65,749 research outputs found
Using Variable Dwell Time to Accelerate Gaze-Based Web Browsing with Two-Step Selection
In order to avoid the "Midas Touch" problem, gaze-based interfaces for
selection often introduce a dwell time: a fixed amount of time the user must
fixate upon an object before it is selected. Past interfaces have used a
uniform dwell time across all objects. Here, we propose a gaze-based browser
using a two-step selection policy with variable dwell time. In the first step,
a command, e.g. "back" or "select", is chosen from a menu using a dwell time
that is constant across the different commands. In the second step, if the
"select" command is chosen, the user selects a hyperlink using a dwell time
that varies between different hyperlinks. We assign shorter dwell times to more
likely hyperlinks and longer dwell times to less likely hyperlinks. In order to
infer the likelihood each hyperlink will be selected, we have developed a
probabilistic model of natural gaze behavior while surfing the web. We have
evaluated a number of heuristic and probabilistic methods for varying the dwell
times using both simulation and experiment. Our results demonstrate that
varying dwell time improves the user experience in comparison with fixed dwell
time, resulting in fewer errors and increased speed. While all of the methods
for varying dwell time resulted in improved performance, the probabilistic
models yielded much greater gains than the simple heuristics. The best
performing model reduces error rate by 50% compared to 100ms uniform dwell time
while maintaining a similar response time. It reduces response time by 60%
compared to 300ms uniform dwell time while maintaining a similar error rate.Comment: This is an Accepted Manuscript of an article published by Taylor &
Francis in the International Journal of Human-Computer Interaction on 30
March, 2018, available online:
http://www.tandfonline.com/10.1080/10447318.2018.1452351 . For an eprint of
the final published article, please access:
https://www.tandfonline.com/eprint/T9d4cNwwRUqXPPiZYm8Z/ful
The Role of Text Pre-processing in Sentiment Analysis
It is challenging to understand the latest trends and summarise the state or general opinions about products due to the big diversity and size of social media data, and this creates the need of automated and real time opinion extraction and mining. Mining online opinion is a form of sentiment analysis that is treated as a difficult text classification task. In this paper, we explore the role of text pre-processing in sentiment analysis, and report on experimental results that demonstrate that with appropriate feature selection and representation, sentiment analysis accuracies using support vector machines (SVM) in this area may be significantly improved. The level of accuracy achieved is shown to be comparable to the ones achieved in topic categorisation although sentiment analysis is considered to be a much harder problem in the literature
Whether and Where to Code in the Wireless Relay Channel
The throughput benefits of random linear network codes have been studied
extensively for wirelined and wireless erasure networks. It is often assumed
that all nodes within a network perform coding operations. In
energy-constrained systems, however, coding subgraphs should be chosen to
control the number of coding nodes while maintaining throughput. In this paper,
we explore the strategic use of network coding in the wireless packet erasure
relay channel according to both throughput and energy metrics. In the relay
channel, a single source communicates to a single sink through the aid of a
half-duplex relay. The fluid flow model is used to describe the case where both
the source and the relay are coding, and Markov chain models are proposed to
describe packet evolution if only the source or only the relay is coding. In
addition to transmission energy, we take into account coding and reception
energies. We show that coding at the relay alone while operating in a rateless
fashion is neither throughput nor energy efficient. Given a set of system
parameters, our analysis determines the optimal amount of time the relay should
participate in the transmission, and where coding should be performed.Comment: 11 pages, 12 figures, to be published in the IEEE JSAC Special Issue
on Theories and Methods for Advanced Wireless Relay
The Interplay between attention, experience and skills in online language teaching
The demand for online teaching is growing as is the recognition that online teachers require highly sophisticated skills to manage classrooms and create an environment conducive to learning. However, there is little rigorous empirical research investigating teachers’ thoughts and actions during online tutorials. Taking a sociocultural perspective, this study explores the interplay between the attention focus of language teachers during synchronous online tutorials and their reflections on their own teaching practices. Eyetracking data show that patterns of attention focus on different areas of the screen (representing technical facilities, social interaction and content) are related to practitioners’ experience in online teaching including familiarity with a particular platform. In particular, those with less online teaching experience display greater attention to technical areas than their more experienced colleagues.
These findings are confirmed in the teachers’ reflective interviews, stimulated by watching gazeplot videos of their online tutorials. Their reflections also yield deeper insight into reasons for particular actions. Thematic analysis was used to relate the reflections on teaching strategies to the levels of online teaching skills (Hampel & Stickler 2005, New skills for new classrooms: Training tutors to teach languages online. Computer Assisted Language Learning 18(4). 311–326). Our research has extended Bax’s normalisation (2003, CALL – past, present and future. System 31(1). 13–28. doi: 10.1016/s0346-251x(02)00071-4) of the use of technology in face-to-face classroom learning into online learning environments. Mirroring the ontogenetic development of increasing digitalisation, teachers in online environments appropriate the skills necessary to free cognitive resources for attending to social and pedagogic aspects of their teaching
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