Movement Control

Movement Control Considerations in User Interface for ElderlyAs we age we suffer from reduced fine-motor control; reduced hand-eye coordination; slower response times; less control of speed, direction and force; decreased touch sensitivity; greater stiffness; more involuntary movement such as hand tremors; and difficulty gripping and manipulating small objects.  Coordinated movements are more difficult.  There are more small movements contained in each larger movement.  There is less accuracy in knowing one’s own body position.  These factors should inform designing a user interface for elderly people.

Older people have more difficulty tracking user interface pathways and targets.  It is harder and takes more time to capture small user interface targets.  There is more likelihood of overshooting user interface targets.  And elderly people are slower to recognize that they have captured a target.

In addition to challenges created by natural ageing processes, movement control can be affected by diseases that are more common in elderly people.  Arthritis affects approximately 50 % of adults over 65.  Parkinson’s disease affects approximately 1% of adults over 65 years.  But many more seniors suffer from other types of tremors.  Other physical problems may also arise in greater proportions in older adults.  For example, suffering a stroke may affect mobility and dexterity.

Older people appear to adapt to poorer movement control by trading control for speed and avoiding risk.  In other words, they will work more slowly and avoid user interface tasks that they are uncomfortable with, in order to minimize movement control problems.

In the general population, a mouse is more accurate than a finger.  But this is not the case in the older adult population.  Movement control impairment can create difficulty with click-hold, click-drag, and click-draw mouse actions.  It is not uncommon to observe seniors who use the mouse with two hands.

In general, older people perform better using touch interfaces.  This is consistent with research that shows that finger tapping ability declines later in the ageing process compared to other motor skill declines. However, seniors often have difficulty with continuous movements and problems executing coordinated touch interface gestures such as pinch, spread, multi-finger tap, and long press actions that are commonly used in software apps.  Swipe gestures may require training when used in a user interface for elderly people.


Movement - Finger Gestures
Graphics Courtesy Alvaro Cabrera

But touch presents its own problems in a user interface for elderly adults.  A study cited in PC Magazine investigated the way people interact with touch-screen devices and the health implications of prolonged use.  Researchers found that the added strain on the fingers, wrists, and forearms amounts to increased likelihood of problems such as Carpal Tunnel Syndrome.  To what extent this may disproportionately affect older adults is uncertain.

Older people generally have poor typing skills, a consequence of which is that they look at the keyboard instead of the screen while typing.  This makes it easier for seniors to miss that they are not typing within the input area that they intended.  It is unclear whether virtual keyboards alleviate or exacerbate this, but they certainly create new user interface design opportunities to minimize this problem in a user interface for elderly people.  Also, the effort of typing may compete for cognitive resources (memory, attention, learning).

Additional dexterity factors need to be considered in user interface design.  A single hand can be used to generate a (1) push force using any part of the hand, (2) pinch grip using the index finger and thumb to generate opposing forces, and (3) power grip using the palm and thumb together with all four fingers.  A push force requires the least amount of dexterity because there is no need for an opposing grip.  A two-handed task requires more dexterity because it involves a combination of pushing and gripping.  One hand is often required to hold or stabilize the object, while the other performs fine precision movements.

Mitigation Strategies:

  • The need for typing should be reduced where possible, for example, by using check boxes and “picker” type user interface elements.
  • Default to different keyboard styles, as appropriate, to minimize the need for toggling between styles. For example, default to a number pad control for numbers, or an email style keyboard where @ characters are used for email addresses, etc.  This is particularly important for software apps running on small devices where toggling can be confusing and error prone for seniors.
  • Virtual keyboard placement and use should be designed to make it easier for older people to type within the intended area, for example, by having the intended input area directly above the keyboard area.
  • We recommend making touch targets 2.5cm wide or larger (average adult thumb), but never narrower than 1.6 cm wide (smaller adult index finger). The height should be no less than the width. Because many personal computers are also becoming hybrid mouse/touch devices, follow these same size recommendations for mouse targets as well.  This will ensure that your user interface works for both.  See our article on Understanding Recommended Target Sizes for more detailed information.
  • Ensure that there is enough space between clickable user interface elements in order to prevent hitting multiple or incorrect targets.  The smaller your targets, the more space you will need between them.  We recommend a minimum of 0.5 cm.  Minimize the possibility of unintentional clicks or finger taps near the edge of the user interface where various operating system functions might be unintentionally triggered.  This is particularly important if a page allows scrolling or swiping.
  • In lists of bulleted links, make the bullet symbols clickable as well as the text in your user interface for elderly people.
  • Use static menus (a click leads to another user interface page) rather than “walking menus” (exposing a sub-menu on hovering). If there are walking menus, have them expand on a click (rather than a hover).  Time sub-menus to stay open for 5 seconds or until they’re clicked.  Do not use slide-out menus and hidden menu items that are difficult to target.
  • The structure of the user interface should be as shallow as possible to minimize the number of clicks or finger taps needed to navigate to a specific place or function. Older users should be able to reach any part of the user interface with a maximum of two or three clicks or finger taps.
  • Maximize use of simple 1-click or 1-tap actions. Some guidelines for older adults suggest treating multiple clicks or finger taps as single (where applicable).  In other words, if a person clicks on a clickable user interface element more than once, accept the first click and ignore the other clicks.
  • Minimize pointer interface click-hold, click-drag, and click-draw actions in your user interface for elderly people.
  • Minimize touch interface pinch, spread, multi-finger tap, and long press actions in any user interface for elderly people.
  • Minimize non-ergonomic tasks in your user interface for elderly people which cause physical strain, particularly interface elements that are likely to be used in sequence.
  • Design for one handed operation which generally requires a lower level of dexterity. Try to ensure the product can be used left or right handed.  If the user interface is designed for one handed use, ensure that it can be used comfortably by older people who might need to use two hands.
  • Avoid user interface actions that require both good vision and high dexterity simultaneously. Design so that only one of these is needed; or better yet, where neither is a requirement.
  • Avoid user interface controls that require simultaneous movements in different directions, for example, a control that requires pushing and twisting at the same time.
  • Enable easier gripping in your user interface for elderly people by providing a slightly deformable surface and maximizing the available contact area where possible.
  • Arrange gripping tasks so that they can be performed with the wrist in a neutral and straight position in order to improve user comfort and minimize pain for those with conditions such as arthritis.
  • Provide the option to operate the product by either reaching out the left or right arm. Try to avoid requiring both arms to be extended at the same time.
  • Ensure that products or services requiring public access (e.g., ATM’s or ticket kiosks) accommodate a range of reach that is suitable for older people, including those in wheelchairs. This may be a legal requirement in some places.

Below are some tools and resources that can assist user interface designers:

Related Articles: Understanding Recommended Target Sizes

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