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Safety Research Institute

Interfaces with devices and equipment

When human beings operate machinery, the possibility of operating the machinery increases if they are required to take an unnatural posture or when the arrangement of switches is difficult to identify. Moreover, wrong judgment tends to be made when the display screen is hard to see.

People that design devices and equipment do not always think in the same way as the people that use them. There are five perspectives related to interactions between human beings and devices.

(1) Physical aspects such as size, operating force, and contact surfaces.
(2) Cognitive aspects such as information presentation methods and operational techniques.
(3) Time-course aspects such as declines in attention and fatigue caused by monotonous work.
(4) Environmental aspects such as lighting, air conditioning. and noise.
(5) operational aspects such as education, training, manuals, and support for judgment, among others (Yamaoka).

Regarding cognitive aspects, the image of operating certain equipment, such as “this device is operated in this way” (the mental model) is sometimes different between the designer and operator. Designers of devices are required to think from the perspective of users and fully understand their characteristics to decrease faulty operations and make the devices easy to use.

When conducting a series of jobs, a person does not always operate one device at one time. Even when operating one device, sometimes different information is simultaneously presented. Human beings can attend to many things during a short time, but they cannot do that at the same time. When plural alarms sound at the same time or when a person is required to compare several indications and make judgements at the same time, it might be possible that the person overlooks the most important information because of the human characteristic that people automatically select information based on their experience.

When simultaneously operating many devices that were designed by different designers, it is important to see the whole system and check the operations of devices using an integrated way of thinking.