Design Considerations
Requirements Gathering
Envisionment Methods
Evaluation
Other
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Touchscreens
Touchscreen Systems are:
- Systems requiring pointing and selection only
- For advertising, product information
- As public information systems, for example, in museums, as city guides
- Kiosks are typically embedded in some sort of cabinet, so that they
can stand alone and are built for rugged environments
- Use a simple point-and-click interface
- Animation and large fonts help attract users to kiosk applications.
The kiosk design (cabinet) should also be attractive
- Touchscreen devices can be used for advising customers or clients. This
can happen together with a consultant like a physician or a salesman,
or the users do this alone.
- Images and photos can be used for illustration (esp. in museums)
Discussion 1
- What are the similarities and differences between keyboard and touch
screen interfaces?
- What sorts of applications are better suited to touch screens? Why?
- What potential disadvantages have touch screens compared to keyboards?
Touchscreens are Best Suited to Applications Where...
- Opportunity for training is low
- Frequency of use per person is low
- Accurate positioning is not required
- Little or no text or numerical input is required
- Desk space is at a premium
And Not Suited to Applications...
- Requiring training/trained users
- With high-frequency use per person
- Requiring accuracy
- Requiring a lot of typing
Touchscreen Pros
- Direct: Direct pointing to objects, direct relationship between hand
and cursor movement (distance, speed and direction), because the hand
is moving on the same surface that the cursor is moving, manipulating
objects on the screen is similar to manipulating them in the manual world
- Fast (but less precise without pen)
- Finger is usable, any pen is usable (usually no cable needed). No keyboard
necessary for applications that need menu selections only, so saves
desk space
- Suited to: novices, applications for information retrieval, high-use
environments.
Touchscreen Cons
- Low precision (finger): Imprecise positioning, the finger may be too
large for accurate pointing with small objects where a pen is more accurate.
- Hand movements (if used with keyboard): Requires that users move the
hand away from the keyboard; a stylus also requires hand movements to
take up the pen.
- Fatigue: Straining the arm muscles under heavy use (especially if the
screen is placed vertically).
- Dirt: The screen gets dirty from fingerprints.
- Screen coverage: The user's hand, the finger or the pen may obscure
parts of the screen.
- Activation: Usually direct activation of the selected function, when
the screen is touched; there is no special "activation" button
as with a light pen or a mouse.
Touchscreen Design
Screens
- Full screen - Applications should be run full screen.
- Backgrounds - Bright background colors (no black!) hide fingerprints
and reduce glare. Dithering or other patterned backgrounds help the eye
focus on the screen image instead of reflections, even in areas where
there are no icons or menu choices
- Handedness - As many users are left-handed, the screen layout should
be switchable between a version for right-handed users and a version for
left-handed users.
- Screen Reversal - The screen reversal should affect mainly the large
building blocks of the screen layout. Whether the controls themselves
should also be mirrored, depends on how much interaction is adversely
affected by the standard layout of the control. For instance, it depends
on, whether a standard control is obscured, if operated with the left
hand.
Maintaining Screen Space
As touchscreens usually are of fixed size and screen elements have to be
large enough to be operable by fingers, screen space is at premium with
touchscreens. Here are some proposals for overcoming the space limitations
of touchscreens.
- A tabstrip can be used to virtually enlarge a screen by providing a
device that enables the users to switch between different views. A tabstrip
consists of a "tab area" which contains buttons for switching
the view, and of a "presentation area" which is usually of fixed
size (it may be scrollable) and displays the different views. Suited to
manual selection of items with finger.
- Switchable Areas - A similar technique consists in assigning certain
screens areas to fixed functions like data display, function key area,
keypad area etc. Push buttons can be used to exchange to elements in such
a fixed area, for instance to switch between different list views , different
versions of a keypad , different button sets or groups
Screen Changes
Do Not...
- Do not make the screen scrollable like long HTML pages!!!
- Do not use a multiple-window interface
General Interaction Issues
- Use: a simple point-and-click interface with large buttons.
- In general do not use: dragging, double-clicks, scroll bars, dropdown
menus, multiple windows, or other elements that can confuse the common
user and interfere with usability and efficiency.
