The past decade has witnessed the emergence of an active visual programming research community.Yet, there has also been a noteworthy shortage of empirical evidence supporting the resulting research. This paper summarizes empirical data relevant to visual programming languages, both to show the current empirical status and to act as a call to arms for further empirical work.

External representations (ERs) are effective in reasoning due to their cognitive and semantic properties. We investigated subjects' use of ERs in their solutions to analytical reasoning problems. Two sources of data were analysed. The first consisted of a large corpus of ERs (`workscratchings') used by students in their solutions to problems administered via paper and pencil tests. The second source of data was collected using switchER, a computer-based system that administered the problems, provided a range of ER construction environments for the subject to choose between and which dynamically logged user--system interactions. SwitchER was developed in order to study the process and time-course of ER use and to investigate the mechanisms (such as ER switching) by which subjects resolve impasses in reasoning. The results showed great diversity of ER use across subjects, allowing the utility of various ERs under differing task conditions to be studied. The range of ERs used by subjects ...

Data modelling reveals the internal structure of an information system, abstracting away from details of the physical representation. We show that entity-relationship modelling, a well-tried example of a data-modelling technique, can be applied to both interactive and non-interactive information artefacts in the domain of HCI. By extending the conventional ER notation slightly (to give ERMIA, Entity-Relationship Modelling for Information Artefacts) it can be used to describe differences between different representations of the same information, differences between user's conceptual models of the same device, and the structure and update requirements of distributed information in a worksystem. It also yields symbolic-level estimates of Card et al.'s (1994) index of `cost-of-knowledge' in an informa- tion structure, plus a novel index, the `cost-of-update'; these symbolic estimates offer a useful complement to the highly detailed analyses of time costs obtainable from GOMS-like...

We present an empirical study investigating collaborative and individual decision-making about data using two different information visualization systems. Based on previous research, one system is considered more transparent than the other in terms of visual representation and functionality. We found that people who worked in groups were more correct in their answers for objective questions, based on searching a large dataset. These results held for the more transparent system, but not the less transparent system. In a second task, groups were more accurate in their results for a free data discovery task. Again, these results held for the more transparent system only. Subjects using this system also produced results that were higher in complexity but judged lower in importance. Groups and individuals did not differ. We suggest that given the right visualization system, groups do better than individuals in finding more accurate results, but not necessarily increased or more meaningful results.

Modern computer systems routinely present information to the user as a combination of text and diagrammatic images, described as "graphical user interfaces". Practitioners and researchers in Human-Computer Interaction (HCI) generally believe that the value of these diagrammatic representations is derived from metaphorical reasoning; they communicate abstract information by depicting a physical situation from which the abstractions can be inferred. This assumption has been prevalent in HCI research for over 20 years, but has seldom been tested experimentally. This thesis analyses the reasons why diagrams are believed to assist with abstract reasoning. It then presents the results of a series of experiments testing the contribution of metaphor to comprehension, problem solving, explanation and memory tasks carried out using a range of different diagrams. The results indicate that explicit metaphors provide surprisingly little benefit for cognitive tasks using diagrams as an external re...

I would like to thank Sean Hurley for helpful discussions of many of the issues considered in this chapter and for comments on an earlier version of the manuscript. I would also like to thank Doug Morse and Kirsten Whitley for examples of the use of diagrams in society throughout history. Correspondence concerning this article should be addressed to Laura R. Novick,

We present an empirical study in which we investigated group vs. individual performance with collaborative information visualization environments (CIVEs), the effects of system transparency on users' performance and the effects of different collaborative settings on CIVE usage. Subjects searched for findings with CIVEs, working either alone, in a collocated dyad using a shared electronic whiteboard, or in a remote dyad using application sharing. Groups answered more questions correctly and took less time with the more transparent CIVE than groups using the less transparent CIVE. We interpret our results to mean that groups have better self-corrective abilities when the system is transparent. We present a stage model to explain the collaborative process of using CIVEs, which accounts for task type, collaborative setting, and system transparency.

Abstract. Hypermedia structures have been integrated with CSCW functionality to develop the DOLPHIN system, an electronic meeting room environment. In this paper, a study is reported investigating how the DOLPHIN environment affects group work. Different aspects of group problem solving were examined to understand the effects of working with hypermedia: the group’s product, cognitive factors, and the group process. The results showed that groups can easily work with hypermedia structures, and that these structures influence groups to produce a different product, to use a different strategy, and to use a different collaborative style, namely of dividing up their labor. The experimental results are explained in a model which suggests the involvement of both procedural and semantic components in hypermedia use. We discuss wider implications of hypermedia for CSCW and group work. Key words. Hypermedia, cooperation support, electronic meeting room, electronic whiteboards, group process, division of labor, collaborative style, evaluation, empirical study 1

networks, like the one shown in Fig. 1, are common in many cultures (although not in the United States). For example (Zaslavsky, 1998), cultures from around the world (e.g., several African countries, The Philippines, England, Columbia, Sri Lanka, and Pueblo Indians in North America) play games in which players take turns moving their counters along the links in a specific network (the network varies across cultures) until one player gets three counters in a row (i.e., on three nodes directly connected along a path). Game boards for several of these games were found carved on the roof of an ancient Egyptian temple, ca. 1300 BCE. In Mozambique, India, and Bangladesh, people play a checkerslike game on a butterfly-shaped network. Early in the 12th century, a Belgian visitor to the Congo Basin in Zaire introduced European mathematicians to the networks used by the Shongo people who live there (Braxton, Gonsalves, Lipner, & Barber, 1995; Zaslavsky, 1973). Shongo children play a game in the sand in which they trace complex networks (e.g., one network has 142 nodes and 251 links)---every link in the network is traversed exactly once without lifting one's finger from the sand. Networks also play an important role in Shongo culture as part of their storytelling and oral traditions. As these people tell stories, they draw networks to represent the events and changes that take place.

Data modelling reveals the internal structure of an information system, abstracting away from details of the physical representation. We show that entity-relationship modelling, a well-tried example of a data-modelling technique, can be applied to both interactive and non-interactive information artefacts in the domain of HCI. By extending the conventional ER notation slightly (to give ERMIA, Entity-Relationship Modelling for Information Artefacts) it can be used to describe differences between different representations of the same information, differences between usersconceptual models of the same device, and the structure and update requirements of distributed information in a worksystem. It also yields symbolic-level estimates of Card et al.s (1994) index of cost-of-knowledge in an information structure, plus a novel index, the cost-of-update; these symbolic estimates offer a useful complement to the highly detailed analyses of time costs obtainable from GOMS-like models. We conclude that, as a cheap, coarse-grained, and easy-to-learn modelling technique, ERMIA usefully fills a gap in the range of available HCI analysis techniques.