from the study show that ARM and DyCoDiR are significantly faster and more accurate than basic distal pointing with tasks that require very high precision. We analyzed user navigation strategies and found that the high precision techniques afford users to remain stationary while performing interactions. However, we also found that individual differences have a strong impact on the decision to walk or not, and that, sometimes, is more important than the technique affordance. We provided a validation for the distal pointing model through the analysis of expected difficulty of distal pointing tasks in light of each technique tested. We propose selection by progressive refinement, a new design concept for distal pointing selection techniques, whose goal is to offer the ability to achieve near perfect accuracy in selection at very cluttered environments. The idea of selection by progressive refinement is to gradually eliminate possible targets from the set of selectable objects until only one object is available for selection. We implemented SQUAD, a selection by progressive refinement distal pointing technique, and performed a controlled experiment comparing it to basic distal pointing. We found that there is a clear tradeoff between immediate selections that require high precision and selections by progressive refinement which always require low precision. We validated the model by fitting the distal pointing data and proposed a new model, which has a linear growth in time, for SQUAD selection. / Ph. D.