& # 8211 ; Computer Interaction From The Perspective Of The Design Essay, Research Paper

System metaphors appear to be pulling more and more attending and you frequently hear the term banded about in diaries and conference proceedings. The purpose of this essay is to analyze the possible utility of metaphors to the users and interior decorators of systems, concentrating, in peculiar, on the human-computer interface. It will hopefully be established whether system metaphors are phenomena worthy of serious idea or whether it is merely an empty term with no more than intuitive entreaty which will be passed over and bury with clip. The basic thought behind a metaphor is to understand a new construct in footings of one which is already familiar and understood. A good known metaphor is that of Rutherford & # 8217 ; s comparing of the H atom to the solar system. Lakoff and Johnson ( 1980 ) see linguistic communication to be structured metaphorically and claim that this reflects the construction of idea procedures in general: Metaphor is permeant in mundane life, non merely in linguistic communication but in idea and action ( Lakoff & A ; Johnson 1980, p3 ) Many instructors have used metaphor and analogy to ease their students larning and so analogy seems to be a cardinal facet of larning. Metaphors can be distinguished from theoretical accounts by the partial nature of the correspondence between the old and new construct. What is so the relevancy of metaphor to human-computer interaction? A important involvement in HCI is commanding system complexness. This affects the learnability and easiness of usage of a system and accordingly its credence by users. If a system is non accepted by users so in many ways it is a failure. There are different attacks to cut downing system complexness and bettering learnability and serviceability: foremost the figure of actions the user has to put to death and the figure of procedures and constructs to be remembered can be reduced ; instead, alternatively of cut downing the initial complexness interior decorators could increase the initial acquaintance of a system by utilizing interface actions, processs and constructs which make usage of specific bing cognition and experience that users have of other spheres. This is the broadened significance of the term metaphor which is employed in HCI research. Metaphors can be of usage for both the user and the interior decorator, since what is good for the one is often good for the other. The user & # 8217 ; s behavior at the interface is frequently believed to be shaped by the mental theoretical account thet he or she has of a system and undertaking. The cognition that it represents enables an adept user to foretell and understand a complex system. Metaphors can be regarded as short-cuts along the way to geting a comprehensive mental theoretical account. They can be used to impart a familiar air to unfamiliar fortunes which might otherwise turn out confounding. Gentner ( 1980 ) speculates that the difference between experts and novitiates can be explained in footings of analogies: & # 8230 ; the expert has an abstract planetary theoretical account with wide range, while the novitiate has a medley of rich, merely locally utile theoretical accounts & # 8230 ; naif theoretical accounts of scientific discipline appear more like expressive analogies than do adept theoretical accounts There is grounds that even when non provided with a metaphor users spontaeously create them anyhow as portion of the understanding procedure ( Carroll & A ; Thomas 1982 ) . It would be utile if interior decorators could expect likely metaphors in order to steer users towards utile ways of believing about a system and forestall them from choosing inappropriate metaphors which would possibly impede larning. As Carroll, Mack & A ; Kellog ( 1987 ) point out & # 8220 ; the usage of interface metaphors is permeant and turning in interface design & # 8221 ; , nevertheless it is non clear to what extent interior decorators are cognizant that they are utilizing metaphors. At present it seems to be a instead intuitive and hit-or-miss procedure. A metaphor which has entreaty for a interior decorator may non necessarly convey the right constructs to a user and may hold broader deductions which are non superficially apparent. These and many other factors seem to connote that user interface interior decorators should larn all they can about what metaphors are, how they have consequence and how they can be incorporated into user interface and system design in a systematic mode. & # 8220 ; & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” This following subdivision aims to show some of the chief metaphors which are soon used, every bit good as discoursing more experimental metaphors. The metaphor of a typewriter is often used to assist people get the hang word processing systems. Much utile cognition about keyboards and the act of typing itself can be applied to word processing, cut downing the complexness of the system and doing it easier to larn. Whiteboard and Chalkboard are both systems which exploit prior knowledge about the really same real-world objects every bit good