Evaluation of complex and dynamic safety tasks in human learning using the ACT-R and SOAR skill acquisition theories

This paper provides a human-centered analytical approach to learning dynamic and complex tasks using the Adaptive Control of Thought-Rational (ACT-R) and the State, Operator And Result (SOAR) models by comparing the task times of the model and the subjects. Twenty-one full time assembly line workers at a local computer company (14 men and 7 women) from ages 18-32 (Mean = 19.86 years, SD = 0.96 years) were randomly selected for this analysis. The task involved the placement of printed circuit board (PCB) components on the flow line of the desktop computer mother board manufacturing process. The overall timed performance of the subjects indicated that the match between the model and the subjects was good, resulting in an R² - value of 0.94. At the unit task level performance, and R² - value of 0.96 for placing the PCBs on the flow line. For tasks involving picking and searching of PCBs, the obtained R² - value was 0.76 and R² of 0.68 at the keystroke level. Findings revealed that the model already started out with a complete strategy of performing the task, whereas the human participants had to acquire additional learning information during the trials. Efforts will be made in the future to determine how the performance of the human subjects could be enhanced to meet or the same level as the model performance.     

Comparison of 3D and 2D menus for cell phones

Few prior studies have directly compared 3D and 2D menus for cell phones. Because the technology available for cell phone interfaces has changed in recent years, interface guidelines for cell phones need to be re-evaluated, especially with regard to the use of 3D interfaces. In the present study, we first compared performance of tasks for menus with different breadths using three 3D menus (revolving stage, 3D carousel, and collapsible cylindrical tree) shown on the small display screen of an iPhone® simulator. Performance was best with the revolving stage menu, and there was a nonsignificant tendency for it to be rated as preferred by the participants. Then, we compared the 3D revolving stage menu to a 2D overview menu, for tasks of different complexity and menus of different breadths, on an actual iPhone. The 3D menu was preferred by users at high breadth levels, and the 2D menu showed better performance than the 3D menu with low memory load. From the results, recommendations for the design of menus for small displays were developed.     

Pull-down versus traditional menu types: an empirical comparison

An experiment was conducted to test the performance of pull-down versus traditional or explicit menus. Sixty subjects, including novice and experienced computer users, manipulated both types of menus to complete banking tasks similar to those found on Automatic Teller M achines. The order of the menus was randomly varied to control for learning effects. Across both types of users, traditional-style menus elicited fewer errors than did pull-down menus; however, no significant difference was found in the time to complete the banking task. Experienced users outperformed novice users in the amount of time taken to complete the task regardless of menu type, though no difference was found in the number of errors committed by both user types.     

Pull-down versus traditional menu types: An empirical comparison

An experiment was conducted to test the performance of pull-down versus traditional or explicit menus. Sixty subjects, including novice and experienced computer users, manipulated both types of menus to complete banking tasks similar to those found on Automatic Teller M achines. The order of the menus was randomly varied to control for learning effects. Across both types of users, traditional-style menus elicited fewer errors than did pull-down menus; however, no significant difference was found in the time to complete the banking task. Experienced users outperformed novice users in the amount of time taken to complete the task regardless of menu type, though no difference was found in the number of errors committed by both user types.     

Changes in the amount and structure of motor variability during a deboning process are associated with work experience and neck-shoulder discomfort

In this field study, the size and structure of kinematics variability were assessed in relation to experience and discomfort during a deboning task. Eighteen workers divided in groups with low/high experience and with/without neck-shoulder discomfort participated. Standard deviation and coefficient of variation (amount of variability), as well as approximate entropy and sample entropy (complexity) and, correlation dimension (dimensionality) were computed for head-shoulder, shoulder-hip and elbow-hip displacement in the vertical direction. A longer work experience was associated with shorter work cycle duration and decreased amount of variability while complexity increased for the head-shoulder displacement, P < 0.05. Shorter work cycle, lower amount of variability and, lower dimensionality for the head-shoulder displacement were found in relation to discomfort, P < 0.05. While the amount of variability, complexity and dimensionality increased for the elbow-hip displacement, P < 0.05. These findings suggest a functional role of experience via learning effects and discomfort through compensatory mechanisms on the size and structure of motor variability.     

