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Browsing by Author "Green, Charles A."

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    Development and validation of a methodology for comprehensive performance assessment of complex tasks
    Green, Charles A. (Virginia Tech, 1995-04-15)
    A new task analysis methodology was developed to provide objective information on complex tasks. A complex task was broken down into observable elements and unobservable elements that were inferred to have taken place in support of the observable actions. Subject matter experts (SMEs) were used to assist in this breakdown. Additionally, guidelines for specifying the level of detail in the task analysis breakdown were developed to help objectify the analysis. A simulation model framework then was built of the task elements. Personnel proficient in the task were observed during work, and objective data on their observable actions were collected. These data then were used to provide numeric input to a simulation model. The simulation was run, and the results of the model of performance compared to the observed performance data. The model was altered at that point to reflect lessons learned during data collection. The process yielded a model that accurately reflects human performance on the task. Variations on the model based on a conceptual understanding of operators strategies also correlated well with observed performance, indicating the value of the methodology for building an understanding of the motivations critical to successful task performance.
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    An empirical study on the effects of a collaboration-aware computer system and several communication media alternatives on product quality and time to complete in a co-authoring environment
    Green, Charles A. (Virginia Tech, 1992-08-15)
    A new type of software, termed a "group editor", allows multiple users to create and simultaneously edit a single document; this software has ostensibly been developed to increase efficiency in co-authoring environments where users may not be co-located. However, questions as to the effectiveness of this type of communication aid, which is a member of the "groupware" family of tools used for some types of computer supported cooperative work, remain. Particularly, there has been very little objective data on any group editor because of the problems inherent in evaluating writing, as well as due to the few examples of group editors that exist. A method was developed to examine the effect of using a particular group editor, Aspects™ from Group Technologies in Arlington, Va., in conjunction with several communication media, on a simple dyad writing task. Six dyads of college students familiar with journalistic writing were matched on attributes of dominance and writing ability and were asked to write short news articles based on short video clips in a balanced two factor within-subject analysis of variance design. Six conditions were tested based on communication media: audio only, audio plus video, and face-to-face; each of these with and without the availability of the group editor. Constraints inherent in the task attempted to enforce consistent document quality levels, measured by grammatical quality and content quality (correctness of information and chronological sequencing). Time to complete the articles was used as a measure of efficiency, independent from quality due to the consistent quality levels of the resulting work. Results from the time data indicated a significant effect of communication media, with the face-to-face conditions taking significantly less time to complete than either of the other media alternatives. Grammatical quality of the written articles was found to be of consistent high quality by way of computerized grammar checker. Content quality of the documents did not significantly differ for any of the conditions. A supplemental Latin square analysis showed additional significant differences in time to complete for trial means (a practice effect) and team differences. Further, significantly less variance was found in certain conditions which had the group editor than in other conditions which did not. Subjective data obtained from questionnaires supported these results and additional1y showed that subjects significantly preferred trials with the group editor and considered then more productive. The face-to-face conditions may have been more efficient due to the nature of the task or due to increased communication structure within dyads due to practice with the group editor. The significant effect of Team Differences may have been due to consistent style differences between dyads that affected efficiency levels. The decreased variability in time to complete in certain group editor conditions may have been due to increased communication structure in these conditions, or perhaps due to leveling effects of group writing as opposed to individual writing with team member aid. These hypotheses need to be tested with further study, and generalizability of the experimental task conditions and results from this particular group editor need to be established as well face-to-face conditions clearly resulted in the most efficient performance on this task. The results obtained concerning the group editor suggest possible efficiency or consistency benefits from the use of group editors by co-authoring persons when face-to-face communication is not practical. Perhaps group editors will become a useful method for surrogate travel for persons with disabilities.
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    The "Out-of-the-Loop" concept in automated driving: proposed definition, measures and implications
    Merat, Natasha; Seppelt, Bobbie; Louw, Tyron; Engström, Johan; Lee, John D.; Johansson, Emma; Green, Charles A.; Katazaki, Satoshi; Monk, Chris; Itoh, Makoto; McGehee, Daniel V.; Sunda, Takashi; Unoura, Kiyozumi; Victor, Trent; Schieben, Anna; Keinath, Andreas (Springer, 2019-02)
    Despite an abundant use of the term Out of the loop (OOTL) in the context of automated driving and human factors research, there is currently a lack of consensus on its precise definition, how it can be measured, and the practical implications of being in or out of the loop during automated driving. The main objective of this paper is to consider the above issues, with the goal of achieving a shared understanding of the OOTL concept between academics and practitioners. To this end, the paper reviews existing definitions of OOTL and outlines a set of concepts, which, based on the human factors and driver behaviour literature, could serve as the basis for a commonly-agreed definition. Following a series of working group meetings between representatives from academia, research institutions and industrial partners across Europe, North America, and Japan, we suggest a precise definition of being in, out, and on the loop in the driving context. These definitions are linked directly to whether or not the driver is in physical control of the vehicle, and also the degree of situation monitoring required and afforded by the driver. A consideration of how this definition can be operationalized and measured in empirical studies is then provided, and the paper concludes with a short overview of the implications of this definition for the development of automated driving functions.