Computer input devices

       The computer mouse in brief

• The mouse must be anatomically suitable for the hand, i.e. it must correspond to the functional/anatomic shape of the palm and to the size of the hand. Simply put, it should lie comfortably in the hand.
• The mouse must be easy to use. It is important for the mouse to permit differentiated (changing) use of the hand and finger muscles.
• Task-specific use of the mouse should be possible on differently structured working surfaces (background).
• It should be possible to use the mouse with different fingers (e.g. index finger, middle finger). One-sided use of the index finger for typical click movements should be reduced, e.g. by using other fingers for the same function. If necessary, additional mouse buttons should be available for users with sensomotoric restrictions.
• There must not be any delays in transmission when using the mouse to access a required text field or a sign on the screen. Otherwise the user applies additional force by reflex when moving the mouse to reinforce the input command. This kind of psychological and physical reaction can cause muscular tension in the shoulders and wrists.
• The mouse must be used intuitively and in accordance with the specific tasks. Transmission of the mouse movements to the cursor on the screen should be as expected, i.e. direct.
• It shall be possible to adjust the response speed of the computer mouse to support the user's individual way of working.
• In schools, universities or other areas where computer workstations are used by different people, computer mice that can be used by both left- and right-handed users are useful. Special vertical mice, which have a tilt or swivel mechanism, make it quick and easy to switch. For intuitive use, the key assignments should change automatically.
• There are also computer mouse with a trackball. They are sometimes used in areas where a classic moveable mouse cannot be used. A mouse with a trackball keeps its place, because the movement of the cursor is done by an easily rotatable ball (trackball). The use of a trackball should be weighed against a classic or vertical mouse.

       The centred computer mouse in brief

• The centred computer mouse must be suitable for the hand, i.e. it must correspond to the functional-anatomical conditions of the hand and the size of the hand. Simply put, it should be comfortable to use.
• The mouse must be easy to use. It is important to allow the hand and finger muscles to be used as alternately as possible.
• The mouse buttons should be operable with the fingers of both hands. Under certain circumstances, additional mouse buttons (e.g. for the thumb) should be available in the case of sensorimotor impairments.
• When using the mouse to access a desired text field or a character on the screen, there should be no delays in transmission.
• The movement of the mouse must be intuitive and appropriate to the task. The transfer of the mouse movement to the movement of the cursor on the screen shall be in conformity with expectations, i.e. direct.
• It shall be possible to adjust the reaction speed of the centred computer mouse to support the user's individual way of working.

       The keyboard in brief

• It must be possible to use the keyboard holding the arms near to the body with the shoulders relaxed. 
• It must be possible to use the keyboard without bending the wrists. The forearms can be supported to relieve strain. This can be done, for example, through the flat design of the keyboards on the tabletop, a palm rest or an optional forearm support. When typing, the palms or wrists do not come into contact with a disturbing surface.
• The keys work easily. Short, easy key strokes are kind to joints, tendons, muscles and ligaments.

• The keys must have clearly visible symbols. These symbols should be wear-resistant.
• The keyboard must allow flexible application. Wireless versions naturally offer the greatest possible flexibility.
• For easy familiarization, the construction of the keyboard must meet the expectations of a standard commercial keyboard.