Relationships between maximum holding time and ratings of pain and exertion differ for static and dynamic tasks

Ratings of perceived discomfort (0 to 10 scale) have been used to estimate relative maximum holding times (%MHT), particularly for static tasks. A linear 1:10% ratio has been described, where a rating of 5 corresponds to 50%MHT. It is unknown whether this linear ratio is valid for dynamic tasks. Additionally, whether pain or exertion are the primary predictors of discomfort is not clear. Thus, the goal of this study was to investigate both pain and exertion ratings during static (50% maximum; N = 42) and dynamic (75% maximum; N = 34) elbow flexion tasks until failure. Gender, self-reported physical activity, and peak torque were also assessed. Pain and exertion ratings reasonably matched the 1:10% ratio during the static task but not during the dynamic task. Exertion related more strongly to MHT than pain in both tasks. Neither gender nor activity level appeared to influence perceptual ratings, but peak torque explained approximately 20% of the variance in MHT.     

Assessing Web interaction with recollection: Age-related and task-related differences

The current study examined how young (n = 26; mean = 22.31 years) and older Internet users (n = 24; mean = 64.54 years) performed when they had to select and recollect information displayed in Web pages. Content-oriented and navigation-oriented information-finding tasks were used during the study phase. At test, the method made use of two recognition paradigms designed to assess recollection and the nature of representations in memory: namely, the remember/know procedure and a forced-choice recognition procedure which made it possible to compare the retrieval of detailed (verbatim-based) and semantic (gist-based) representations. The evidence from both procedures suggested that remembering was less contextualised in older participants. Furthermore, the idea that content-oriented searches impose greater processing demands than navigation-oriented searches in Web pages was confirmed for both age groups. Interestingly, the older Internet users experienced more difficulties in finding targets in navigation-oriented searches than in content-oriented searches.     

Beyond the fascination of online-games: Probing addictive behavior and depression in the world of online-gaming

This study examined problematic gaming behavior and depressive tendencies among people who play different types of online-games. Other game-related variables were investigated to determine if other differences between three game types could be established. Participants in the current research (n = 468) can be classified into three independent groups. Subjected users either solely played massive multiplayer online role-playing games (MMORPGs) or they preferred online-ego-shooters (OES) or real-time-strategy games (RTS). Results indicate that MMORPG users show more often problematic gaming behavior, depressive tendencies and lower self-esteem compared to users playing other online-games. MMORPG users reported to playing significantly more often in order to escape from real-life problems, which might be a valuable coping strategy but might also lead to problematic gaming behavior.     

Micro tracking and positioning using off-the-shelf servopneumatics

Conventional pneumatic systems do not exhibit significant heat or magnetic fields and present high force to volume ratios. They are, however, typically confined to simple motion tasks owing to their control complexity. Leveraging on a sliding mode based control strategy, the authors have shown in previous works that good tracking and positioning results can be achieved using off-the-shelf servopneumatics. This paper extends the previously mentioned works by applying a modified version of the control law to a new experimental setup comprising different valves and actuators and a better resolution encoder. The modification of the control law involves the use of a new boundary layer thickness variation law, different from the one previously used. Experimental results show that the modified control law leads to very accurate motion control. The positioning error from a control perspective is only limited by the encoder resolution, 1 μm, in any position of the piston stroke and when carrying loads of 3 kg and 8 kg, without any controller retuning. Good results in the micrometer range are also obtained when tracking sinusoidal and triangular references.     

Finding Information on a Menu: Linking Menu Organization to the User's Goals

Design paradigms often ignore the diverse goals users bring to the computer interface. Any human-computer interaction can be viewed as a marriage of two systems: The user begins the interaction by formulating an information goal, and the computer software meets that goal with a sometimes complex list of potential topic areas. The user then accesses that topic list through the computer interface. Part of the act of accessing the topic list is selecting a potential topic, and this action is often supported by a menu interface. Although research is pervasive on how best to organize menu items to facilitate learning, search speed, and reduced selection errors, little has been done to examine the impact of different types of user goals or cues on a menu's effectiveness. In a study using three distinct cues-direct match, synonym, and iconic - and two menu organizations - alphabetical and functional-data suggest that (a) the functional menu is more effective than the alphabetical menu for the synonym and iconic cues, (b) learning occurs with both menu designs (i.e., selection speed increases rapidly across the five trial blocks), and (c) users make fewer errors with the functionally organized menu. The results, in general, encourage more rigorous investigation of the interaction between the tasks users bring to menu interfaces and the optimal design of those menus.     

Book Review

In this experiment, older and younger novice mobile phone users were examined when using handsets of different complexity. The independent variables were user age (young: 20 – 35 years; old: 50 – 64 years) and cognitive complexity of two mobile phones (Nokia 3210; Siemens C35i). The cognitive complexity of the phones was defined by the number of production rules applied when processing the four experimental tasks. Dependent variables were effectiveness and efficiency as taken from user protocols and the reported ease of use. The less complex phone (Nokia) performed significantly better than the complex one (Siemens). However, the benefit from the lower complexity was much larger than theoretically predicted. Thus, defining cognitive complexity of technical devices by the number of production rules does not account for the real difficulties which users experience. Older users had a lower navigation performance than younger users, however their performance matched younger users' when using mobiles with low complexity.     

