Usability Textual Data Analysis: A Formulaic Coding Think-Aloud Protocol Method for Usability Evaluation

Think-aloud protocols are among the most standard methods for usability evaluation, which help to discover usability problems and to examine improvements because they provide direct information on a user's thinking and cognitive processes; however, it is often difficult to determine how to analyze the data to identify usability problems because there is no formulaic analysis procedure for textual data. Therefore, the analysis is time-consuming, and the quality of the results varies depending on an analyst's skills. In the present study, the author proposes a formulaic analysis think-aloud protocol method that specifies the procedure for analyzing participants' verbal responses during usability tests. The aim of the proposed think-aloud protocol method was to deliver an explicit procedure using step coding (SCAT) and 70 design items for textual data analysis, and then, the method was applied to a case study of usability evaluation to confirm that the method could extract the target system's problems. By using step coding and 70 design items, the process of extracting usability problems from textual data was made explicit, and the problems were extracted analytically. In other words, the proposed method was less ambiguous. Once a formulaic analysis procedure was established, textual data analysis could be performed easily and efficiently. The analysis could be performed without hesitation after data acquisition, and there were fewer omissions. In addition, it is expected that the procedure would be easy to use, even for novice designers

Value-Centered Design Process for User Experience Enhancement: A Case Study in the Development of a Notebook PC

Since 2000, in the planning and development of products and services, providing users with a better experience when using products and services has become essential, resulting in a growing need for value-centered design that focuses on providing users with more attractive experience values. In this article, we introduce the value-centered product development process that has been used in the planning and development of notebook PCs, focusing on the experience value provided to the user

Effects of Asymmetry between Design Models and User Models on Subjective Comprehension of User Interface

This study attempted to discuss the design principles for enhancing usability in terms of asymmetry of mental models between users and designers. If the user model is asymmetrical to the design model, i.e., the degree of agreement between models is low and the user's mental model is not compatible with the actual system, the user cannot operate the system properly, which may cause errors. The aim of this study was to investigate the characteristics of users who have asymmetrical mental models and identify what such users did not understand. Twenty-four subjects participated in an experiment that involved a digital camera operation task and mental model tests that measure the level of the agreement of the mental model construction in terms of functional and structural models. Initially, the participants were grouped based on mental model test scores: symmetrical mental model group (n = 17) and asymmetrical mental model group (n = 7). Then, the groups were compared in terms of performance and subjective comprehension. The comparison indicated that the symmetrical mental model group performed more quickly and accurately than the asymmetrical group. The results also confirmed that the asymmetrical mental model group had a lower level of comprehension in terms of understanding the device status, detecting and responding to device status changes, and understanding the hierarchical structure of the screen

Cross-Cultural Analysis of Top Page Design Among Brazilian, Chinese, Japanese and United States Web Sites

The aim of present study was to reveal the differences of web design including cultural preference among the four countries that have different cultures. Twenty local municipal sites were randomly chosen from United States, Japan, China, and Brazil. The characteristics of these web sites was investigated from viewpoint of the following seven categories: (1) text, (2) layout, (3) navigation, (4) multimedia, (5) links, (6) items location, (7) color. When the web site had each factor, the researcher gave a "1" for that factor. Chi-square goodness-of-fit test was performed to compare the percentage of "0" or "1" of each factor among the four countries. Additionally, the correspondence analysis was performed to grasp the characteristics of each country. The characteristics of the top page design of the four countries were grasped based on these analyses

Sensitivity of PERCLOS70 to Drowsiness Level: Effectiveness of PERCLOS70 to Prevent Crashes Caused by Drowsiness

It has been reported that many crashes are caused by drowsiness. Thus, it is critical to predict the occurrence of severe drowsiness that may result in a crash by means of an effective measure. The aim of this study was to investigate whether percentage closure (PERCLOS) of 70% was useful for evaluating drowsiness level of individual drivers and preventing crashes caused by drowsy driving using a driving simulator system. The first experiment measured PERCLOS70 during both aroused and drowsy states in a driving simulator task and investigated how PERCLOS70 changes when a participant fell asleep. In the second experiment, we measured PERCLOS70 and investigated the relation between PERCLOS70 and Karolinska Sleepiness Scale (KSS) ratings during a simulated driving task. The aggregated mean PERCLOS70 was significantly higher when participants fell asleep than when they were aroused. This tendency was also observed for individual participants. The aggregated mean PERCLOS70 was found to be sensitive to changes in KSS scores and increased with increasing KSS score. Linear trend analysis revealed a significant increasing trend for PERCLOS70 as a function of the KSS rating. This tendency was also observed for individual participants. PERCLOS70 was found to be sensitive to the drowsiness level both for data aggregated across all participants and data for individual participants. The main findings of the two experiments reported herein suggest that PERCLOS70 can be used effectively to evaluate drowsiness of individual drivers and prevent crashes caused by drowsy driving

Delayed Evacuation after a Disaster Because of Irrational Prediction of the Future Cumulative Precipitation Time Series under Asymmetry of Information