as properties of these objects such as a common work infinite for concerted groups, and freeform text and artworks. Other often used metaphors include document and concern signifiers, but possibly the best known metaphor is that of the desktop, a complex composite metaphor. Commercial illustrations of this metaphor include the Xerox Star system every bit good as Apple & # 8217 ; s Lisa and Macintosh systems. This metaphor is intended to enable users to pull strings familiar office objects in familiar ways and feats people & # 8217 ; s ability to utilize the infinite around them for organizing and hive awaying things. For illustration, a papers booklet can be retrieved from a filing cabinet. Documents can be represented as icons and simultanious activities in different topographic points as tonss of paper, as on a existent desk top. Files that are nolonger needed can be thrown off in the rubbish bin. The physical universe metaphor of direct use is often used for indicating and choosing different objects and tools. Desktop tools embody additions to the desktop metaphor. They are little, separate applications which are similar to office tools such as notepads, calenders and reckoners. Physical universe or existent universe metaphors normally involve existent universe objects and their properties. For illustration Boxer, an object-oriented scheduling environment, uses boxes and spacial belongingss, such as containment, to stand for semantic belongingss of programming concepts. More by and large these can be viewed as belonging to the spacial metaphor which uses thoughts related to ocular representation and direct use, two closely related constructs. Visual image can be a powerful assistance to comprehension and conceptualisation as demonstrated by the usage of artworks and even life. Navigation through an information infinite is being investigated as an effectual agencies of recovering information and several systems have been developed around this construct. Bannon et Al ( 1983 ) developed a multiple practical workspace intended to assist users organize Windowss efficaciously. Each workspace, called a Room, holds a aggregation of Windowss related to different primary undertakings. Users can travel between Rooms by choosing the appropriate Door icon. Users are described as being able to voyage their manner through the system and seamster room contents to their demands. To me this suggests the different suites of a house which contain different functional objects, for illustration, a kitchen with a cooker, a electric refrigerator, etc. Many hypertext systems present some agencies for exposing and voyaging through a web construction. All of these systems integrating spacial metaphors raise inquiries. For illustration, how can non-numerical information be positioned in information infinites? How can concepts be mapped onto a two or three dimensional position? How can we supply users with navigational AIDSs to assist them happen what they want and halt them from acquiring lost in complex informations constructions? Hammond & A ; Allinson ( 1987 ) reference this last inquiry with their travel metaphor which provides different hunt modus operandis such as usher, circuit, map and jaunt. There are besides inquiries about peoples memory for spacial location. Harmonizing to Jones and Dumais ( 1986 ) spacial memory deteriorates more quickly than symbolic memory as the figure of points additions. It is besides of import to bear in head that retrieval paths which are utile in real-world retrieval state of affairss need non restrict the pick of retrieval paths in computerized systems. If, for illustration, I want a specific papers there is no ground to pall myself out sifting through files in an electronic office or walking up and down the shelves of an electronic library. More direct efficient entree based on content is a reasonable attack. This touches on the fact that metaphors should non be taken excessively literally. Problems associated with recognizing the boundaries of a metaphor every bit good as their possible to curtail the design and usage of a system are related to this point and are discussed in more item subsequently. Robert Riekert, cited by Carroll, Mack & A ; Kellog ( 1988 ) , uses a telecasting set metaphor to battle his pupils frights about computing machines in big computing machine literacy categories. Interestingly this metaphor is directed more at reassigning the pupils attitudes than their cognition. Although people by and large do non cognize much about the internal operation of a telecasting they are non afraid of it. & # 8220 ; & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” It is apparent that the usage of system metaphors is a widespread design technique, but is their any empirical grounds indicating to the manner in which they may impact the user? Johnson-Laird ( 1981 ; 1983 ) shows that our ability to work out a job depends on the sphere within which it is presented, instead than its logical construction. This is grounds that metphor use can act upon a individuals apprehension of a system. This is similar to the statement that different metaphors highlight facets of a system and do