Visualizing references to off-screen content on mobile devices: A comparison of Arrows, Wedge, and Overview + Detail

When navigating large information spaces on mobile devices, the small size of the display often causes relevant content to shift off-screen, greatly increasing the difficulty of spatial tasks such as planning routes or finding points of interest on a map. Two possible approaches to mitigate the problem are Contextual Cues, i.e. visualizing abstract shapes in the border region of the view area to function as visual references to off-screen objects of interest, and Overview + Detail, i.e., simultaneously displaying a detail view and a small-scale overview of the information space. In this paper, we compare the effectiveness of two different Contextual Cues techniques, Wedge (Gustafson et al., 2008) and Scaled Arrows (Burigat et al., 2006), and a classical Overview + Detail visualization that highlights the location of objects of interest in the overview. The study involved different spatial tasks and investigated the scalability of the considered visualizations, testing them with two different numbers of off-screen objects. Results were multifaceted. With simple spatial tasks, no differences emerged among the visualizations. With more complex spatial tasks, Wedge had advantages when the task required to order off-screen objects with respect to their distance from the display window, while Overview + Detail was the best solution when users needed to find those off-screen objects that were closest to each other. Finally, we found that even a small increase in the number of off-screen objects negatively affected user performance in terms of accuracy, especially in the case of Scaled Arrows, while it had a negligible effect in terms of task completion times.     

Assessing the usability of icons in user interfaces

Abstract

This paper presents a methodology and results of an experiment to assess the usability of menu items constructed of text, icons, and text-and-icons. Attributes of menu items are used to form a matrix which can be used to classify menu items for use in certain applications, tasks, or with users of particular experience levels. An experiment was conducted to validate a portion of the attribute matrix. Performance measures were accuracy of selection and time to make a selection. Results suggest that menus constructed of a mixed format (text and icons) result in the fewest number of incorrect selections by users. No significant differences in the time to make a selection were found.     

Complementary menus: Combining adaptable and adaptive approaches for menu interface

This study proposes a method of coupling adaptable and adaptive approaches to the design of menus. The proposed complementary menu types incorporate both adaptability and adaptivity by dividing and allocating menu adaptation roles to the user and the system. Four different types of interface adaptation (i.e., adaptable with/without system support and adaptive with/without user control) were defined. They were implemented in a hypothetical prototype mobile phone via a hotlist (an additional collection of quickly accessible items). A controlled lab experiment was conducted to compare the menu types and investigate the effects of the system support in the adaptable menus and the user control in the adaptive menus. Twenty subjects participated in the experiment and performed menu selection tasks. Both performance and user satisfaction measures were collected. The results showed that adaptable and adaptive menus were superior to the traditional one in terms of both performance and user satisfaction. Providing system support to the adaptable menu not only increased the users’ perception of the efficiency of selection, but also reduced the menu adaptation time. Important implications for the design of menus are described and valuable insights into the menu interface adaptation were gained from the quantitative and qualitative analyses of the experimental results.

Relevance to industry

The evaluation experiment conducted in this study may provide valuable information to designers of adaptive or adaptable menus. Adding system support to adaptable menu would be an attractive option to consider. Also, the results of a user survey provide useful information to the practitioners in mobile phone industry on the features users accessed most frequently.     

A Predictive Model of Human Performance With Scrolling and Hierarchical Lists

ABSTRACT

Many interactive tasks in graphical user interfaces involve finding an item in a list but with the item not currently in sight. The two main ways of bringing the item into view are scrolling of one-dimensional lists and expansion of a level in a hierarchical list. Examples include selecting items in hierarchical menus and navigating through “tree” browsers to find files, folders, commands, or e-mail messages. System designers are often responsible for the structure and layout of these components, yet prior research provides conflicting results on how different structures and layouts affect user performance. For example, empirical research disagrees on whether the time to acquire targets in a scrolling list increases linearly or logarithmically with the length of the list; similarly, experiments have produced conflicting results for the comparative efficacy of “broad and shallow” versus “narrow and deep” hierarchical structures. In this article we continue in the human–computer interaction tradition of bringing theory to the debate, demonstrating that prior results regarding scrolling and hierarchical navigation are theoretically predictable and that the divergent results can be explained by the impact of the dataset's organization and the user's familiarity with the dataset. We argue and demonstrate that when users can anticipate the location of items in the list, the time to acquire them is best modeled by functions that are logarithmic with list length and that linear models arise when anticipation cannot be used. We then propose a formal model of item selection from hierarchical lists, which we validate by comparing its predictions with empirical data from prior studies and from our own. The model also accounts for the transition from novice to expert behavior with different datasets.     