- Cursor: Turn the cursor off - user will focus on the entire screen instead
of the arrow and their thinking and action will be direct instead of indirect.
Buttons
As touchscreens are mainly used for point-and-click applications, most
touchscreens are filled with pushbuttons and areas for data display and
entry. Therefore, buttons play an important factor in the design of touchscreens.
- They should be a minimum of 3/4 by 3/4 inch (2*2 cm) and at least 1/8 inch
(3 mm) apart for finger-operated touchscreens.
- Use large and discrete targets that are spread out on the screen
- Buttons should give some sort of feedback as to their state (on/off, active/inactive,
activated (transient), etc.)
- Immediate feedback is critical to reassure
the user that their touch registered.
- Visual feedback (highlighting, 3 D-effect)
should occur in response to button presses.
- Auditory feedback (click, ...)
is sometimes also appropriate.
Data Entry
Entering values can become very tedious on touchscreens. Value entry should
be restricted to few values. The basic interaction modes are:
- Multiple Clicking - Spin Buttons and scroll buttons need less space
than discrete options, but require users to click several times or even
cycle through the possible values or options.
- Dragging - For mouse-operated or pen-based systems, dragging is a valid
and often efficient option. For finger-operated systems, however, these
options should be avoided, if possible. Drag operations are imprecise,
relatively slow, and smear the screen surface. Sliders and scroll bars
are ways to set discrete or continuous values. These options are better
suited for large and/or continuous value ranges.
- Numbers and Letters - Touchscreens are not well suited for data entry.
In addition, there are few touchscreens which provide an additional external
numeric or alphanumeric keypad.. Data entry is typically provided through
virtual keypads or keyboards, which can be placed on the screen on demand.
For applications where numbers or letters are frequently entered, the
virtual keypad should stay permanently on the screen.
- Key arrangement for text entry: Alphabetic keyboards on the screen may
have a different order than usual typewriter keyboards. Make the keyboard
layout switchable or even customizable. Users may not be proficient typist
and are not familiar to the typewriter keyboard layout. A different ordering,
e.g. alphabetic, may be better suited for them. Use the standard layout
only when people are used to it and find the keys faster with this layout.
- Minimize text entry: The conventional keyboard layout is not optimal
for 10-finger typing. Alternative layouts have been proposed, but are
not widely used. Both, the alternative and the standard layout are used
for multiple-finger entry. This is not the case with touchscreens. Here
people use just one finger, which slows down text entry considerably.
Therefore, keep text entry to a minimum or better even avoid it totally
on touchscreens.
Scrolling
With touchscreens, it is easier to scroll by pointing than by dragging.
Therefore:
- Do not use conventional scroll bars, even if they are enlarged, but
to use simple pushbuttons instead. Especially, do not use a "thumb"
for scrolling the list by dragging.
- Scroll buttons should follow the usual guidelines for buttons. Better
make them larger than too small
- Do not use scrolling for the screen itself, but only for data display,
i.e. for fixed areas on the screen. At best, do not use any scrolling
at all.
- In some cases you can replace scrolling through controls that display
only a part of the items or functionality on the screen and that allow
for easy switching between the views by pointing to buttons. A tabstrip
is such a screen element.
Metaphors
Metaphors provide users with a familiar environment on the screen. This
allows users to transfer prior real-world knowlegde to an application: they
learn new applications faster and relearn rarely used applications easier.
So, metaphors might just be THE solution for touchscreens where users are
often untrained. However, there are also some caveats:
- Metaphors may break and confuse users, because they require interaction
that does not make sense to the users, or they make the application behave
unexpectedly.
- Often applications are abstract, and there is no suitable real-world
metaphor available.
- Metaphors may waste precious screen space, because the graphical elements
that maintain the metaphor (e.g. a room) need space to be realistic enough.
- The graphics for the metaphor may be too detailed to allow fast orientation
and operation.
Exercise
Read 'Designing
a Touch Screen Kiosk for Older Adults: A Case Study'
Given the points we have discused in class, in small groups of 2/3, analyse
the design of the fitness tracking system.
- Identify, with reasons:
- Good features of the system
- Features which could be improved
- Suggest improvements to the system
Using an image editing programme, do a quick mockup of the improved system.
Further reading