others more hard to see. For illustration when seeking to understand the basic rules of an electronic circuit, people understand different facets depending on whether they use the metaphor of fluxing H2O or of crowds of people traveling around the circuit. In Rumelhart and Norman & # 8217 ; s ( 1981 ) three theoretical accounts experiment to learn people about text processors. They used a secretary metaphor to demo how bids can be interspersed with text input, a card file metaphor to explicate the omission of a individual numbered line from a file, and a tape recording equipment metaphor described the demand for expressed eradicators in files. The metaphors had a mensurable consequence on the learnability of the text processor. Foss, Rossen & A ; Smith ( 1982 ) studied the undertaking of larning to utilize a text editor by novitiate users. Subjects presented with an progress organizer prior to the systems manual performed somewhat better than those who were non. The organiser topics required less clip to finish public presentation undertakings and used fewer bids. The progress organizer referred to a big extent to the thought of file booklets which are stored and retrieved from registering cabinets ; every bit good as explicating how the computing machine follows bids and can function as a tool. The illustrations in the paragraphs above demonstrate that metaphors have a mensurable consequence on acquisition, but they do non offer a definition of metaphor. How are we to recognize and cognize when metaphors have been created without a principled description of the functions between the beginning and mark spheres of the metaphor? Furthermore, how can we find how the metaphor operates in the head in existent fortunes, that is, find what sort of restraints controll the function? It would be utile to be able to supply a set of guidelines for, or even predict good metaphors, instead than merely being able to name them ad station facto. & # 8220 ; & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” & # 8221 ; ” In an effort to carry through this demand three chief theories of metaphor within the context of system and interface design have beed developed. Hammond & A ; Allinson ( 1987 ) establish their theory on Touangeau & A ; Sternberg & # 8217 ; s ( 1982 ) interactionist attack which recognises both lucifers and mismatches between the two spheres as contributing towards the metaphor. Metaphors are measured along two dimensions, range and degree of description. Scope refers to the figure of constructs the metaphor addresses. Command-driven systems, for illustration, typically have a big figure of metaphors of narrow range ; whereas the Unix hydraulic metaphor, tungsten

hich makes use of concepts such as pipe, is less restricted. The desktop metaphor is classed as having a wide scope and attempting to capture as much of the task it supports as possible. The level of description refers to the type of information a metaphor is expected to communicate. Hammond & Allinson appear principally concerned with task domain metaphors which aid the user’s understanding of tasks supported by the system. In the simple applications model which they propose they distinguish four levels: task, semantic, lexical and physical. As an example they give the metaphor of a tour around a given topic in an on line encyclopaedia. They suggest that the physical level, for example a commantry given by a guide, will be rejected, but other levels will be useful: At the task level, the user wants to find out about a topic that could plausibly be the subject of a tour; at the semantic level, the notion of a predetermined sequence of places maps well onto known or plausible system facilitates for viewing a series of displays; at the lexical level, the terminology of tours may relate to words or icons that the user may have noticed…people do not expect metaphors to explain everything. Nor may the absence of non-central features of the metaphor – such as a guide’s commentary – be important (H&A 1987, p80) Halasz & Moran (1982) distinguish conceptual models, analogies and metaphors. Conceptual models are intended as highly accurate, complete descriptions of a domain in some abstract format such as a graph or flow chart. Analogies involve structure mapping; at some level of abstraction the unknown system behaves the same way as the known system. Only part of an unknown system is similar to the known system in the case of metaphor, that is, only the most salient points of comparison. Halasz and Moran believe that analogies can cause faulty reasoning about a system and limit the view a user has of a system. They argue that conceptual models should be prefered for learning and suggest metaphors which explain just one or two aspects of a system (i.e. of narrow scope) may be useful. In contrast to this structural approach, which sees mismatches as potentially confusing, Carroll & Thomas (1982) and Carroll & Mack (1985) present what they call an active learning theory of metaphor, which involves a incremental process of association and consolidation of knowledge, guided and constrained by the user’s current task and goals. They see the indeterminate, incomplete