Most products require physical manipulation of controls and manual handling. The hands are used to grasp, move and exert forces to use and operate various products. Objects can be grasped, pushed and pulled. The human hand is composed of four fingers and an opposable thumb, which is key to many dexterity tasks.

We can exert clamping forces between fingers and also clamp and hold larger objects in the palm of the hand. Individual fingers can be used to exert pulling and pushing forces. We often use both hands at the same time to manipulate objects. This coordinated movement requires strength and dexterity in the fingers together with sensory capability and motor control.

There are many causes of pain that can limit dexterity. Arthritis is one example that is particularly prevalent for older people, causing stiffness, swelling and pain in the joints. The satisfaction level for using a product is seriously affected when it causes pain, even if the product is still usable.

Many able bodied people will experience temporary bruising or breakages that can affect their dexterity capability. This causes particular frustration when attempting to use products that require unusually high levels of strength or two-handed co-ordination.