assignment 2 interface metaphors -...
TRANSCRIPT
Assignment 2
Interface Metaphors
prepared by
Gerwin Schalk, [email protected]
http://www.gerv.org
Foundations of HCI UsabilityDr. Roger Grice
Rensselaer Polytechnic Institute
Albany, NY
October 2000
Contents
1 Introduction 1
2 The Metaphor 2
2.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 Users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3 Metaphor Assessment 5
4 Metaphor - Properly Implemented 6
4.1 The Trashcan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2 Folders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3 Moving Files/Folders . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Metaphor Violations 8
5.1 Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.2 Shortcuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.3 Drive Letters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.4 Inappropriate Use of Visual Effects . . . . . . . . . . . . . . . . . . . 10
5.5 Web Page as Desktop ? . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6 Suggestions 12
6.1 Data Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.2 Shortcuts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.3 Drive Letters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.4 Inappropriate Use of Visual Effects . . . . . . . . . . . . . . . . . . . 13
6.5 Web Page as Desktop ? . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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Chapter 1
Introduction
This paper describes the desktop metaphor that was used to guide the implementa-
tion of the user interface of the MS-Windows operating systems (in particular, the
metaphor used starting with Windows 95 ). Windows 95 has been introduced in
1995 and it or its successors (which all sport the same interface) has/have a domi-
nant market share. While commercially successful, the interface has been target of
constant criticism from technology professionals, who claim that it is a bad copy of
the Macintosh interface rather than new innovation (interestingly, Apple has filed a
lawsuit against Microsoft in that regard that they ultimately lost1).
We will describe the exact nature of the used metaphor and the users who will use
the interface. We will discuss how appropriate the choice of the metaphor was for the
interface and discuss suitable and inappropriate implementations of the metaphor.
We will conclude with some concrete suggestions for improving the interface.
1Every, D.K. Microsoft, Apple and Xerox. The History of the Graphical User Interface.http://www.mackido.com/Interface/ui history.html
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Chapter 2
The Metaphor
2.1 Description
The metaphor underlying Windows’ interface is the ”desktop metaphor.” As the
desktop is a real-world and well conceptualized object, so should the virtual desktop.
The desktop metaphor contains a lot of structure, that is, a lot of implications, items
and actions related to an actual desktop:
It contains a large working space
It contains drawers
Drawers can be opened, closed, and can contain documents or subcompart-
ments
The look-a-like of a document implies its use
Documents can be moved into other drawers
One can place documents, folders, or items anywhere on the desktop
A desktop can have a certain style or ”theme”
Actions are executed by specifying the document, and then, subsequently, the
action
As noted in1, a metaphor is useful to conceptualize the model behind the inter-
face, given that its structure is appropriate. Although the global applicability of this
idea is somewhat under debate, it seems that it certainly holds true for novice users.
On the other hand, a metaphor can be dangerous by providing false or inapplicable
1Laurel, B. The Art of Human-Computer Interface Design, p. 70-71. Addison Wesley, 1990.ISBN 0-201-51797-3
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CHAPTER 2. THE METAPHOR 3
Figure 2.1: The ’desktop’ of any MS-Windows operating system
implications, or if the structure of the interface is not compatible with the structure
of the metaphor.
In any case, the MS-Windows interface tries to implement this metaphor, some-
times successfully, but it also sometimes fails. It might fail, because not enough
resources have been spent for designing the interface, because of backwards compat-
ibility issues, or because the desktop metaphor does not, or inappropriately, cover a
specific wanted feature.
