This study examined the often contrived advertising claims of the manufacturers of variable resistance isotonic machinery. Specifically, the study sought to ascertain whether certain equipment was compatible with musculo-skeletal and perceptual needs and limitations of the human user: that is, to determine whether presently installed eccentric cams, which provide the variable resistance, matched the users force curves. The format of this research was in the ergonomic tradition in which empirical research is not necessarily the primary avenue. Consequently the inter-disciplinary nature of ergonomics required small-scale laboratory- simulation experiments to be conducted in a diverse range of disciplines such as physiology, psychology and biomechanics. It was found that on all five pieces of variable resistance machinery analysed, a mismatch between the force curves and the eccentric cams exist. The cams were redesigned accordingly. The metabolic cost of performing fixed-rate isoinertial lifts was moderate. The psychophysical analysis revealed that perceptual responses indicated that the work was classified as 'light' and only at 30% stress levels do local cues begin to dominate. Based on these findings it was concluded that manufacturers advertising claims in the instances analysed were not well-founded and that variable resistance isotonic machinery should only be used to develop muscular strength and endurance, and do not effectively serve as weight-loss devices.

La conception d’interface écologique se décompose en deux étapes, une analyse du domaine de travail et une retranscription des informations du domaine en des représentations écologiques (Naikar, 2010). Ce type de conception a montré son efficacité pour la supervision de système complexe (Burns, 2008). Cependant, Vicente (2002) a pointé deux lacunes le temps de conceptions très long et la difficulté à transcrire de manière formalisée un domaine de travail en des représentations écologiques. De même, il n’existe pas d’outil formel de validation de domaine de travail. Dans ce manuscrit, nous proposons plusieurs réponses à la question : comment formaliser la conception d’une interface écologique, afin de réduire le temps et les efforts liés à la conception ? La première proposition est un outil de vérification de modèle de domaine de travail basé sur la méthode TMTA (Morineau, 2010). La seconde apporte, au travers d’une deuxième version du flot Anaxagore (Bignon, 2012), une intégration des travaux de Liu et al (2002) avec le principe d’une bibliothèque de widgets écologiques associée à un schéma d’entrées de haut niveau. Sur la base du domaine de travail d’un système d’eau douce sanitaire à bord d’un navire, une interface écologique a été implémentée et validée expérimentalement. Cette interface a été comparée à une interface conventionnelle générée également par le flot Anaxagore. Les résultats montrent que les interfaces écologiques favorisent un plus grand nombre de parcours cohérents dans un domaine de travail. Elles favorisent également une meilleure précision du diagnostic pour les opérateurs utilisant les interfaces écologiques. / The ecological interface design is composed of two steps, a work domain analysis and a transcription of the information of the work domain into ecological representation (Naikar, 2010). This kind of design showed his effectiveness for the supervision of complex system (Burns, 2008). Nevertheless, Vicente (2002) highlighted two issues, the long design time and the difficulties to translate with a formal way a work domain into ecological representation. Moreover, he doesn’t exist a formal tool of validation for a work domain. Several tools and works allow to be comfortable in the possibility to find some solution (Functional methodology (Liu et al, 2002), TMTA (Morineau, 2010) and Anaxagore (Bignon, 2012). We propose several answers at the issue: how formalize the design of an ecological interface in order to reduce the time and effort linked to the design? The first proposition is a tool of verification of model of work domain based on a simulation by TMTA. The second bring thanks to a second version of the Anaxagore flow, an integration of the works of Liu et al (2002) with the principle of the ecological library of ecological widget linked to a scheme of input of high level. Based on the work domain of a fresh water system in a ship, an ecological interface has been implemented and validated experimentally. This interface has been compared with a conventional interface also generated by Anaxagore. The results show that the ecological interface promotes a biggest numbers of coherent ways in the work domain. This kind of interface also promotes a better accuracy of the diagnostic for the operators using the ecological interface.

