Aline Chevalier

The use of Tholos software for combining measures of mental workload: toward theoretical and methodological improvements.

Mental workload is a concept central to a range of disciplines (including cognitive psychology and ergonomics) that has given rise to various theoretical and methodological debates. As a result, researchers have used a number of techniques for measuring mental workload. Traditionally, three categories of measurement technique have been recognized: performance measures (e.g., the dual-task paradigm), subjective measures (e.g., rating scales), and physiological measures (e.g., heart, respiration, and blink rates). Each technique has advantages and limitations; however, some limitations may prevent an accurate evaluation of the mental workload. In this article, we focus on the benefits of combining multiple measures of mental workload. However, because combining several techniques is a very complex process, we have developed the Tholos software in an attempt to reduce this complexity. This software package uses measures from each of the three categories: a dual-task paradigm with auditory signals; the National Aeronautics and Space Administration task load index (NASA-TLX) scale and its simplified version, the “raw” task load index (RTLX); and physiological (such as pupil-dilation) measurements with which our software can merge results from the dual-task paradigm. To illustrate the benefits of using Tholos, we describe a puzzle-solving experiment in which we combined multiple measures of mental workload. The results indicate the importance of combining multiple measures to build upon the theoretical and methodological foundations of mental workload.

Query strategies during information searching

Three complexity levels of information problems are defined related to psychology domain.40 students in psychology and in other domains performed information problems with an online encyclopedia.Students in psychology performed better than the others, especially for complex problems.Students in psychologies used more relevant strategies than the others.These expertise-related differences are stronger for the complex problems. This study addresses the impact of domain expertise (i.e. of prior knowledge of the domain) on the performance and query strategies used by users while searching for information. Twenty-four experts (psychology students) and 24 non-experts (students from other disciplines) had to search for psychology information from the Universalis website in order to perform six information problems of varying complexity: two simple problems (the keywords required to complete the task were provided in the problem statement), two more difficult problems (the keywords required had to be inferred) and two impossible problems (no answer was provided by the website). The results showed that participants with prior knowledge in the domain (experts in psychology) performed better (i.e. reached more correct answers after shorter search times) than non-experts. This difference was stronger as the complexity of the problems increased. This study also showed that experts and non-experts displayed different query strategies. Experts reformulated the impossible problems more often than non-experts, because they produced new queries with psychology-related keywords. The participants rarely used thematic category tool and when they did so this did not enhance their performance.

Strategy and accuracy during information search on the Web

This study focused on the impact of question complexity and age on information search activity.10 older and 10 younger adults had to answer questions in using a search engine.Younger adults gave more correct answers than older ones for complex questions.Older adults developed fewer efficiency strategies than younger adults.Age-related differences were particularly pronounced for complex questions. The present study addressed age-related differences in performance and strategies while searching for information on the Web while considering specific processes involved in the search activity on the Internet. To this end, 10 older and 10 younger adults were instructed to use Google to find information. The search questions varied and increased in complexity: three simple questions (participants had to use the keywords provided in the questions), three difficult questions (participants had to infer new keywords to find correct answers), and three impossible questions (no answer existed). The results showed that older participants were less accurate and used fewer efficient strategies compared to younger participants. The differences increased as a function of question complexity. Moreover, older participants tended to focus on the evaluation of the results provided by Google at the expense of opening up and examining websites. In contrast, younger participants controlled their own activities more often, thus allowing them to improve their strategies and obtain higher performances, contrary to older participants who used the same strategies regardless the complexity of the search question.

Articulation of web site design constraints: Effects of the task and designers' expertise

Abstract This paper aims at contributing to a better understanding of the cognitive activities of web site designers and, more precisely, their articulation and satisfaction of various design constraints. In this paper, we first present an experiment in which professional and novice designers have to evaluate a web site developed for reflecting usability errors identified in web sites. Then, the results obtained in this evaluation task are compared with results previously obtained in a design task, in which professional and novice designers had to create a web site. Data analyses focused on the number and nature of constraints articulated by designers in these two types of tasks (evaluation vs design). In particular, we distinguished constraints linked with the client of the site and constraints linked with the future web users. The obtained results show effects of both the level of expertise and the task. While designing, all of the designers focused mainly on constraints linked with the client. In contrast, while evaluating the web site, novices focused on constraints linked with the user, whereas professionals shared their attention between these two kinds of constraints (client vs user-oriented constraints). Based on these results, we conclude with ways for supporting designers’ activities.

The influence of the search complexity and the familiarity with the website on the subjective appraisal of aesthetics, mental effort and usability

The user experience is defined as ‘a persons perceptions and responses that result from the use and/or anticipated use of a product, system or service’ (ISO FDIS 9241-210, 2009) [Ergonomics of human system interaction Ergonomics of human system interaction – Part 210: human-centered design for interactive systems (formerly known as 13407). Switzerland: International Organization for Standardization]. Accordingly, some authors have argued that an interactive system has to be evaluated not only with regard to its usability and utility levels, but also with regard to emotional, attractiveness, and aesthetic levels. These last aspects play a substantial role on the general assessment of such systems and on the satisfaction of users. Some studies focused on the immediate aesthetic subjective perception of systems, on their subjective usability and preference perceptions. However, few studies, at least to our knowledge, have been focused on the reverse, that is, on the effect of difficulties experienced by individuals in using systems on the aesthetic appraisal. The present study aimed at determining the role of familiarity level with the website and the search complexity on the search performance and post-experiment appraisals of aesthetics, usability, and mental effort. The main results revealed that the search complexity affected negatively search performance, whereas the familiarity level affected only the re-reading of the search questions. The post-use assessments of aesthetics, mental effort, and usability satisfaction were affected by search performance. In addition, these variables were correlated except the expressive aesthetics, which seemed to be independent from the search performance and other subjective appraisals. Then, we discuss these findings in line with prior studies and present future ways of research.

