The effect of keypad angle of a table keyphone on keying performance

Two keypad angle experiments, one numeral legibility experiment and one button-tapping rate experiment are described. The effects of keypad angle on keyphone positioning, keying time, keying errors and on a keying performance measure are discussed. A geometrical method for estimating optimum keypad angle is introduced.

It is concluded that the optimum angle for a keypad depends on its height above the desk surface. The geometrical method can be used to estimate the best anglein the absence of experimental evidence. For the experimental keyphone (keypad height about 90 mm) the best keypad angle was found to be about 25° to the horizontal, but the effect of a 10° deviation either way from this angle was quite small.     

An Extended Comparison of Telephone Keying and Dialling Performance

Abstract

The results of a 2y extended experiment on keying and dialling are presented. The experiment was designed to investigate the relative error rates on push-button telephones (keyphones) and dial telephones, and the variation in the error rates as users became more experienced.

Seventy office workers, who were due to have 12-button keyphones installed, and a control group of 20 dial telephone users took part. Their performance was assessed on 11 occasions during the 2 y period, ft was found that the time taken to key numbers (all seven digits long) did not vary significantly between tests. The keying error rate exceeded the dialling error rate throughout the experiment. The keying error rate was related to the amount of keying experience, decreasing during the first 20 weeks of the study and then levelling off. An exponential curve was found to be a good fit to the keying error data. The dialling error rate did not vary significantly during the experiment. The distribution of different types of error and the number of self-detected errors did not vary with experience. Subjects aged fifty years or older made more errors than younger subjects.

It is concluded that, even when performance has stabilised after the learning period, keying errors occur more frequently than dialling errors. The impact of this increase in error rate may be reduced by the introduction of new keyphone designs and an increase in the use of repertory diallers.     

Are there task specific performance effects for differently configured numeric keypads?

Previous studies of numeric keypad user preference and performance have indicated that the telephone layout (TEL) was superior to the layout seen on computer keyboards and adding machines (ADD). A recent study (Straub and Granaas, 1993) suggested that the TEL preference was subject to task specific effects. To investigate the possibility of task specific performance in using keypads, 24 subjects were tested on four different keypad layouts (TEL, zero at top; TEL, zero at bottom; ADD, zero at top; ADD, zero at bottom) using three different tasks (four digit strings, seven digit strings, and seven digit strings depicted like standard North American telephone numbers). Results indicated that differences in rate of performance across the four keypad layouts were the result of zero placement, with the zero in the bottom position yielding the fastest keypad use. No significant differences were found for error rate across the different keypads. No task specific performance effects were found. These findings suggest that either the ADD or TEL layouts could be adopted universally for numeric keypads, with the stipulation that the zero key be placed below the other keys.     

Speech feedback for touch-keying

A person keying an unfamiliar number listed in a directory, a driver keying, a mobile telephone, and a blind person making a call all face a common problem: how to key a telephone number without looking at the phone. We studied whether touch-keying that is, keying without looking would be facilitated by a talking keyset which spoke the names of the keys as they were pressed. To establish a baseline level of touch-keying performance, we also studied touch-keying with the standard TOUCH-TONE“ feedback. We found that touch-keying was much more accurate with speech than with tone feedback. Speed was not sacrificed to achieve higher accuracy; on the contrary, touch-keying was slightly but consistently faster with speech than with tone feedback. Speech feedback enabled users to catch and correct, via a CLEAR key, over 80% of their errors; tone feedback was much less effective in this regard. No training or practice was necessary to reap the benefits of speech feedback; moreover, the benefits persisted even after extensive practice. The pattern of errors suggests strongly that mistakes in touch-keying were due to misaiming and hitting the wrong key. Misaiming errors were especially common between keys in the 456 and 789 rows, and between the 8 and 0 keys on the telephone keyset.     