Despite extensive research into the concept of mental fatigue there is as yet no “gold standard” definition or measurement technique available. Because of this a large amount of fatigue-related errors are still seen in the workplace. The complexity of the problem lies with the inability to directly measure mental processes as well as the various endogenous and exogenous factors that interact to produce the experienced fatigue. Fatigue has been divided into sleep-related and task-related fatigue; however the task-related aspect is evident both during normal waking hours as well as during periods of sleep deprivation, therefore this aspect is considered important in the understanding of fatigue in general. The concept of task-related fatigue has further been divided into active and passive fatigue states; however differentiation between the two requires careful consideration. Various physiological measures have been employed in an attempt to gain a better understanding of the mechanisms involved in the generation of fatigue, however often studies have produced dissociating results. The current study considered the task-related fatigue elicited by a tracking task requiring sustained attention, in order to evaluate the usefulness of various cardiovascular and oculomotor measures as indicators of fatigue. A secondary aim was to determine whether the behavioural and physiological parameter responses could be used to infer the type of fatigue incurred (i.e. an active versus passive fatigue state) as well as the energetical mechanisms involved during task performance. A simple driving simulator task was used as the main tracking task, requiring constant attention and concentration. This task was performed for approximately two hours. Three experimental groups (consisting of 14 subjects each) were used: a control group that performed the tracking task only, a group that performed a five minute auditory memory span task concurrently with the driving task after every 20 minutes of pure driving, and a group that performed a visual choice reaction task for five minutes following every 20 minute driving period. The secondary tasks were employed in order to evaluate the extent of resource allocation as well as arousal level. Performance measures included various driving performance parameters, as well as secondary task performance. Physiological measures included heart rate frequency (HR) and various time- and frequency-domain heart rate variability (HRV)parameters, pupil dilation, blink frequency and duration, fixations, and saccadic parameters as well as critical flicker fusion frequency (CFFF). The Borg CR-10 scale was used to evaluate subjective fatigue during the task, and the NASA-TLX was completed following the task. A decline in driving performance over time was supplemented by measures such as HR, HRV and pupil dilation indicating an increase in parasympathetic activity (or a reduction in arousal). An increase in blink frequency was considered as a sign of withdrawal of attentional resources over time. Longer and faster saccades were also evident over time, coupled with shorter fixations. With regards to the secondary task influence, the choice RT task did not affect any behavioural or physiological parameters, thereby contesting the active fatigue theory of resource depletion, as well as implying that the increase in demand for the same resources used by the primary task was insufficient to affect the state of the subjects. The increased load elicited by the memory span task improved driving performance and increased measures of HR, HRV, pupil dilation and blink frequency. Some of these measures produced opposite effects to what was expected; an attempt to explain the dissociation of the various physiological parameters was expressed in terms of arousal, effort and resource theories. Overall, the results indicate that the fatigue and/or reduced arousal accompanying a monotonous sustained attention task can, to some degree, be alleviated through intermittent performance of a secondary task engaging mental resources other than the ones used for the primary task. The degree to which such a task is beneficial, however, requires careful consideration as while an immediate increase in arousal and primary task performance is noted, the impact of the task on general attentional resources may be detrimental in the case of reacting should an emergency situation occur.

Ergonomics aims to improve worker health and enhance productivity and quality. Knowledge and practical evidence of this relationship would be instrumental for optimising organisational performance particularly in industrially developing countries where the discipline is still in its developmental stages. Therefore this thesis set out to analyse the relationship between ergonomics deficiencies and performance. A survey was first conducted to establish the severity of quality problems in the South African manufacturing industry and to determine if these were related to Ergonomic deficiencies. The results indicated that quality problems continue to plague industry, a challenge associated with huge cost implications. Furthermore organisations were not cognisant of the fact that ergonomics deficiencies such as poor workstation design and awkward or constrained working postures are a major contributing factor to poor quality and performance decrements. This demonstrates that much is yet to be done in raising awareness about the benefits of ergonomics in South Africa and other industrially developing countries. However, for this to be effective, tangible evidence of these purported benefits is required. In lieu of this, a laboratory study was then conducted to establish the relationship between awkward working postures and the performance of precision tasks. Acknowledging that the task and the worker are interrelated elements, the impact of precision task demands on the postural strain experienced by the human was also investigated. A high and low precision task quantified positional precision while a force task (combination of pushing and pulling) was utilised to assess the ability to maintain a precise force over time. These three tasks were performed in eight different postures; namely seated, standing, stooping 300 and 600, working overhead, lying supine, and twisting to either side. A combination of the tasks and postures resulted in 24 experimental conditions that were tested on forty eight healthy male and female participants. The performance related dependent variables were movement time, deviation from the centre of the target, and the trend/slope followed by the force exerted. Muscle activity of eight arm, shoulder and back muscles, iii supplemented with heart rate and local ratings of perceived exertion, were utilised to quantify the impact of the tasks and the postures on the individual. The results revealed that awkward working postures do in fact influence performance outcomes. In this regard, awkward working postures (such as overhead work and lying supine and stooping) were evidenced to significantly affect movement time, deviations from the target and the ability to maintain a constant force over time. These variables have a direct relationship with organisational priorities such as productivity and quality. Furthermore, the results indicated that high precision demands augment postural strain elicited through high muscle activity responses and may have negative implications for the precipitation of musculoskeletal disorders. Essentially, the work done on this thesis reflected the complex nature of ergonomics by drawing on both macro and micro-ergonomics approaches. In so doing, challenges perceived to be relevant to industry as reported by organisations formed the foundation for further laboratory studies. Therefore, more collaborative research and knowledge transfer between industry and ergonomics researchers is a necessity particularly in industrially developing countries where ergonomics is still in its developmental stages.

