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.

This paper describes a comparative study of three usability test approaches: concurrent thinkaloud 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. q

The exopolysaccharide of Streptococcus thermophilus S3, produced in skimmed milk, is composed of D-galactose and L-rhamnose in a molar ratio of 2:1. The polysaccharide contains 0.4 equiv of O-acetyl groups per repeating unit. Linkage analysis and 1D/2D NMR ( 1 H and 13 C) studies on native and O-deacetylated EPS together with nanoES-CID tandem mass spectrometry studies on oligosaccharides generated by a periodate oxidation protocol, show the polysaccharide to have the following structure:

BackgroundDisease risk calculators are increasingly web‐based, but previous studies have shown that risk information often poses problems for lay users.ObjectiveTo examine how lay people understand the result derived from an online cardiometabolic risk calculator.DesignA qualitative study was performed, using the risk calculator in the Dutch National Prevention Program for cardiometabolic diseases. The study consisted of three parts: (i) attention: completion of the risk calculator while an eye tracker registered eye movements; (ii) recall: completion of a recall task; and (iii) interpretation: participation in a semi‐structured interview.Setting and participantsWe recruited people from the target population through an advertisement in a local newspaper; 16 people participated in the study, which took place in our university laboratory.ResultsEye‐tracking data showed that participants looked most extensively at numerical risk information. Percentages were recalled well, whereas natural frequencies and verbal labels were remembered less well. Five qualitative themes were derived from the interview data: (i) numerical information does not really sink in; (ii) the verbal categorical label made no real impact on people; (iii) people relied heavily on existing knowledge and beliefs; (iv) people zoomed in on risk factors, especially family history of diseases; and (v) people often compared their situation to that of their peers.Discussion and conclusionAlthough people paid attention to and recalled the risk information to a certain extent, they seemed to have difficulty in properly using this information for interpreting their risk.

The think aloud method is widely used in usability research to collect user's reports of the experience of interacting with a design so that usability evaluators can find the underlying usability problems. However, concerns remain about the validity and usefulness of think aloud in usability studies. In this panel we will present current studies of the think aloud method, examine and question its usage in the field, discuss the possible pitfalls that may threaten the validity of the method, and provide comments/suggestions on the application of the method. Panel participants will discuss results drawn from both applied research and basic research.We believe that this panel discussion will be useful for HCI designers and usability practitioners in that it will acquaint them with concerns that people have about the think aloud method and provide them with suggestions for improved use of the method. For HCI or usability researchers, this panel discussion will address the importance of formally investigating currently used or newly designed usability methods.