This study investigated biased prediction of cumulative precipitation, using a variety of patterns of histories of cumulative precipitation, to explore how such biased prediction could delay evacuation or evacuation orders. The irrationality in predicting the future of cumulative precipitation was examined to obtain insights into the causes of delayed evacuation or evacuation orders using a simulated prediction of future cumulative precipitation based on the cumulative precipitation history. Anchoring and adjustment, or availability bias stemming from asymmetry of information, was observed in the prediction of cumulative precipitation, and found to delay evacuation or evacuation orders

Highly stable meso-diaminopimelate dehydrogenase from an Ureibacillus thermosphaericus strain A1 isolated from a Japanese compost: purification, characterization and sequencing

We screened various thermophiles for meso-diaminopimelate dehydrogenase (meso-DAPDH, EC 1.4.1.16), which catalyzes the NAD(P)-dependent oxidative deamination of meso-diaminopimelate, and found the enzyme in a thermophilic bacterium isolated from compost in Japan. The bacterium grew well aerobically at around 55°C and was identified as Ureibacillus thermosphaericus strain A1. We purified the enzyme about 47-fold to homogeneity from crude cell extract using five successive purification steps. The molecular mass of the purified protein was about 80 kDa, and the molecule consists of a homodimer with the subunit molecular mass of about 40 kDa. The optimum pH and temperature for the catalytic activity of the enzyme are about 10.5 and 65°C, respectively. The enzyme is highly selective for meso-diaminopimelate as the electron donor, and NADP but not NAD can serve as the electron acceptor. The Km values for meso-diaminopimelate and NADP at 50°C and pH 10.5 are 1.6 mM and 0.13 mM, respectively. The nucleotide sequence of this meso-DAPDH gene encodes a 326-amino acid peptide. When the gene was cloned and overexpressed in Escherichia coli Rosetta (DE3), the specific activity in the crude extract of the recombinant cells was about 18.0-fold higher than in the extract from U. thermosphaericus strain A1. This made more rapid and simpler purification of the enzyme possible

Development of an Eye-Gaze Input System With High Speed and Accuracy through Target Prediction Based on Homing Eye Movements

In this study, a method to predict a target on the basis of the trajectory of eye movements and to increase the pointing speed while maintaining high predictive accuracy is proposed. First, a predictive method based on ballistic (fast) eye movements (Approach 1) was evaluated in terms of pointing speed and predictive accuracy. In Approach 1, the so-called Midas touch problem (pointing to an unintended target) occurred, particularly when a small number of samples was used to predict a target. Therefore, to overcome the poor predictive accuracy of Approach 1, we developed a new predictive method (Approach 2) using homing (slow) eye movements rather than ballistic (fast) eye movements. Approach 2 overcame the disadvantage (inaccurate prediction) of Approach 1 by shortening the pointing time while maintaining high predictive accuracy

Irrationality of Attitudes toward Safety under Complexity and Uncertainty Leading to Asymmetry of Information

This study investigated how complexity and uncertainty, the probability of accidents, and the probability of financial trouble affected individuals' recognition of validity of irrational risk-seeking decisions. As a result of conducting a multiple regression analysis on the validation score for irrational risk-seeking alternative obtained by a questionnaire survey, we found that the validity score for an irrational risk-seeking alternative was higher when both complexity and uncertainty were high than when both complexity and uncertainty were low, which means that high complexity and high uncertainty in the situation of decision making more readily leads to an irrational risk-seeking behavior that might trigger a major accident. Beyond complexity and uncertainty, the damage of major accident alpha, the decrease of the probability of major accidents and the increase of the probability of financial trouble (economic factor) were also found to promote the choice of irrational risk-seeking alternatives. Some implications for safety management under high complexity and uncertainty are discussed

Effectiveness of Tactile Warning and Voice Command for Enhancing Safety of Drivers

Safety is impaired when drivers are required to perform main driving task (tracking of own car, distance maintenance between own car and a leading car, and response to target objects) and secondary task simultaneously, for example, responding to target cars on the road while operating in-vehicle equipment. A two-factor (presence or absence of tactile warning by input modality (no secondary task, voice command for a secondary task, and manual input for a secondary task)) within-subject design of ten licensed males was used to investigate how to compensate for safety impairments (decreased performance of a main and a secondary task such as increased tracking error during driving or increased reaction time to target cars on the road). We investigated whether the use of tactile warnings transmitted via left and right thighs for detecting road objects and voice command to operate in-vehicle equipment could compensate for safety impairments such as the increased reaction time to target cars on the road, the increase of detection error of target cars, or increased tracking error in driving. The accuracy and speed of responses to target cars encountered during driving were reduced when a driver was asked to perform the main and the secondary task simultaneously compared to situations performing only the main driving task (tracking, distance maintenance, and response to target cars). The availability of a tactile warning system for road objects compensated for these diminished performance measures, including slower response times and the increased detection error of target cars. Likewise, voice command contributed to enhanced performance of the main driving task such as decrease of tracking error