A novel approach towards usability studies for visual search tasks in graphical user interface applications using the activity theory approach

The field of Human Computer Interaction still strives for a generalized model of visual search tasks (icon search, menu search, text search, label search, search through hypertext and feature recognition). The existing models of visual search, in spite of being impressive, are limited under certain perspectives due to lack of generality. The thesis tries to provide a holistic approach for the modeling of visual search tasks in graphical user interfaces from the Activity Theory (AT) perspective with the aim of rendering a theoretical bridge between HCI and Psychology. A detailed review of literature from the variegated discipline contributing to the study of Visual Search revealed the presence of gray areas, which can be partially addressed by the Activity Theory approach. The case study uses thinking aloud Protocol Analysis technique for analyzing the complex interaction of behavior, cognition and motor action, which manifest in these tasks. The results have been analyzed and possible modifications have been identified. Interestingly, it is observed that Activity Theory can provide substantial theoretical support to aid Usability Testing Techniques

Investigating graphical user interface usability on task sequence and display structure dependencies

Designing Graphical User Interfaces (GUI) requires the consideration of task sequence requirements (sequence of operations arising from task structures and application constraints) and display structure (layout of the elements of the interface) relationships. The basic purpose was to understand the usability differences of the interfaces through efficiency, motor performance, and search performance. Thirty-two subjects performed experiments in four groups. The experiments differed in display structure and compatibility of task sequences. Subject mouse actions, mouse coordinates and eye positions were recorded. The derived measures, click efficiency, mouse traversal and eye visits to different areas of interest (namely the tool, object, and goal), were analyzed in a repeated measures factorial design with compatibility and display structure as the between subjects factors and phase of learning as the within subject factor. A significant interaction between compatibility and phase of learning (p\u3c.01) was observed. Mouse traversal per unit time increased significantly (p\u3c. 05) across phases of learning. The phase of learning affected the number of eye visits for all groups. Compatibility had a significant ((p\u3c.005) effect on the average processing time during search. The results establish that the compatibility of task sequence requirement with the display structure affecting the performance of subjects and hence the usability of the interface was thus obtained. However, through learning, subject performance showed considerable improvement and the effects of task sequence and display structure diminished at final stages of user learning. Based on this evidence, a systemic structural activity approach was used to develop a model of human performance on the eye movement and mouse action data. This structural model of human performance is defined as an algorithm and can be used for estimating complexity of task performance. In this study only the assumptions for development of the model and the formulation of the model are explained as an application of the results of the study. The study hence served a dual purpose in the long run: understanding the compatibility of the task sequence with the interface display structure as well as establishing eye and mouse movements as a viable tool to study task performance at human computer interfaces

Feasibility of Evaluating Design Ideas for Reducing Vehicular Entrapment at Railroad Crossings Using a Laboratory Experiment

The number of accidents at railroad crossings is particularly high at places where streets run parallel to the railroad tracks. Existing grade crossings were investigated for potential problems and studied for design solutions. The present study reports progress of the first phase of a NJ DOT sponsored project. A laboratory experiment was designed for evaluating various design ideas before they are implemented in the second phase field study. The laboratory study used images taken from actual scenes of railroad crossings in New Jersey, instead of graphical drawings commonly used in driving simulations. Possible design ideas were edited using image processing software. Those design ideas were saved in different layers for generating design combinations which were superimposed on the background images to create virtual railroad crossing scenes. Nighttime images were also made possible by retouching the digital daytime images. Preliminary results of the in-lab experiment were presented. The experience learned from the current project indicates that use of actual images with superimposed design ideas is a cost-effective approach of evaluating and redesigning display layout

Screening of Aeromonads as associated pathogens from Non-Tuberculous Mycobacterial infections in the aquaculture industry, West Bengal, India

The disease termed as ‘Ulcerative disease’ or ‘Erythematous disease’ is found in fishes and fish handlers and is caused by a group of waterborne Mycobacterium spp. called non-tuberculous mycobacteria (NTM). The wounds are frequently invaded by secondary pathogens like Aeromonas spp. which is ubiquitous in nature. NTMs are free-living bacterium inhabiting water bodies, causing skin lesions in fish and fish handlers. The secondary invaders are natural inhabitants and are found in excess due to anthropogenic pollution in aquatic environments affecting the fishes and human subjects as low-level latent infectants in wounds caused by NTM. This study highlights the various aspects mycobacteriosis followed by secondary infection and hemorrhagic septicemia caused by Aeromonas spp. in the state of West Bengal (WB), India. NTM and Aeromonas spp. samples were examined from different districts of WB. In the case of Fish handlers, NTM infection as well as Aeromonas spp. infected wounds were highly significant (correlation coefficient (ρ) 0.859, p<0.01). Ulcerative fishes predominant with NTMs were significantly higher in the total samples studied (correlation coefficient 0.718, p<0.01) than the fishes infected with both Aeromonas spp. and NTM (ρ 0.188, p< 0.5). Systematic reporting of mycobacteriosis and associated pathogens studied here will help to improvise the drug regimes used in culture-based fisheries systems

Microwave heating in multiphase systems: evaluation of series solutions

The 1D electric field and heat-conduction equations are solved for a slab where the dielectric properties vary spatially in the sample. Series solutions to the electric field are obtained for systems where the spatial variation in the dielectric properties can be expressed as polynomials. The series solution is used to obtain electric-field distributions for a binary oil-water system where the dielectric properties are assumed to vary linearly within the sample. Using the finite-element method temperature distributions are computed in a three-phase oil, water and rock system where the dielectric properties vary due to the changing oil saturation in the rock. Temperature distributions predicted using a linear variation in the dielectric properties are compared with those obtained using the exact nonlinear variation

Application Of Systemic-Structural Theory Of Activity In The Development Of Predictive Models Of User Performance

This article introduces the systemic-structural activity (SSA) approach to modeling user performance on human-computer interaction tasks. The human operator\u27s eye and computer mouse movements were analyzed, and their interrelationship was investigated in the framework of the SSA theory. A new method of eye movement interpretation is presented. Procedures for development of predictive design models of human performance are also suggested. These design models can be developed based on either purely analytical procedures or a combination of analytical procedures and abbreviated experimental studies. Developed models are task specific and are described in terms of human actions and operations, rather than in terms of the internal cognitive architecture. The design process is considered in terms of stages of the sequential refinement of designed models