The Effects of Visual Information on Users' Mental Models: An Evaluation of Pathfinder Analysis as a Measure of Icon Usability

Research has shown that individuals' knowledge structures change as a result of learning and experience. This article investigates the possibility that the content of graphical user interfaces can play a role in determining the nature of the knowledge structures users develop. Users employed either concrete, abstract, or arbitrary icon sets in a computer-based problem-solving task. The effects of these icons were assessed using standard measures of performance. On the basis of the assumption that users' mental models should be better if appropriate icons were presented on the interface, Pathfinder analysis was used to elicit users' knowledge structures as they gained experience with the interface. The efficacy of this measure was then compared with performance measures. Our findings show that users' knowledge structures do depend on the nature of the graphical information presented at the interface but do not rely as much on the use of the visual metaphor as previously thought. Although most measures were sensitive to initial differences between icon sets, only some measures were sensitive to the long-term differences that remained after users had gained experience with the icon set. The implications of these findings for interface design are discussed

The Effects of Visual Information on Users' Mental Models: An Evaluation of Pathfinder Analysis as a Measure of Icon Usability

Research has shown that individuals' knowledge structures change as a result of learning and experience. This article investigates the possibility that the content of graphical user interfaces can play a role in determining the nature of the knowledge structures users develop. Users employed either concrete, abstract, or arbitrary icon sets in a computer-based problem-solving task. The effects of these icons were assessed using standard measures of performance. On the basis of the assumption that users' mental models should be better if appropriate icons were presented on the interface, Pathfinder analysis was used to elicit users' knowledge structures as they gained experience with the interface. The efficacy of this measure was then compared with performance measures. Our findings show that users' knowledge structures do depend on the nature of the graphical information presented at the interface but do not rely as much on the use of the visual metaphor as previously thought. Although most measures were sensitive to initial differences between icon sets, only some measures were sensitive to the long-term differences that remained after users had gained experience with the icon set. The implications of these findings for interface design are discussed

Social presence and dishonesty in retail

Self-service checkouts (SCOs) in retail can benefit consumers and retailers, providing control and autonomy to shoppers independent from staff, together with reduced queuing times. Recent research indicates that the absence of staff may provide the opportunity for consumers to behave dishonestly, consistent with a perceived lack of social presence. This study examined whether a social presence in the form of various instantiations of embodied, visual, humanlike SCO interface agents had an effect on opportunistic behaviour. Using a simulated SCO scenario, participants experienced various dilemmas in which they could financially benefit themselves undeservedly. We hypothesised that a humanlike social presence integrated within the checkout screen would receive more attention and result in fewer instances of dishonesty compared to a less humanlike agent. This was partially supported by the results. The findings contribute to the theoretical framework in social presence research. We concluded that companies adopting self-service technology may consider the implementation of social presence in technology applications to support ethical consumer behaviour, but that more research is required to explore the mixed findings in the current study.<br/

Hybridization Assays Using an Expressible DNA Fragment Encoding Firefly Luciferase as a Label

