Paul van Schaik

The effect of text and background colour on visual search of Web pages

Usability and visual impact in Web pages are not necessarily compatible ideals. This paper investigates the effect of colour on the presentation of information in a navigation bar, and aims to contribute towards design guidelines for the use of colour on the Web. We studied the effect of the combination of text and background colour on visual search performance and subjective preference. Twenty-nine participants carried out a visual search task using mock Web pages. Analysis showed that higher contrasts between text and background colour led to faster searching and were rated more favourably. The results are discussed in terms of visual search processes and design recommendations are given.

The effect of spatial layout of and link colour in web pages on performance in a visual search task and an interactive search task

This study aimed to investigate the validity of psychological experimental methods within human-computer interaction research (Carroll, 1989) and to examine design guidelines pertaining to hypertext link colour and positioning of navigation menu frames as part of web documents. The results of past research on both link colour and positioning of menus are mixed and guidelines are usually not based on empirical evidence (Tullis, 1997; Shneiderman, 1997). The study used a repeated measures experimental design. Participants carried out both a visual search task and an interactive search task. Task performance on the two tasks did not to correlate (p > 0.05), indicating that the visual search task may lack external validity. Results of the interactive search task suggest that the design convention of blue links (Nielsen, 1999a) should be retained as responses for blue were found to be significantly quicker than red, F(1, 117) = 14.526, p < 0.001, MScolour = 89.866. Furthermore, an effect of presentation position, F(3, 117) = 8.410, p < 0.001, MSposition = 61.015, was found, with support for menus on the left (Nielsen, 1999a: Campbell & Maglio, 1999) or right (Nielsen, 1999a). Evidence was also found to support the conjecture that experienced Internet users might have formed automatic attention responses to specific web page designs. The need for validation of behavioural and psychometric methods with task performance and the use of cognitive-perceptual-motor modelling are discussed.

Attitudes towards User Experience (UX) Measurement

Abstract User experience (UX), as a recently established research area, is still haunted by the challenges of defining the scope of UX in general and operationalising experiential qualities in particular. To explore the basic question whether UX constructs are measurable, we conducted semi-structured interviews with 10 UX researchers from academia and one UX practitioner from the industry where a set of questions in relation to UX measurement were explored (Study 1). The interviewees expressed scepticism as well as ambivalence towards UX measures and shared anecdotes related to such measures in different contexts. Interestingly, the results suggested that design-oriented UX professionals tended to be sceptical about UX measurement. To examine whether such an attitude prevailed in the HCI community, we conducted a survey – UX Measurement Attitudes Survey (UXMAS) – with essentially the same set of 13 questions used in the interviews (Study 2). Specifically, participants were asked to rate a set of five statements to assess their attitude towards UX measurement, to identify (non)measurable experiential qualities with justifications, and to discuss the topic from the theoretical, methodological and practical perspectives. The survey was implemented in a paper-based and an online format. Altogether, 367 responses were received; 170 of them were valid and analysed. The survey provided empirical evidence on this issue as a baseline for progress in UX measurement. Overall, the survey results indicated that the attitude towards UX measurement was more positive than that identified in the interviews, and there were nuanced views on details of UX measurement. Implications for enhancing the acceptance of UX measures and the interplay between UX evaluation and system development are drawn: UX modelling grounded in theories to link experiential qualities with outcomes; the development of UX measurement tools with good measurement properties, and education within the HCI community to disseminate validated models, and measurement tools as well as their successful applications. Mutual recognition of the value of objective measures and subjective accounts of user experience can enhance the maturity of this area.

The impact of early dementia on outdoor life : a 'shrinking world' ?

This article reports the voices of 22 people with early to moderate dementia and their carers about the use of the outdoor environment. Analysis of semi-structured interviews demonstrates that people with early dementia value the outdoor environment for reasons such as exercise, fresh air, emotional well-being, the opportunity for informal encounters with neighbours and friends and the appreciation of the countryside. Conversely, not being able to go out was associated with feelings of depression. Carers reported that the impact of dementia was to decrease the frequency of outdoor activity and to limit the areas visited to those that were the most familiar. Maintaining outdoor activity is likely to be an effective measure in extending the period of good quality living and might decrease the period when intensive services are required. It should therefore be considered in planning for both residential care and community living in the future.

Exaggerated risk: prospect theory and probability weighting in risky choice

In 5 experiments, we studied precautionary decisions in which participants decided whether or not to buy insurance with specified cost against an undesirable event with specified probability and cost. We compared the risks taken for precautionary decisions with those taken for equivalent monetary gambles. Fitting these data to Tversky and Kahnemans (1992) prospect theory, we found that the weighting function required to model precautionary decisions differed from that required for monetary gambles. This result indicates a failure of the descriptive invariance axiom of expected utility theory. For precautionary decisions, people overweighted small, medium-sized, and moderately large probabilities-they exaggerated risks. This effect is not anticipated by prospect theory or experience-based decision research (Hertwig, Barron, Weber, & Erev, 2004). We found evidence that exaggerated risk is caused by the accessibility of events in memory: The weighting function varies as a function of the accessibility of events. This suggests that peoples experiences of events leak into decisions even when risk information is explicitly provided. Our findings highlight a need to investigate how variation in decision content produces variation in preferences for risk.

