a b s t r a c tIn interface development, it is crucial to reflect the users' expectations and mental models. By meeting users' expectations, errors can be prevented and the efficiency of the interaction can be enhanced. Applying these guidelines to website development reveals the need to know where users expect to find the most common web objects like the search field, home button or the navigation. In a preliminary online study with 136 participants, the most common web objects were identified for three web page types: online shops, news portals, and company web pages. These objects were used for the main study, which was conducted with 516 participants. In an online application, prototypical websites had to be constructed by the participants. Data analysis showed that Internet users have distinct mental models for different web page types (online shop, news portal, and company web page). Users generally agree about the locations of many, but not all, web objects. These mental models are robust to demographic factors like gender and web expertise. This knowledge could be used to improve the perception and usability of websites.

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a b s t r a c tIn this study, a simple but important user interface design choice is examined: when marking requiredfields in online forms, should GUI designers stick with the often used asterisk that many form design guidelines cite as the de-facto web standard, or should they choose a colored background as a new design solution to visually signal which input fields are required? An experiment with 24 participants was conducted to test the hypotheses that efficiency, effectiveness and satisfaction ratings of colored required-fields exceed those of asterisk-marked required-fields. Results indicate that colored required field marking leads to fewer errors, faster form fill-in in and higher user satisfaction.

a b s t r a c tThis work explores the possibility of taking the structural characteristics of approaches to interaction design as a basis for the organization of interaction design patterns. The Universal Model of the User Interface (Baxley, 2003) is seen as well suited to this; however, in order to cover the full range of interaction design patterns the model had to be extended slightly. Four existing collections of interaction design patterns have been selected for an analysis in which the patterns have been mapped onto the extended model. The conclusion from this analysis is that the use of the model supports the process of building a pattern language, because it is predictive and helps to complete the language. If several pattern writers were to adopt the model, a new level of synergy could be attained among these pattern efforts. A concluding vision would be that patterns could be transferred freely between pattern collections to make them as complete as possible.