Reactions,accuracy and response complexity of numerical typing on touch screens

Touch screens are popular nowadays as seen on public kiosks, industrial control panels and personal mobile devices. Numerical typing is one frequent task performed on touch screens, but this task on touch screen is subject to human errors and slow responses. This study aims to find innate differences of touch screens from standard physical keypads in the context of numerical typing by eliminating confounding issues. Effects of precise visual feedback and urgency of numerical typing were also investigated. The results showed that touch screens were as accurate as physical keyboards, but reactions were indeed executed slowly on touch screens as signified by both pre-motor reaction time and reaction time. Provision of precise visual feedback caused more errors, and the interaction between devices and urgency was not found on reaction time. To improve usability of touch screens, designers should focus more on reducing response complexity and be cautious about the use of visual feedback.

Practitioner Summary: The study revealed that slower responses on touch screens involved more complex human cognition to formulate motor responses. Attention should be given to designing precise visual feedback appropriately so that distractions or visual resource competitions can be avoided to improve human performance on touch screens.     

Performance effects of reduced proprioceptive feedback on touch typists and casual users in a typing task

This study examined performance and acceptance effects of lack of kinesthetic and tactile feedback from the keyboard in a typing task with two subject groups of differing skill level: touch typists and casual users. Subjects' objective performance (e.g., speed, accuracy, throughput) and subjective acceptance (questionnaire) was evaluated for both a conventional full travel keyboard and a prototype piezoelectric flat keyboard which lacked familiar kinesthetic and tactile feedback. Any performance decrement present with the flat keyboard was expected to diminish with practice for the touch typists due to transfer and adaptation of typing skills. Performance for both subject groups was significantly higher with the conventional keyboard and touch typists' performance was more adversely affected by the flat keyboard than casual users'. No performance improvement with practice was found for one subject group relative to the other or for one keyboard relative to the other. It was concluded the touch typists were unable to adapt to the unusual feedback conditions present with the piezo-electric fiat keyboard.     

Ergonomic aspects of aircraft keyboard design: the effects of gloves and sensory feedback on keying performance

Increasing requirements for aircraft keyboards have indicated inadequacies in ergonomic standards for airborne environments, in particular for tasks involving unskilled, discontinuous data entry, with emphasis on accuracy rather than speed. Four experiments are reported from a programme of research aimed at the development and application of methodologies for assessing factors relevant to keyboard design. Experiment 1 demonstrated that the effects of various aircrew gloves on a representative aircraft data entry task are highly situation specific. Experiment 2 showed that gloves impaired performance on a high compatibility continuous keying task, with relatively high keying rates, and that this impairment was not reduced by additional auditory feedback. Experiment 3 demonstrated that the high compatibility keying task provided a successful methodology for investigating the effects of key displacement and resistance on speed and accuracy. Experiment 4 indicated the relative contributions of reduced tactility and mobility to the effects on keying and manipulative performance caused by aircrew gloves. Together, these experiments suggest that kinaesthetic and tactile feedback associated with keying are relatively unaffected by aircrew gloves, and that restrictions on mobility caused by gloves may be more important for continuous data entry involving relatively high keying rates     

Task-specific preference for numeric keypads

The present study examined task-specific user preferences for two numeric keypads. Eight scenarios describing numerical entry tasks were presented to 100 subjects. For each scenario, subjects were to choose the keypad of their choice between the ADD(ing machine) and TEL(ephone) arrangements. Scenarios including entering telephone numbers, the subject's personal identification number, other identification numbers, single digits, and mathematical calculations. A repeated-measures ANOVA showed a significant main effect for scenario on preference. When scenarios described telephone number entry tasks, preference for TEL was as high as 82%, whereas preference for TEL was as low as 50% when the scenario described mathematical calculations. It is suggested that task-specific preferences may be valuable design considerations, and could correspond to task-specific performance differences.     

