The success of an online transaction with a government organization depends on citizen's willingness to share personal data relevant for the transaction. However, disclosing personal data online is oftentimes considered risky. It has been substantiated in a number of empirical studies that perceptions of the risks involved in sharing personal data in the virtual environment could hinder Internet users from engaging in online transactions that require the disclosure of personal data. Results of a large-scale online survey with 2,202 Dutch Internet users reveal that trust in government organizations is a very important determinant of personal data disclosure intention among users with and without e-government experience. Low perceptions of risks, high expectations of the benefits of e-government services, and strong beliefs in the adequacy of legal protection mechanisms could also positively influence users' intention to share personal data for e-government services. The negative relation between trust and risk perceptions is also established, as citizens' trust in government organizations could reduce perceptions of the risks involved in disclosing personal data online.

The retrospective think-aloud method, in which participants work in silence and verbalize their thoughts afterwards while watching a recording of their performance, is often used for the evaluation of websites. However, participants may not always be able to recall what they thought, when they only see few visual cues that help them remembering their task execution process. In our study we complemented the recording of the performance with a gaze trail of the participant" eye movements, in order to elicit more verbalizations. A comparison was made between the traditional retrospective think-aloud protocols and the variant with eye movements. Contrary to our expectations, no differences were found between the two conditions on numbers of problems, the ways these problems were detected, and types of problems. Two possible explanations for this result are that eye movements might be rather confronting and distracting for participants, and the rather generic way of probing we used. The added value might be stronger when specific questions are asked, based on the observed eye movements. Implications for usability practitioners are discussed in the conclusions of this paper.

This paper describes a comparative study of three usability test approaches: concurrent think-aloud protocols, retrospective think-aloud protocols, and constructive interaction. These three methods were compared by means of an evaluation of an online library catalogue, which involved four points of comparison: number and type of usability problems detected; relevance of the problems detected; overall task performance; and participant experiences. The results of the study showed that there were only few significant differences between the usability test approaches, mainly with respect to manner of problem detecting, task performance and participant experience. For the most part, the usability methods proved very much comparable, revealing similar numbers and types of problems that were equally relevant. Taking some practical aspects into account, a case can be made for preferring the concurrent think-aloud protocols over the other two methods.

Think-aloud protocols are a dominant method in usability testing. There is, however, only little empirical evidence on the actual validity of the method. This paper describes an experiment that compares concurrent and retrospective think-aloud protocols for a usability test of an online library catalogue. There were three points of comparison: usability problems detected, overall task performance, and participant experiences. Results show that concurrent and retrospective think-aloud protocols reveal comparable sets of usability problems, but that these problems come to light in different ways. In retrospective think-aloud protocols, more problems were detected by means of verbalisation, while in concurrent think-aloud protocols, more problems were detected by means of observation. Moreover, in the concurrent think-aloud protocols, the requirement to think aloud while working had a negative effect on the task performance. This raises questions about the reactivity of concurrent think-aloud protocols, especially in the case of high task complexity.