2.2 Users
The targeted average user for the interface of MS-Windows is certainly the non-tech
savvy user. First of all (and maybe most importantly), this might be because they
represent the majority of all users. As an interface can never cover the needs of
all users, why not optimize it for the majority ? Certainly, this explains some of
CHAPTER 2. THE METAPHOR 4
the inappropriate implementations discussed in chapter 5. Power users will not be
satisfied by the limited power of the ”select-and-define action” execution scheme,
and might therefore have to use more sophisticated interfaces, e.g., programming
languages, other operating systems (e.g., Unix). We listed some of the implied
characteristics of the typical user:
Feature Description
Age Group above reading age
Race not implied
Gender not implied
Education not implied
Occupation not implied
Culture Western
Reason for using a computer mostly business
Technical experience low to moderate
Task profile maybe repetitive, but simple
Derives satisfaction from understanding the interface
Table 2.1: User Profile
Chapter 3
Metaphor Assessment
First of all, it is likely that it is not possible to create an easy-to-use or conceptu-
alizable interface that can account for all degrees of freedom of a modern personal
computer. However, one of the goals for the implementation of Windows’ user in-
terface was that it should appeal to the majority of the users. In addition, it should
be as easy as possible to use, hide unnecessary technical details from the user, and
provide a conceptual model that, even though it might not reflect the system model
of a computer, allows for inferences made from real-world experiences.
In this sense, and at least for the current generation of available input devices,
choosing a desktop as the interface metaphor certainly serves the intended purpose.
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Chapter 4
Metaphor - Properly Implemented
Of all the various structural implications of the metaphor described in chapter 2,
MS-Windows implements many: the desktop encompasses a large working space,
drawers, documents, and it can have a certain style. In addition, documents can be
moved, executed, or stored in the trashcan. The following examples represent good
implementations of the desktop metaphor:
4.1 The Trashcan
The trashcan is actually an extension of the desktop metaphor – who (except Prof.
Grice ;-)) has a trashcan on his/her desk ? Still, the trashcan correctly implies
its functionality. Documents can be thrown away, or trashed, and they can also be
restored, if the trashcan has not been emptied. Also, the trashcan can be full.
Figure 4.1: One possible icon for the MS-Windows trashcan, or ”Recycle Bin,” if
empty, or full
4.2 Folders
Folders in MS-Windows are another example of a good implementation of the desk-
top metaphor. Folders can contain documents, and even share the look-a-like with
their real-world counterparts:
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CHAPTER 4. METAPHOR - PROPERLY IMPLEMENTED 7
Figure 4.2: One possible icon for a folder in MS-Windows
4.3 Moving Files/Folders
As in the real world, files or folders can be moved to another location. The im-
plementation provides feedback that is oriented towards the desktop metaphor, by
showing documents flying from one folder into another.
Figure 4.3: Graphical feedback while files/folders are moved in MS-Windows
Chapter 5
Metaphor Violations
In this chapter, we discuss specific examples of instances, in which the desktop
metaphor is particularly inappropriate, or where it was implemented especially
poorly.
5.1 Data Types
In any MS-Windows operating system, the type of a file is solely determined by the
file’s extension. A user, on the other hand, is likely to link a file to its semantical
context, e.g., he or she will expect a text document to look (its icon) and behave
(double-clicking invokes text editor or word processor) like a text document, regard-
less of its name or extension (especially, since the definition of the extension as ”the
dot and the three characters after it,” itself is arbitrary).
Now, let’s see how this poor implementation can result in major problems: in
figure 5.1, there is a file (”GRAZ BCI.JPG”), which contains an image. Its icon
correctly symbolizes a picture (although the icon itself is generic and the same for
any picture). After renaming the file to ”GRAZ BCI.TXT,” the file’s icon changes
to a generic text document icon. Clicking on it incorrectly starts a text editor that
brings up a window containing only trash.
On the Macintosh, however, data and context are seperated into a ”data fork,”
containing the actual data, and a ”resource fork” that contains the actual icon, the
type of the data file (e.g., image, sound, text) and the creating application of this
file. These two seperate parts are transparent to the user and the operating system
will always launch the correct application, even if the file is transferred to a different
computer containing a different set of applications.
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CHAPTER 5. METAPHOR VIOLATIONS 9
rename
double
click
Figure 5.1: Windows’ improper data type handling
Figure 5.2: Windows’ attempt to locate the file the shortcut is pointing to
5.2 Shortcuts
Another example of poor implementation is Windows’ shortcut system: creating a
shortcut to a file in a computer is similar to, for example, labeling a divider in a
folder. In both cases, activation of the reference pulls out the actual file.
In the real-world, the reference would always point to the actual file, i.e., in
abovementioned example, it would not matter, if the whole folder would be moved
to a different place. Accessing the same divider would still reveal the same document.