基于模糊控制的半数字键盘电梯群控系统

电梯群控系统的结构决定着电梯交通信息的完善性。信息的非完整性妨碍了电梯群控调度算法的实施。而全数字键盘虽然可以对电梯实施更好的调度,但是硬件的安装增加了电梯系统的成本。文中介绍了一种经济型的半数字键盘的电梯群控模型,能够降低成本和获取必要的客流信息。基于乘客两种不同需求的考虑,推导了乘客的最长候梯时间和最大冲击数的估算公式,采用基于模糊控制的电梯群控策略,符合人们对电梯服务水平的语言级评价。文中仿真试验在采用的半数字电梯群控系统和常规电梯群控系统、全数字群控系统之间做了比较。结果表明,该群控模型表现出较好的性能,乘客的乘梯时间和服务时间有所降低,是一种经济实用的群控模型。     

Enhanced auditory feedback for Korean touch screen keyboards

With the increasing popularity of touch screen mobile devices, improving the usability and the user experience while inputting text on these devices is becoming increasingly important. Most conventional touch screen keyboards on mobile devices rely heavily on visual feedback, while auditory feedback seldom includes any useful information about what is being inputted by the user. The auditory feedback usually simply replicates the sounds produced by a physical keyboard. This paper describes the development of an enhanced auditory feedback mechanism for a Korean touch screen keyboard called the enhanced auditory feedback (EAF) mechanism. EAF has subtle phonetic auditory feedback generated using the acoustic phonetic features of human speech. While typing with EAF, users can acquire non-invasive auditory clues about the keys pressed. In this work, we compare conventional auditory feedback for a touch screen keyboard used in touch screen mobile devices with that of EAF and explore the possibility of using enhanced auditory feedback for touch screen keyboards.     

A Study of Pointing Performance of Elderly Users on Smartphones

The number of global smartphone users is rapidly increasing. However, the proportion of elderly persons using smartphones is lower than that of other age groups because they feel it is difficult to use touch screens. There have only been a few studies about usability and elderly smartphone users or designs for them. Based on this background, we studied the pointing action of elderly users, which is a basic skill required to use touch screens on smartphones. We reviewed previous works to determine specific research methods and categorized them into three groups: (a) effect of target size and spacing on touch screen pointing performance, (b) effect of age on pointing performance, and (c) feedback of touch screens. To investigate the touch screen pointing performance of elderly, we conducted two experiments. In the first experiment, 3 target sizes (5 mm, 8 mm, and 12 mm) and 2 target spacings (1 mm, 3 mm) were evaluated. Adding to that, we analyzed whether touch screen pointing performance is dependent on the location of the target. In the second experiment, 3 types of feedback (auditory, tactile, and audiotactile) were evaluated. The results show that (a) pointing performance of elderly was significantly influenced by size, spacing, and location of target, and (b) the performance was higher in audiotactile feedback condition. We expected that these results can contribute to the design of smartphone applications for elderly users.     

Iterative SNR estimation using a priori information

A class iterative signal-to-noise ratio (SNR) estimation algorithm is proposed in this paper. The data samples are governed by a given distribution with a priori. The expectation maximization (EM) algorithm is applied to iteratively maximize the likelihood function so as to realize the SNR estimation. Cramer–Rao bounds (CRB) with different a priori are compared for binary phase shift keying and orthogonal phase shift keying systems, which show the potential of the SNR estimator in turbo-like systems. In high-order modulations, simulation results show that the reduced-complexity iterative method with equal a priori has better performance in middle or high SNR region than the foregone ones. Moreover, the new method with feedback information is the best when its iteration number is 4 and extrinsic information larger than 0.4. These methods are applied in the bit-interleaved coded modulation with iterative decode (BICM-ID) system to validate the effect of the proposed methods.     

Comparison of the impact of some Minkowski metrics on VQ/GMM based speaker recognition

This paper evaluates the impact of three special forms of the Minkowski metric (Euclidean, City Block, and Chebychev distances) on the performance of the conventional vector quantization (VQ) and Gaussian mixture model (GMM) based closed-set text-independent speaker recognition systems, in terms of recognition rate and confidence on decisions. For the VQ based system, evaluations are carried out using the two most common clustering algorithms, LBG and K-means, and it is revealed which clustering algorithm and distance pair should be used to exploit the best attribute of both to achieve the best recognition rate for a given codebook size. In the case of GMM based system, we introduce the metrics into the GMM using a concatenation of the LBG and K-means algorithms in estimating the initial mean vectors, to which the system performance is sensitive, and explore their impact on system performance. We also make comparison of results obtained from evaluations on clean speech (TIMIT) and telephone speech databases (NTIMIT and NIST2001) with the modern classifiers VQ-UBM and GMM-UBM. It is found that there are cases where conventional VQ based system outperforms the modern systems. Moreover, the impact of distance metrics on the performance of the conventional and modern systems depends on the recognition task imposed (verification/identification).     

