Nomadic input on mobile devices: the influence of touch input technique and walking speed on performance and offset modeling

In everyday life people use their mobile phones on-the-go with different walking speeds and with different touch input techniques. Unfortunately, much of the published research in mobile interaction does not quantify the influence of these variables. In this paper, we analyze the influence of walking speed, gait pattern and input techniques on commonly used performance parameters like error rate, accuracy and tapping speed, and we compare the results to the static condition. We examine the influence of these factors on the machine learned offset model used to correct user input and we make design recommendations. The results show that all performance parameters degraded when the subject started to move, for all input techniques. Index finger pointing techniques demonstrated overall better performance compared to thumb-pointing techniques. The influence of gait phase on tap event likelihood and accuracy was demonstrated for all input techniques and all walking speeds. Finally, it was shown that the offset model built on static data did not perform as well as models inferred from dynamic data, which indicates the speed-specific nature of the models. Also, models identified using specific input techniques did not perform well when tested in other conditions, demonstrating the limited validity of offset models to a particular input technique. The model was therefore calibrated using data recorded with the appropriate input technique, at 75% of preferred walking speed, which is the speed to which users spontaneously slow down when they use a mobile device and which presents a tradeoff between accuracy and usability. This led to an increase in accuracy compared to models built on static data. The error rate was reduced between 0.05% and 5.3% for landscape-based methods and between 5.3% and 11.9% for portrait-based methods

Effects of feedback, mobility and index of difficulty on deictic spatial audio target acquisition in the horizontal plane

We present the results of an empirical study investigating the effect of feedback, mobility and index of difficulty on a deictic spatial audio target acquisition task in the horizontal plane in front of a user. With audio feedback, spatial audio display elements are found to enable usable deictic interac-tion that can be described using Fitts law. Feedback does not affect perceived workload or preferred walking speed compared to interaction without feedback. Mobility is found to degrade interaction speed and accuracy by 20%. Participants were able to perform deictic spatial audio target acquisition when mobile while walking at 73% of their pre-ferred walking speed. The proposed feedback design is ex-amined in detail and the effects of variable target widths are quantified. Deictic interaction with a spatial audio display is found to be a feasible solution for future interface designs

Controlled Experimentation in Naturalistic Mobile Settings

Performing controlled user experiments on small devices in naturalistic mobile settings has always proved to be a difficult undertaking for many Human Factors researchers. Difficulties exist, not least, because mimicking natural small device usage suffers from a lack of unobtrusive data to guide experimental design, and then validate that the experiment is proceeding naturally.Here we use observational data to derive a set of protocols and a simple checklist of validations which can be built into the design of any controlled experiment focused on the user interface of a small device. These, have been used within a series of experimental designs to measure the utility and application of experimental software. The key-point is the validation checks -- based on the observed behaviour of 400 mobile users -- to ratify that a controlled experiment is being perceived as natural by the user. While the design of the experimental route which the user follows is a major factor in the experimental setup, without check validations based on unobtrusive observed data there can be no certainty that an experiment designed to be natural is actually progressing as the design implies.Comment: 12 pages, 3 table