We report the use of a new label, an expressible enzymecoding DNA fragment, for nucleic acid hybridization assays. The DNA label contains a firefly luciferase coding sequence downstream from a T7 RNA polymerase promoter. The target DNA (200 bp) is denatured and hybridized simultaneously with two oligonucleotide probes. One of the probes is immobilized in microtiter wells, via the digoxigenin/anti-digoxigenin interaction, and the other probe is biotinylated. After completion of the hybridization, the hybrids are reacted with a streptavidin-luciferase DNA complex. Subsequently, the solid-phase bound DNA is expressed by coupled transcription/ translation. The synthesized luciferase catalyzes the luminescent reaction of luciferin with O 2 and ATP. The luminescence is linearly related to the amount of target DNA in the range of 5-5000 amol. The CVs obtained for 20 and 100 amol of target are 6.5% and 10.8%, respectively (n ) 4). The specific and strong interaction between two complementary nucleic acid strands forms the basis for the development of hybridization assays. Hybridization methodology is emerging as the most promising area in laboratory medicine and has transformed the way clinical testing is realized. Previous tests have been based on the monitoring of gene products, i.e., phenotypic markers, such as oncoproteins, viral antigens, etc. In contrast, current laboratory tests that are based on hybridization allow the analysis of disease at the nucleic acid level. Thus, pre-or postnatal diagnosis of genetic disease can be accomplished by hybridization of the patient&apos;s DNA with allele-specific oligonucleotide probes that recognize mutations, deletions, or insertions causing the disease. Also, the various infectious agents can be measured in biological fluids by hybridization with specific probes. In forensic science, hybridization of DNA with minisatellite probes allows the unique identification of individuals (DNA fingerprinting). 1,2 Radioactive probes (usually labeled with 32 P), in combination with autoradiographic detection, dominated in the field of hybridization assays for more than 2 decades and provide the highest sensitivities. However, the short half-life of 32 P, the health hazards and problems associated with its use and disposal, and the long exposure times (many hours to days) required for detection have placed limitations on the routine use of hybridization assays in the clinical laboratory. The current trend in this area is toward novel nonradioactive alternatives. 2,3 The labels can be incorporated into the probes either enzymatically (e.g., using DNA polymerase or deoxynucleotidyl transferase and modified deoxynucleoside triphosphates) or by chemical conjugation (e.g., introduction of NH 2 groups into the probe via cytidine transamination and then conjugation to the reporter molecule). 4 Nonisotopic hybridization assays based on fluorescent, chemiluminescent, or enzyme labels have been developed. Generally, there are two strategies for the analysis of hybrids. Either the reporter molecule is directly conjugated to the probe, 5,6 or a ligand is attached to the probe and the hybrids are measured in a subsequent step by adding a specific, labeled binding protein. The ligand may be biotin or a hapten (e.g., digoxigenin). Labeled (strept)avidin or antihapten antibodies may then be employed for detection. 7,8 Enzymes (such as alkaline phosphatase and horseradish peroxidase) are the most widely used nonradioisotopic labels because they provide amplification through the high turnover of their substrates to detectable products. 2 Recently, we reported 9 that a DNA fragment (DNA template) coding for an enzyme can be used as a novel label for the development of highly sensitive immunoassays (expression immunoassays). In these assays, after completion of the immunoreaction, the DNA template (a luciferase-coding DNA) is expressed by in vitro transcription/translation and the activity of the synthesized enzyme is measured. Furthermore, it was estimated that 12-14 luciferase molecules were synthesized from each DNA template molecule. In the present work, we extend our investigation in the area of hybridization assays. EXPERIMENTAL SECTION Instrumentation. Luminescence measurements were carried out using a liquid scintillation counter (Model LS-6500, Beckman Instruments Inc., Fullerton, CA) in the single photon monitoring mode. Fluorescence measurements were performed with th

The Values of Tangible User Interfaces: How to discover, assess and evaluate them?

Since the introduction of Tangible User Interfaces, in the beginning of the 90s, a generation grew up interacting with computers. At the same time the context of computing changed dramatically: from a device used almost exclusively by specialists, it evolved to a general device that plays a dominant role in our societies. But where does this leave TUI? In many respects, the idea of tangibility plays a marginal role in Human Computer Interaction. It makes sense to re-evaluate the intrinsic values of TUI design. This paper proposes to research the appropriate metrics to do so

Nonlinear Network Dynamics on Earthquake Fault Systems

Earthquake faults occur in networks that have dynamical modes not displayed by single isolated faults. Using simulations of the network of strike-slip faults in southern California, we find that the physics depends critically on both the interactions among the faults, which are determined by the geometry of the fault network, as well as on the stress dissipation properties of the nonlinear frictional physics, similar to the dynamics of integrate-and-fire neural networks.Comment: 12 pages, 4 figure