A graphical-based password keystroke dynamic authentication system for touch screen handheld mobile devices

Since touch screen handheld mobile devices have become widely used, people are able to access various data and information anywhere and anytime. Most user authentication methods for these mobile devices use PIN-based (Personal Identification Number) authentication, since they do not employ a standard QWERTY keyboard for conveniently entering text-based passwords. However, PINs provide a small password space size, which is vulnerable to attacks. Many studies have employed the KDA (Keystroke Dynamic-based Authentication) system, which is based on keystroke time features to enhance the security of PIN-based authentication. Unfortunately, unlike the text-based password KDA systems in QWERTY keyboards, different keypad sizes or layouts of mobile devices affect the PIN-based KDA system utility. This paper proposes a new graphical-based password KDA system for touch screen handheld mobile devices. The graphical password enlarges the password space size and promotes the KDA utility in touch screen handheld mobile devices. In addition, this paper explores a pressure feature, which is easy to use in touch screen handheld mobile devices, and applies it in the proposed system. The experiment results show: (1) EER is 12.2% in the graphical-based password KDA proposed system. Compared with related schemes in mobile devices, this effectively promotes KDA system utility; (2) EER is reduced to 6.9% when the pressure feature is used in the proposed system. The accuracy of authenticating keystroke time and pressure features is not affected by inconsistent keypads since the graphical passwords are entered via an identical size (50 mm × 60 mm) human–computer interface for satisfying the lowest touch screen size and a GUI of this size is displayed on all mobile devices.     

Optimization of string length for spoken digit input with error correction

No matter how much the performance of speech recognition systems improves, it is unlikely that perfect recognition will always be possible in practical situations. Environmental sounds will interfere with the recognition. In such circumstances it is sensible to provide feedback so that any errors which occur may be detected and corrected. In some situations, such as when the eyes are busy or over the telephone, it is necessary to provide feedback auditorily. This takes time, so the most efficient procedure should be determined. In the case of entering digits into a computer the question arises as to whether feedback should be provided after each digit has been spoken or after a string of digits has been recognized. It has been be found that this depends upon the accuracy of the recognizer and on the times required for recognizing the utterances and for changing from recognizing to synthesizing speech.     

Accuracy of non-visual directional pointing with various manual input devices

In a self-testing vision screener, examinees use an input device for pointing the orientation of the targets, which are presented inside the vision screener. Examinees operate the input device without visual feedback. In the present study, the suitability of pointing devices was evaluated for conditions such as are present in a self-testing vision screener. The evaluation consisted of an experimental assessment of pointing accuracy and recording subjective ratings while using the various devices. Six commercially available computer input devices – a joystick, a gamepad, a trackball, two track pads and a PC mouse - were evaluated under visual conditions similar to those that would be present when using a self-testing vision screener.Pointing accuracy was found to vary significantly with the type of device (F(3.2, 93.1) = 3.937, p = 0.009) and the effect of the device on pointing accuracy was important (partial η² = 0.120). The most accurate pointing was achieved when participants used the joystick. Using the joystick, a mean of 96.8% (SD = 4.3%) of pointing trials resulted in the correct orientation. If only diagonal orientations are considered, the correct pointing rate increased to a mean of 99.5% (SD = 1.5%) when using the joystick.In terms of the subjective ranking, the gamepad and the joystick achieved the best and the second best ranks respectively, whereas the trackball was the least preferred device.Based on our findings, we recommend using a joystick as an input device in pointing tasks in order to minimize the effects of suboptimal visual feedback on motor performance. As for the particular case of testing visual acuity, various procedures are suggested. Thus, the effect of suboptimal visual feedback on the outcome of the acuity test is reduced.     

