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Limited information is available regarding ergonomic foldable display device forms. This two-stage study involving young South Koreans (divided into three hand-length groups) was conducted to determine ergonomic forms for hand-held foldable display devices considering folding/unfolding comfort and preference. Stage I obtained the suitability of three screen sizes for five tasks. Stage II evaluated 14 different bi- and tri-folding methods considering screen size, folding direction, and folding time. The effects of hand length were all non-significant. Screen size preferences were task-dependent; small screens were preferred for making calls, and medium screens for web searching and gaming. Folding methods affected folding/unfolding comfort and preference; outward screen and Z-shape screen folding were the most preferred bi- and tri-fold concepts, respectively. Screen protection and access appeared to be competing factors in the user preference determination process. Foldable screen size and folding method should be determined by considering tasks, folding/unfolding comfort, and user preferences.

International audience; Nowadays touch technology is growing and developers try to make it ever more intuitive and easier to use. This present work focused on the upper limb joint coordination during the achievement of puzzles on touch screen. A 5-inch and 10-inch devices were used to perform 9 and 16 pieces puzzles dragged with digits. The conclusions showed an increase in joint solicitation with the number of piece and the touch screen size. Moreover, three interactions strategies proved to be an evidence: the 'wrist strategy' preferentially implying wrist flexion/extension, the 'elbow strategy' preferentially implying the elbow flexion/extension and the 'neutral strategy' mobilising equally the two joints. From an ergonomic point of view, the data about how the upper limb segments are mobilised while interacting with the screen could be relevant to increase the adaptability of the devices to the user, including users with motor impairments. Practitioner Summary: Information about the biomechanical organisation of movement during interaction with touch devices appears relevant in order to develop applications adapted to the motor capacities of users. From the analysis of joint angles when performing several times a puzzle with healthy subjects, three motor strategies were highlighted.

We examined the systematic effects of display size on task performance as derived from a standard perceptual and cognitive test battery. Specifically, three experiments examined the influence of varying viewing conditions on response speed, response accuracy and subjective workload at four differing screen sizes under three different levels of time pressure. Results indicated a ubiquitous effect for time pressure on all facets of response while display size effects were contingent upon the nature of the viewing condition. Thus, performance decrement and workload elevation were evident only with the smallest display size under the two most restrictive levels of time pressure. This outcome generates a lower boundary threshold for display screen size for this order of task demand. Extrapolations to the design and implementation of all display sizes and forms of cognitive and psychomotor demand are considered.

Influencing factors on speed and accuracy of cursor positioning using a mouse and the learning progress of subjects were analysed in experimental studies. 64 subjects (44 of whom were female) with an average age of about 24 years had to conduct 1200 cursor positioning trials over a period of two days. The results show that the c:d-ratio, that is, the mouse movement distance necessary per distance unit of the cursor movement, did not influence the positioning time. Rather, the target size (the necessary accuracy), the mouse movement distance, and (to a lesser extent) the display size are the decisive factors. In order to shorten the mouse movement distance for longer target distances, a speed-dependent variable gearing ratio is often implemented. This increases the distance the cursor is moved for the faster mouse movements, but it also violates the proportionality of mouse and cursor movement distances in the interest of a shorter mouse movement distance. For the target sizes used in this study, the speed...

The paper describes (1) the development of a simulator and (2) the first results of a training technique for the identification of plant failures from control panel indications. Input or signal features of the task present more simulation fidelity problems than its response or output features. Current, techniques for identifying effective signals, e.g. ' blanking-off ' information, or protocol analysis, bias any description of problem solving since they require serial reporting, if not serial collection, of information by the operator. They also require inferences as to what is an effective item of information. It is therefore argued that simulation should preserve all those features which may in principle provide, or influence acquisition of, diagnostic information, specifically panel layout, instrument design and display size. Further fidelity problems are the stress from operating in a dangerous environment; stress from hazards or sanctions following mistaken diagnosis; and the stress of diagnosing in a short time interval. The simulator uses bock-projection to life size of slides of control panel mock-ups by a random access projector. Under an adaptive cumulative part regime, trainees saw on average 89 failure arrays in 30 min, an obvious advantage over the operational situation. In a test 24 hr after training, consisting of the eight faults each presented four times in random order, 4 out of 17 trainees made only one error in 32 diagnosos; the other trainees performed perfectly. Subjects' reports indicate very different solution strategies, e.g., recognition of alarm patterns; serial instrument checking determined by heuristics of plant functioning. Several features of performance arc consistent with the view that trainees use a minimal number of dimensions for correct discrimination and that these change as the number of different fault arrays increases. It is argued that this training regime should reduce stress. In particular it is argued that, according to current theories of stress, the fewer dimensions needed for diagnosis, the more robust will be diagnostic performance in dangerous environments.