Searching for information on the web

Prior domain knowledge improves older adults query and navigation strategies and copes with the age-related decline of cognitive flexibility.Unlike prior results, older adults were outperformed by young ones in open-ended information problems.In open-ended information problems, older adults did not benefit from their prior knowledge and produced semantically less relevant queries as compared to fact-finding problems. This study focuses on the impact of age, prior domain knowledge and cognitive abilities on performance, query production and navigation strategies during information searching. Twenty older adults and nineteen young adults had to answer 12 information search problems of varying nature within two domain knowledge: health and manga. In each domain, participants had to perform two simple fact-finding problems (keywords provided and answer directly accessible on the search engine results page), two difficult fact-finding problems (keywords had to be inferred) and two open-ended information search problems (multiple answers possible and navigation necessary). Results showed that prior domain knowledge helped older adults improve navigation (i.e. reduced the number of webpages visited and thus decreased the feeling of disorientation), query production and reformulation (i.e. they formulated semantically more specific queries, and they inferred a greater number of new keywords).

Modeling and predicting information search behavior

This paper looks at two limitations of cognitive models of web-navigation: first, they do not account for the entire process of information search and second, they do not account for the differences in search behavior caused by aging. To address these limitations, data from an experiment in which two types of information search tasks (simple and difficult), presented to both young and old participants was used. We found that in general difficult tasks demand significantly more time, significantly more clicks, significantly more reformulations and are answered significantly less accurately than simple tasks. Older persons inspect the search engine result pages significantly longer, produce significantly fewer reformulations with difficult tasks than younger persons, and are significantly more accurate than younger persons with simple tasks. We next used a cognitive model of web-navigation called CoLiDeS to predict which search engine result a user would choose to click. Old participants were found to click more often only on search engine results with high semantic similarity with the query. Search engine results generated by old participants were of higher semantic similarity value (computed w.r.t the query) than those generated by young participants only in the second cycle. Match between model-predicted clicks and actual user clicks was found to be significantly higher for difficult tasks compared to simple tasks. Potential improvements in enhancing the modeling and its applications are discussed.

Using the MetroWeb tool to improve usability quality of Web sites

This work addresses the question of supporting Web designers in considering usability in their work in order to foster user-centered design of Web sites. With the MetroWeb tool that is described in this paper, designers can access usability guidelines contained in usability knowledge bases, and use them to design a particular Web site based on these usability guidelines. MetroWeb consists of a Java-based application helping usability experts to gather usability guidelines coming from different sources and to organize them in a structured way. It then provides designers with guidance in using these guidelines according to a semantic network of concepts structured around the notion of guideline, such as ergonomic criteria, development phase, bibliographic reference, type of Web site, type of Web page, etc. A first experiment was conducted with professional Web designers in order to evaluate their appreciation of the MetroWeb tool. They had to create two Web pages with or without the support of MetroWeb. The main results showed that designers using MetroWeb took into account more usability guidelines and made Web pages with less usability errors than designers without MetroWeb.

The effects of ageing and website ergonomic quality on internet information searching

ABSTRACT Since the 1990s, the number of websites and web users, especially older users, has increased extensively. Despite the rapid growth in the number of websites, a significant number of ergonomic violations still hinder the information search activity performed by web users. As ageing is associated with reduced working memory capacity, inhibition failure, slowing of processing speed and more generally impaired executive functioning, older adult web users may experience difficulties while searching for information, especially when the website includes ergonomic violations, such as usability and accessibility violations. In this experiment, the navigation activities of younger and older web users were compared while they were searching for information on a website that met ergonomic guidelines and on a website that included ergonomic violations. The participants then performed a free, delayed-recall task to assess their mental representation of the website they had just navigated. The main findings showed that ageing had a negative impact on search performance but few effects on mental representation built by participants. On the contrary, the ergonomic quality of the website had an impact on search performance and mental representation built by the participants.

Searching for Information on the World Wide Web with a Search Engine: A Pilot Study on Cognitive Flexibility in Younger and Older Users

This pilot study investigated the age-related differences in searching for information on the World Wide Web with a search engine. 11 older adults (6 men, 5 women; M age = 59 yr., SD = 2.76, range = 55–65 yr.) and 12 younger adults (2 men, 10 women; M = 23.7 yr., SD = 1.07, range = 22–25 yr.) had to conduct six searches differing in complexity, and for which a search method was or was not induced. The results showed that the younger and older participants provided with an induced search method were less flexible than the others and produced fewer new keywords. Moreover, older participants took longer than the younger adults, especially in the complex searches. The younger participants were flexible in the first request and spontaneously produced new keywords (spontaneous flexibility), whereas the older participants only produced new keywords when confronted by impasses (reactive flexibility). Aging may influence web searches, especially the nature of keywords used.