An agglomerative clustering algorithm using a dynamic k-nearest-neighbor list

In this paper, a new algorithm is developed to reduce the computational complexity of Ward’s method. The proposed approach uses a dynamic k-nearest-neighbor list to avoid the determination of a cluster’s nearest neighbor at some steps of the cluster merge. Double linked algorithm (DLA) can significantly reduce the computing time of the fast pairwise nearest neighbor (FPNN) algorithm by obtaining an approximate solution of hierarchical agglomerative clustering. In this paper, we propose a method to resolve the problem of a non-optimal solution for DLA while keeping the corresponding advantage of low computational complexity. The computational complexity of the proposed method DKNNA + FS (dynamic k-nearest-neighbor algorithm with a fast search) in terms of the number of distance calculations is O(N²), where N is the number of data points. Compared to FPNN with a fast search (FPNN + FS), the proposed method using the same fast search algorithm (DKNNA + FS) can reduce the computing time by a factor of 1.90-2.18 for the data set from a real image. In comparison with FPNN + FS, DKNNA + FS can reduce the computing time by a factor of 1.92-2.02 using the data set generated from three images. Compared to DLA with a fast search (DLA + FS), DKNNA + FS can decrease the average mean square error by 1.26% for the same data set.     

Adapting menu layout to tasks

Menus are an increasingly popular style of user-system interface. Although many aspects of menu design can affect user performance (e.g. item names and selection methods), the organization of items in menus is a particularly salient aspect of their design. Unfortunately, empirical studies of menu layout have yet to resolve the basic question of how menus should be organized to produce optimal performance. Furthermore, a disturbingly common finding has been that any initial effects of menu layout disappear with practice. Thus it is tempting to conclude that menu organization is not important or that it only affects performance during learning. In this paper we present some reasons to doubt this conclusion. In particular, we have found persistent effects of layout with multiple-item selection tasks, in contrast with studies employing a single-item selection paradigm. The results of a controlled study comparing various menu designs (fast-food keyboards) show that the types of tasks to be performed by users must be considered in organizing items in menus and that there may be sustained effects of menu organization with some tasks. In addition, the results of this study support the use of a formal methodology based on user knowledge for menu design. By comparing the performance of subjects using menus designed using our methodology with the performance of subjects using “personalized” menus, we were able to demonstrate the general superiority of our method for designing menus, and for tailoring menus to meet task requirements as well.     

Task and user effects on reading patterns in information search

We report on an investigation into people’s behaviors on information search tasks, specifically the relation between eye movement patterns and task characteristics. We conducted two independent user studies (n = 32 and n = 40), one with journalism tasks and the other with genomics tasks. The tasks were constructed to represent information needs of these two different users groups and to vary in several dimensions according to a task classification scheme. For each participant we classified eye gaze data to construct models of their reading patterns. The reading models were analyzed with respect to the effect of task types and Web page types on reading eye movement patterns. We report on relationships between tasks and individual reading behaviors at the task and page level. Specifically we show that transitions between scanning and reading behavior in eye movement patterns and the amount of text processed may be an implicit indicator of the current task type facets. This may be useful in building user and task models that can be useful in personalization of information systems and so address design demands driven by increasingly complex user actions with information systems. One of the contributions of this research is a new methodology to model information search behavior and investigate information acquisition and cognitive processing in interactive information tasks.     

The design and analysis of an efficient load balancing algorithm employing the symmetric balanced incomplete block design

In order to maintain load balancing in a distributed network, each node should obtain workload information from all the nodes in the network. To accomplish this, this processing requires O(v²) communication complexity, where v is the number of nodes. First, we present a new synchronous dynamic distributed load balancing algorithm on a (v, k + 1, 1)-configured network applying a symmetric balanced incomplete block design, where v = k² + k + 1. Our algorithm designs a special adjacency matrix and then transforms it to (v, k + 1, 1)-configured network for an efficient communication. It requires only communication complexity and each node receives workload information from all the nodes without redundancy since each link has the same amount of traffic for transferring workload information. Later, this algorithm is revised for distributed networks and is analyzed in terms of efficiency of load balancing.