A PSYCHOLINGUISTIC ANALYSIS OF DYSLEXIA IN BACKWARDS: THE RIDDLE OF DYSLEXIA

This study is under a psycholinguistic umbrella. The aim of this study is to analyze linguistic phenomena of dyslexia suffered by Brian, the main character in Backwards: The Riddle of Dyslexia. This study has three objectives: (1) to identify and explain the types of linguistic errors experienced by the main character in Backwards: The Riddle of Dyslexia; (2) to examine the environmental factors which occur in the movie; and (3) to describe the kinds of teaching approaches used to recover the main character in the movie from dyslexia. This study employed a descriptive qualitative method since it emphasized on describing the phenomena of dyslexia in Backwards: The Riddle of Dyslexia. Moreover, the findings were presented in narrative or textual description. However, number was also used to support the analysis of the data. Some steps in analyzing the data were: identifying the raw data, classifying each datum into the categorization, analyzing each datum, interpreting each datum based on its contexts, reporting the findings, and drawing the conclusion. Finally, the data findings were triangulated by two linguistics students who were keen on psycholinguistics. This study reveals three findings. First, of eight types of miscues, only six types occur in Backwards: The Riddle of Dyslexia. They are substitution, hesitation, omission, non-response, addition, and self-corrections. Meanwhile, the absent types are repetition and reversal. Substitution is the most common error made by a dyslexic who has problems in extracting printed letters into sounds. Meanwhile, the other types have only small occurrences since they are not common errors made by a dyslexic. Second, all types of environmental factors occur in the movie, i.e. social interaction and communication, physical environment, cognitive modality preference, emotional motivation, and children’s behavior. Social interaction and communication as well as physical environment become the highest in rank because Brian works well with another and needs a suitable condition and situation to read. Finally, each type of environmental factors supports successful teaching approaches for a dyslexic. Third, types of teaching approaches which occur in the movie are language experience, teacher modeling, self-questioning, phonological approach, and engaging parents. Meanwhile, the absent types are creative writing and critical literacy. Those present types of teaching approaches have represented successful treatments for Brian to recover from dyslexia. Key words: psycholinguistics, dyslexia, Backwards: The Riddle of Dyslexi

Non-local first-order modelling of crowd dynamics: a multidimensional framework with applications

In this work a physical modelling framework is presented, describing the intelligent, non-local, and anisotropic behaviour of pedestrians. Its phenomenological basics and constitutive elements are detailed, and a qualitative analysis is provided. Within this common framework, two first-order mathematical models, along with related numerical solution techniques, are derived. The models are oriented to specific real world applications: a one-dimensional model of crowd-structure interaction in footbridges and a two-dimensional model of pedestrian flow in an underground station with several obstacles and exits. The noticeable heterogeneity of the applications demonstrates the significance of the physical framework and its versatility in addressing different engineering problems. The results of the simulations point out the key role played by the physiological and psychological features of human perception on the overall crowd dynamics.Comment: 26 pages, 17 figure

An inverse dynamics model for the analysis, reconstruction and prediction of bipedal walking

Walking is a constrained movement which may best be observed during the double stance phase when both feet contact the floor. When analyzing a measured movement with an inverse dynamics model, a violation of these constrains will always occur due to measuring errors and deviations of the segments model from reality, leading to inconsistent results. Consistency is obtained by implementing the constraints into the model. This makes it possible to combine the inverse dynamics model with optimization techniques in order to predict walking patterns or to reconstruct non-measured rotations when only a part of the three-dimensional joint rotations is measured. In this paper the outlines of the extended inverse dynamics method are presented, the constraints which define walking are defined and the optimization procedure is described. The model is applied to analyze a normal walking pattern of which only the hip, knee and ankle flexions/extensions are measured. This input movement is reconstructed to a kinematically and dynamically consistent three-dimensional movement, and the joint forces (including the ground reaction forces) and joint moments of force, needed to bring about this movement are estimated

Pedestrian flows in bounded domains with obstacles

In this paper we systematically apply the mathematical structures by time-evolving measures developed in a previous work to the macroscopic modeling of pedestrian flows. We propose a discrete-time Eulerian model, in which the space occupancy by pedestrians is described via a sequence of Radon positive measures generated by a push-forward recursive relation. We assume that two fundamental aspects of pedestrian behavior rule the dynamics of the system: On the one hand, the will to reach specific targets, which determines the main direction of motion of the walkers; on the other hand, the tendency to avoid crowding, which introduces interactions among the individuals. The resulting model is able to reproduce several experimental evidences of pedestrian flows pointed out in the specialized literature, being at the same time much easier to handle, from both the analytical and the numerical point of view, than other models relying on nonlinear hyperbolic conservation laws. This makes it suitable to address two-dimensional applications of practical interest, chiefly the motion of pedestrians in complex domains scattered with obstacles.Comment: 25 pages, 9 figure