The present study sought to investigate the effects of a Standard workstation, designed for “average” users, on an anthropometrically diverse sample of computer operators, and to assess whether physical and perceptual responses, as well as performance efficiency were dependent on stature. Further investigation assessed the influence of personalised adjustments to the Standard workstation, based on the anthropometric characteristics of the subjects, as well as the introduction of a custom-designed ‘floating’ wrist support, on subject responses. All subjects (n=30) were tested in each of the three workstations: Standard, Personalised and Wrist Support. For analysis of responses in the Standard workstation, subjects were divided into three groups depending on their stature: Short (<1650mm), Medium (1650mm to 1800mm), Tall (>1800mm). The musculoskeletal responses indicated that Tall subjects were forced to adopt the most awkward general body postures as a result of the low computer screen. However, the low screen allowed for the Short subjects to adopt the most natural general body postures, although levels of muscular activity in the upper trapezius suggest that the muscular load imposed on both Short and Tall subjects was significantly greater than that imposed on the Medium subjects. In addition, the Medium subjects’ perceptions of the Standard workstation dimensions support the fact that this workstation was better suited to users with “average” morphologies. The responses elicited in the Personalised and Wrist Support workstations were improved significantly when compared to the Standard workstation. Joint angles were more natural, upper trapezius EMG was reduced, standard of performance improved and perceptual responses indicated a diminished incidence of body and visual discomfort, as well as greater perceived satisfaction with these workstation dimensions. The improved physical responses suggest a decrease in the risk of developing cumulative trauma disorders. Although subjects were unaccustomed to the wrist support device, this workstation demonstrated a further reduction in the range of wrist angles, as well as a general positive attitude towards the concept.

La réussite des projets d’introduction d’innovations technico-organisationnelles au sein de systèmes complexes passe par une capacité d’anticipation des conséquences des évolutions programmées. L’ergonomie se saisit de cet enjeu en proposant des démarches méthodologiques visant à approcher l’activité future. Comment décrire, analyser, modéliser l’activité et un futur dispositif, pour les mettre en relation afin d’élaborer des visions de ce que pourrait devenir l’activité ? La question critique est celle de la projection de l’activité dans la situation régie par le futur dispositif. L’examen des démarches existantes montre que les caractéristiques des projets d’innovation et celles des situations concernées peuvent rendre ces démarches difficiles à mettre en œuvre. Une démarche alternative d’analyse prospective des innovations est proposée, qui comprend différentes étapes : caractérisation des dimensions structurantes de l’activité coopérative ; caractérisation des éléments constitutifs du futur dispositif et des grands principes sous-jacents à ces éléments ; mise en relation pour construire une vision des conséquences possibles de l’évolution du dispositif. Cette démarche a été mise à l’épreuve dans le cadre d’un projet d’évolution du dispositif de sécurisation des interventions de maintenance (consignation) dans une industrie de process à risques. Elle a permis de mettre en évidence la centralité des protocoles de coordination, qui forment un « écosystème protocolaire », et le rôle périphérique joué par certains mécanismes, tels que la production d’une conscience mutuelle (mutual awareness) / The success of the implementation of techno-organizational innovations into complex systems requires an ability to anticipate consequences of the intended evolutions. Human Factors take up this issue by putting forward methodological frameworks that aim at foreseeing future work practices. How can actual work practices and a future socio-technical environment be described, analyzed and modeled? How should these accounts be connected in order to envision future work practices? The critical issue is how to make a projection of actual work practices into the future socio-technical environment. An examination of available methodological frameworks shows that they can prove difficult to apply in cases where innovation projects, and the settings those projects deal with, present specific characteristics. An alternative framework to guide prospective analysis of innovations is proposed. Its different stages are: (i) characterizing the structuring dimensions of cooperative work; (ii) characterizing features of the future socio-technical environment and major assumptions underlying those features; (iii) making the connection in order to envision possible consequences of the environment evolutions. This methodological framework was tested in the context of a project that aims at improving the maintenance staff protection (tagout) socio-technical environment in a high-risk process industry. It enabled to highlight the importance of coordinative protocols, which shape an “ecosystem of protocols”, and the peripheral role of some other mechanisms, such as the production of mutual awareness