Developing a virtual reality based methodology for people with dementia: a feasibility study

The aim of this study was to examine the feasibility of virtual reality (VR) technology for use by persons with dementia (PWD). Data were obtained directly from six PWD regarding their experiences with a virtual environment (VE) of a large outdoor park. A user-centered method was developed to assess: (a) presence; (b) user inputs; (c) display quality; (d) simulation fidelity; and (e) overall system usability. The extent to which PWD could perform four functional activities in the VE was also investigated (e.g., mailing a letter). In addition, physical and psychological well-being of PWD while interacting with the VE was assessed objectively by recording heart rate during the VR sessions and subjectively with discrete questionnaire items and real-time prompts. Symptom profiles associated with simulator sickness were assessed with an adapted version of the Simulator Sickness Questionnaire. The study found that PWD to some extent experienced presence; perceived that objects were realistic and moved naturally; generally felt in control of the interaction; and demonstrated little difficulty using a joystick for navigation. The study also demonstrated that VR is an appropriate medium for assessing functional behavior within the context of an ecologically valid VE. PWD did not experience any significant increase in symptoms associated with simulator sickness, or detriments to their psychological and physical well-being. These findings demonstrated that it is feasible to work in VEs with PWD.

Five psychometric scales for online measurement of the quality of human-computer interaction in web sites

The use of a comprehensive set of psychometric instruments for measuring the quality of interaction in Web sites is proposed. Five existing scales for Web site evaluation, each measuring a key construct in human-computer interaction, were used together. The set of 5 scales demonstrated good distinguishability of factor structure, and all scales possessed adequate reliability. Evidence for validity of the scales was obtained, but additional work is necessary to establish the conditions under which these properties are best demonstrated. Aesthetic quality emerged as a separate scale that moderately correlated with other scales and level of task performance, highlighting the importance of aesthetics in interaction with Web pages. The results suggest the 5 scales can be used to measure the quality of interaction in Web sites for both monitoring and continual improvement of these sites.

A comparison of multi-item Likert and visual analogue scales for the assessment of transactionally defined coping function

Summary: The evaluation and monitoring of interventions that are designed to alleviate psychosocial stress rely largely on subjective assessments of coping as primary outcome measures. The pros and cons of different response formats used to measure coping variables are unexplored; yet arguably, response format is a very important methodological issue for the clinical application and evaluation of psychosocial interventions. This study compared the levels of functional coping and transactional coping patterns assessed with multi-item 7-point Likert Scales (LS) and 65mm Visual Analogue Scales (VAS), within the framework of the Functional Dimensions of Coping (FDC) Scale developed by Ferguson and Cox, 1997. LS yielded significantly higher levels of functional coping for all four subscales, and captured a wider range of transactional coping patterns for the approach, emotion, and avoidance coping functions, than VAS. The authors recommend the use of LS for baseline assessments of transactionally defined copin...

An integrated model of interaction experience for information retrieval in a Web-based encyclopaedia

An experiment, using two versions of a Web site varying in usability, tested three models of user experience: an interaction experience model, a technology acceptance model and an integrated experience-acceptance model. We found that the perceptions of three product attributes (Pragmatic Quality, Hedonic Quality-stimulation and Hedonic Quality-identification) and technology acceptance variables (the beliefs of Perceived Ease of Use, Perceived Enjoyment and Perceived Usefulness, and Intention to Use) are separate underlying psychological dimensions. A positive effect of usability on task performance, interaction experience and acceptance was found. In the interaction experience model, the evaluation of Goodness (overall interaction quality) was less stable and influenced by both Pragmatic Quality and Hedonic Quality, but the evaluation of Beauty was more stable and only influenced by Hedonic Quality. In the technology acceptance model, Perceived Ease of Use was a determinant of Perceived Enjoyment and Perceived Usefulness, and the latter two were independent determinants of Intention to Use. In the integrated model, perceptions of product attributes were independent determinants of beliefs, but evaluations were not independent determinants of Intention to Use. Future modelling work should address a range of interactive systems, information architecture and individual differences.

Design parameters of rating scales for web sites

The effects of design parameters of rating scales on the perceived quality of interaction with web sites were investigated, using four scales (Disorientation, Perceived ease of use, Perceived usefulness and Flow). Overall, the scales exhibited good psychometric properties. In Experiment 1, psychometric results generally converged between two response formats (visual analogue scale and Likert scale). However, in Experiment 2, presentation of one questionnaire item per page was better than all items presented on a single page and direct interaction (using radio buttons) was better than indirect interaction (using a drop-down box). Practical implications and a framework for measurement are presented.