On the MS-Windows platform, however, a shortcut contains a ”hard-coded”
link to the actual file. If this file would subsequently be moved, the link will not
be updated, and accessing it will prompt Windows’ pathetic attempt to locate the
original file (see figure 5.2).
5.3 Drive Letters
For backward compatibility reasons, even current versions of the MS-Windows oper-
ating system contain the notion of a ”drive letter.” Clicking on the ”My Computer”
dialog box reveals several (nicely looking) icons (see figure 5.3), most of them cap-
tioned by a letter.
CHAPTER 5. METAPHOR VIOLATIONS 10
Figure 5.3: The ”My Computer” dialog in MS-Windows
Figure 5.4: Windows’ dialog box, after accessing ”drive G:”
For a reason not obvious to the user, these drive icons are always present, even
for drives with removeable media (e.g., floppy drive, ZIP drive, CD-ROM), where
no media is present in the drive.
Trying to access one of these apparently present (but actually physically not
present) resources brings up another dialog box that does not necessarily help to
clarify the situation (figure 5.4).
5.4 Inappropriate Use of Visual Effects
One of the major goals (at least that’s what marketing led us to believe) in the
development of the Windows 95 operating system was user friendlyness. For the
first time on MS-DOS based systems, it implemented the desktop metaphor. One
CHAPTER 5. METAPHOR VIOLATIONS 11
Figure 5.5: The ”Active Desktop” feature
example illustrates, how poorly this was executed:
In the Windows 95 ”Plus” package, users could choose a variety of styles or
”themes” for their desktop (as they somewhat also can on real desktops). However,
some of these themes totally lost their connection to the original metaphor, e.g., one
where a mouse pointer would change it shape to an animated nail that was hit by
a hammer, every time the user clicked on the closing button of a window !!
5.5 Web Page as Desktop ?
One example for a particularly inappropriate implementation is one of Microsoft’s
new features – the ”Active Desktop” (see figure 5.5). While the original metaphor
of a computerized version of a real desktop with files accessible on it is certainly
valid and useful, having a web page as desktop background seems more the product
of other factors than interface engineering (as the tech-savvy reader will agree).
Chapter 6
Suggestions
In this chapter, we’ll address each metaphor violation or poor implementation de-
scribed in the previous chapter, and provide concrete suggestions for improvement:
6.1 Data Types
As explained, on the Macintosh, a file’s data type, its creator application, and its
iconic representation is stored, along with the actual document data contents. This
”additional” data is transparent to the user, i.e., the user does not have to know the
details on how this information is actually physically stored. MS-Windows could
implement this scheme in the same fashion the Macintosh does. This would certainly
conform better with the desktop metaphor, since in the real world, document type is
also implicitly present in the document representation (e.g., a sheet of paper implies
a text document).
6.2 Shortcuts
On the Macintosh, a shortcut to a file is always linked to the actual physical repre-
sentation of the file, even if the file is moved. Once again, future implementations of
MS-Windows could sport the same functionality that would also be more consistent
with the desktop metaphor.
6.3 Drive Letters
As it is on the Macintosh, physical or logical devices are represented by an icon and
a name, if they are present. If there is no CD-ROM inserted in the CD-ROM drive,
then there is no user feedback for one. Future versions of MS-Windows could get
rid of the static drive letter scheme and implement the same dynamic design.
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CHAPTER 6. SUGGESTIONS 13
6.4 Inappropriate Use of Visual Effects
Some of the visual effects in MS-Windows are (at least in the author’s opinion)
the best example of an engineer’s view on what users might find exciting. On the
Macintosh, however, visual effects always try to have some real-world relevance, e.g.,
the software installation process: software installation is accompanied by a changing
mouse pointer; a pointer that resembles one hand using the fingers to count from
one to five, indicating a process the user has to wait for.
6.5 Web Page as Desktop ?
Being able to have a web page as a desktop background neither has anything to do
with the original desktop metaphor, nor does it provide any functional advantage.
The only reason for its implementation (in the author’s opinion) is of legal nature in
the antitrust case Microsoft vs. DOJ. Future versions of MS-Windows could easily
drop this feature – a feature that might be the best example of ”featuritis,” features
added for different reasons than usability.