Les Technologies de l’Information en Santé (TIS) sont de plus en plus utilisées pour améliorer la qualité des soins et la sécurité du patient. Cependant, certains problèmes d’utilisabilité peuvent amenuiser leur impact et peuvent même induire de nouveaux problèmes dont la mise en danger du patient. Pour éviter ces effets négatifs, il est notamment nécessaire d’améliorer l’utilisabilité des TIS ce qui requiert l’application de connaissances d’utilisabilité éprouvées. Les connaissances en utilisabilité appliquée aux TIS sont rares, éparpillées à travers diverses supports et peu utilisables. Par ailleurs, leur couverture en termes de problèmes d’utilisabilité est peu connue. Ce travail a deux objectifs: (i) participer à l’amélioration de l’accumulation de la connaissance en utilisabilité pour les TIS, (ii) fournir une connaissance structurée sur l’utilisabilité des TIS et dont la couverture est établie. Le domaine d’application est celui des systèmes d’alerte médicamenteux.Méthode. Deux analyses indépendantes de la littérature ont été menées : d’un côté, identifier et organiser les problèmes d’utilisabilité des systèmes d’alerte médicamenteux ainsi que leurs conséquences ; de l’autre, identifier et synthétiser les principes d’utilisabilité spécifiques à ces systèmes. Les résultats de ces analyses ont été croisés afin de connaitre la couverture desdits principes en termes de problèmes d’utilisabilité.Résultats. La revue systématique a identifié 13 types de problèmes d’utilisabilité dans les systèmes d’alerte médicamenteux. Les conséquences de ces problèmes sur le clinicien et son système de travail sont variées et ont un grand pouvoir de nuisance (e.g., fatigue, erreur d’interprétation). Au total, 63 principes d’utilisabilité permettent de rendre compte de tous les problèmes d’utilisabilité identifiés. Ils sont organisés en 6 thèmes : améliorer le ratio signal-bruit, être en adéquation avec l’activité des cliniciens, supporter le travail collaboratif, afficher les informations pertinentes, rendre le système transparent et fournir des outils utiles. Le croisement des deux ensembles de données révèle une bonne correspondance entre les principes d’utilisabilité énoncés et les problèmes d’utilisabilité réellement observés.Discussion. Une liste structurée des principes d’utilisabilité illustrés par des exemples réels de leur violation a été développée à partir de ce travail. Cette liste peut aider les concepteurs et les experts en Facteurs Humains à comprendre et à appliquer les principes d’utilisabilité durant la conception et l’évaluation de systèmes d’alerte médicamenteux. L’utilisabilité appliquée aux TIS est une discipline relativement récente qui souffre d’un déficit de structuration et de capitalisation de ses connaissances. Ce travail montre qu’il est possible d’accumuler et de structurer les données d’utilisabilité des TIS. Ce travail pourrait être poursuivi en développant une base de connaissance en utilisabilité appliquée aux TIS afin de tendre vers une « utilisabilité fondée sur les preuves ». / Health Information Technology (HIT) is increasingly implemented to improve healthcare quality and patient safety. However, some usability issues may reduce their impact and even induce new problems (including patient safety issues). To avoid those negative outcomes, amongst other actions, HIT usability must be improved. This action requires applying validated usability knowledge. However, usability knowledge applied to HIT is scattered across several sources, is not structured and is hardly usable. Moreover, its coverage regarding related usability flaws is not known. This work has two aims: (i) to participate in improving the accumulation of usability knowledge for HIT and (ii) to provide synthetic structured easy-to-use HIT usability knowledge with a clear coverage. Those aims are applied to medication alerting systems.Method.Two independent analyses of the literature have been performed. On the one hand, usability flaws and their consequences for the clinicians and the work system have been searched and organized; on the other hand, existing usability design principles specific to medication alerting systems have been synthesized. Results of both analyses have been matched together. Results.A systematic review identified 13 types of usability flaws in medication alerting systems. Consequences on the clinicians and the work system are varied: they greatly impede the clinicians and negatively impact the work system (e.g., alert fatigue, alert misinterpretation). Sixty-three usability design principles dedicated to medication alerting systems are identified. They represent six themes: improve the signal-to-noise ratio, fit clinicians’ workflow, support collaborative work, display relevant information, make the system transparent and provide useful tools. The matching between usability flaws and principles is quite good.Discussion.As a result of this work, a list of usability design principles illustrated by actual instances of their violation has been developed. It may help designers and Human Factors experts understand and apply usability design principles when designing and evaluating medication alerting systems. Usability applied to HIT is a recent research field that suffers from a deficit of structured knowledge. This work shows that it is possible to accumulate and structure usability knowledge. It could be carried on by developing a usability knowledge base dedicated to HIT in order to strive towards “evidence-based usability”.