Effects of ambient illuminance on users' visual performance using various electronic displays

Abstract— This study investigated the effect of ambient illuminance (50, 500, 1500, 3000, 6000, and 9000 lx) on participants' visual performance using four electronic displays (conventional LCD under transmissive mode, conventional LCD under reflective mode, Ch‐LC display, and E‐ink display). Analysis results indicate that participants' visual performance shows significant difference under various ambient illuminance and electronic displays. The interaction between ambient illuminance and electronic display also has significant effect on participants' visual performance. When participants use the conventional LCD under transmissive mode, ambient luminance has no significant effect on participants' visual performance. However, participants' visual performance is significantly different under various ambient illuminances using the conventional LCD under reflective mode, Ch‐LC display, and E‐ink display. The conventional LCD under transmissive mode is the only choice at a lower illuminance of 50 lx. Higher illuminance (500 lx) for E‐ink displays may result in as good a performance as the conventional LCD under transmissive mode; nevertheless, much higher illuminance (1500 lx) for the conventional LCD under reflectance mode and Ch‐LC display may achieve better performance.     

The influence of performance standards and feedback on speed and accuracy in an electronically monitored data‐entry task

This study examined performance effects of using electronic performance monitoring (EPM) and feedback to induce compliance with speed and accuracy standards in a data entry task. The study focused on subjects who had difficulty meeting a preestablished data entry speed standard. Subjects performed a data‐entry task for 3 days. On the 1st (baseline) day, no performance standards were imposed, and all subjects were instructed to work at their normal speed and accuracy levels. For the 2nd and 3rd days of the experiment, subjects were assigned at random to one of two groups. In an experimental group, EPM and feedback were used to induce compliance with preestablished speed and accuracy standards. In a control group, subjects were unaware of EPM and received no feedback; they were instructed to continue working at their normal speed and accuracy levels. The introduction of EPM work management in the experimental group led to significant increases in data‐entry speed that were accompanied by significant increases in data‐entry errors. In addition, data‐entry errors produced by experimental subjects increased significantly over time during the workdays in which EPM work management was employed. These effects are discussed in terms of relevant research on goal setting and feedback utilization. The results suggest that when performance standards and feedback that emphasize speed more than accuracy are applied in EPM‐managed work settings, speed increments may be offset by decrements in work quality.     

Measurement-integrated simulation of wall pressure measurements using a turbulent model for analyzing oscillating orifice flow in a circular pipe

The development of a highly functionalized orifice flowmeter with high accuracy under realistic conditions is desired. This paper presents a method for analyzing oscillating air flow through an orifice in a circular pipe. A measurement-integrated (MI) simulation using a standard k–ε model was used to reduce the computation time. In a previous study, the feedback law of the MI simulation was determined by considering the effect of the computational fluid dynamics (CFD) grid on contracted flow. However, the previous method required the measurement of inlet flow rate, which is not feasible in many applications. Therefore, an MI simulation was proposed that only requires wall pressures, which are much simpler to measure than flow rate. In this MI simulation, the wall pressure downstream of an orifice was measured, and a new proportional–integral controller feedback algorithm was developed to control the inlet flow rate in the computed flow field. The proposed MI simulations were performed for steady and oscillatory flow rates up to 10 Hz. It was found that this MI simulation provides accurate solutions at a significantly shorter computation time than conventional CFD analysis.     

Training Wideband Acoustic Models Using Mixed-Bandwidth Training Data for Speech Recognition

One serious difficulty in the deployment of wideband speech recognition systems for new tasks is the expense in both time and cost of obtaining sufficient training data. A more economical approach is to collect telephone speech and then restrict the application to operate at the telephone bandwidth. However, this generally results in suboptimal performance compared to a wideband recognition system. In this paper, we propose a novel expectation-maximization (EM) algorithm in which wideband acoustic models are trained using a small amount of wideband speech and a larger amount of narrowband speech. We show how this algorithm can be incorporated into the existing training schemes of hidden Markov model (HMM) speech recognizers. Experiments performed using wideband speech and telephone speech demonstrate that the proposed mixed-bandwidth training algorithm results in significant improvements in recognition accuracy over conventional training strategies when the amount of wideband data is limited