Assignment 2 Interface Metaphors prepared by Gerwin Schalk, MS [email protected] http://www.gerv.org Foundations of HCI Usability Dr. Roger Grice Rensselaer Polytechnic Institute Albany, NY October 2000 Contents 1 Introduction 1 2 The Metaphor 2 2.1Description................................ 2 2.2Users.................................... 3 3 Metaphor Assessment 5 4 Metaphor - Properly Implemented 6 4.1TheTrashcan............................... 6 4.2Folders................................... 6 4.3MovingFiles/Folders........................... 7 5 Metaphor Violations 8 5.1DataTypes................................ 8 5.2Shortcuts................................. 9 5.3DriveLetters............................... 9 5.4InappropriateUseofVisualEffects................... 10 5.5WebPageasDesktop?.......................... 11 6 Suggestions 12 6.1DataTypes................................ 12 6.2Shortcuts................................. 12 6.3DriveLetters............................... 12 6.4InappropriateUseofVisualEffects................... 13 6.5WebPageasDesktop?.......................... 13 i 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 1 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 andactionsrelatedtoanactualdesktop: 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 2 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. 5 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,orfull 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: 6 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. 8 CHAPTER 5. METAPHOR VIOLATIONS 9 double click rename 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.