With the increased demand for the utilization of computerized information systems by business users, the need for investigating the impact of various user interfaces has been well recognized. It is usually assumed that providing the user with assistance in the usage o-f a system would significantly increase the user's productivity. There is, however, a dearth of systematic inquiry into this commonly held notion to verify its validity in a scientific fashion. The purpose of this study is to investigate the impact of system-provided user assistance and complexity level of the problem on novice users' productivity in specifying database queries. The study is theoretical in the sense that it presents an approach adopted from research in deductive database systems to attack problems concerning user interface design. It is empirical in that it conducts an experiment in a controlled laboratory setting to collect primary data for the testing of a series of hypotheses. The two independent variables are system-provided user assistance and problem complexity, while the dependent variable is the user's query specification productivity. Three measures are used as separate indicators of query specification productivity: number of syntactic errors, number of semantic errors, and time required for completing a query task. Due to the lack of a well-defined metric for user assistance, the study first presents a generic classification scheme for relational query specification. Based on this classification scheme, two quantitative metrics for measuring the amount of user assistance in terms of prompts and defaults were developed. The user assistance is operationally defined with these two metrics. Four findings emerge as significant results of the study. First, user assistance has a significant main effect on all of the three dependent measures at the 1 percent significance level. Second, problem complexity also has a significant impact on the three productivity measures at the 1 percent significance level. Third, the interaction effect of user assistance and problem complexity on the number of semantic errors and the amount of time for completion is significant at the 1 percent level. Fourth, Although this interaction effect on the number of syntactic errors is not significant at the 5 percent level, it is at the 10 percent level. More research is needed to permit a thorough understanding of the issue of user interface design. A list of topics is suggested for future research to confirm or to modify the findings of this study.

No description available.

The number of elderly people moving into long-term care facilities is expected to increase as the population of people 65 and older continues to rise at a significantly high rate. Simultaneously, the number of people expected to be diagnosed with dementia will also increase unless a cure for this devastating disease is found. In the meantime, caregivers face many problems in providing healthy and humane treatments. One such problem that is a major concern for caregivers is controlling wandering behavior. This behavior often places patients in life threatening situations, and the current methods used by many facilities do not promote a high quality of life. The purpose of this study was to examine the effects of various tape patterns on the wandering behaviors of residents living in a special dementia care unit in Heritage Hall Nursing Home, Blacksburg, Virginia. Similar studies revealed that alternative methods using tape patterns could reduce exiting attempts at a fire exit door or could possibly increase these attempts. In order to address these inconsistencies, exiting attempts at a fire exit door were recorded during one baseline and two similar test conditions. It was found that exiting attempts was a serious problem in this unit as 40% of the residents attempted to exit the faci I ity during the study. The use of tape patterns reduced exiting attempts by 19.05% and 11.12%; however, this reduction was not statistically significant. In conclusion, the use of these tape patterns affected wandering behavior differently for each of the residents, suggesting that a multi-method approach for controlling exiting behavior may prove to be more successful when dealing with a heterogeneous sample and their multi-needs. / Master of Science