nature of metaphor as promoting active and creative thought. The mind of the learner: takes an open-ended, incomplete – even indeterminate – kernel comparison, and makes it a focus for the self- initiated construction of new knowledge. (C&M 1985, p?) In the same vein they do not see mismatches to be necessarily problematic: Salient dissimilarities – in the context of salient similarities – stimulate thought and enhance the efficacy of the metaphor as a learning vehicle. (C&M 1985, p47) They thereby challenge Halasz & Moran’s opinion that conceptual models are good for supporting learning, saying that this embodies a passive learning theory where the learner has nothing left to do and consequently does not learn. The scope of this essay does not allow an indepth discussion of each theory, however based on the three theories there follows a discussion of important issues concerning the use of metaphors for users and designers. One highly relevant question is how to fit the metaphor to the user. Different user populations need different metaphors depending on their background knowledge. For example, CoSy, a conferencing system for distance learning, uses a system concept of the electronic campus shown in figure 1. The users of the system can roughly be divided into two groups: the academic staff and the students. The concept is seemingly intended to demonstrate how the system can be used and to shape the users’ attitude towards the system by use of a familiar concept in university education – the campus. This is perhaps a misconception: the campus will be familiar to the academic staff, but it may not be to the students, since they are, after all, involved in distance learning. Users also need different metaphors according to the amount of experience they have with computer systems. Novices with no prior experience will need metaphors based on non-computer domains; whereas those who do have prior experience can make use of metaphors which draw on this experience. For example, when creating a new version of a word processor the designer should obviously not present a whole set of new metaphors, but rather draw on and perhaps elaborate the existing ones. Considerations such as these can discipline and direct the designer and prevent the use of metaphors which although useful for the designer may make the system opaic to the user. The metaphor itself can act as a focus for design activities; it can be used to help define and structure facilities subsumed and excluded from it, as well as suggesting additional useful facilities otherwise overlooked. A further complex issue is how mismatches influence the use of a metaphor. Mismatches between the metaphor and the target domain can occur in either direction. Sometimes salient aspects of the metaphor do not map to the target domain, as in the typewriter where the majority of word processor keys behave like their typewriter equivalents except for the space bar. Halasz & Moran (1982) argue that this is a source of confusion for the learner and that it is better to use metaphors which just demonstrate one or two aspects of a system. This begs the question of how designers should signpost the boarders of a metaphor. Carroll & Thomson (1982) suggest that the user manual should “explicitly indicate to the user how the metaphor cannot be pushed too far”. Carroll & Mack (1985), in contrast, make the point, as already mentioned, that mismatches stimulate the user to learn about the system. Carroll, Mack & Kellog (1987) talk about the necessity of ensuring that the increase in complexity which this causes should not outweigh the benefits of the metaphor. Carroll & Mack are in favour of metaphors of broader scope rather than a collection of metaphors. They do point out, however, that it is sometimes not possible to cover all aspects of a system with a single metaphor. In such cases they suggest the metaphors should be taken from the same task domain, but care should be taken that their functions do not overlap. Hammond & Allinson (1987) warn against the attempt to adhere strictly to metaphors of wide scope across several levels of description and point out that this can make a system less flexible and more cumbersome (c.f. sifting through virtual office draws in a Spatial Data Management System). Instead they propose that the system should improve upon the metaphor and not be bounded by it: a metaphor can support partial mappings of knowledge with no ambiguity provided it is well chosen and provided the system is designed appropriately around it (H&A 1987, p87) Unfortunately they do not explain exactly how to achieve this. There are often important aspects of the target domain which do not map to the metaphor and are thus hidden. A metaphor of this type can cause a designer to fail to see important aspects of the task a system should support. This was a lethal error made by the designers of Cognoter, a “multi-user idea organising tool”, which led to “serious breakdowns in the system”(p54). Cognoter was used by people in the same room who could consequently see each other, but the textual component was designed around a “parcel post” model of communication. items are packaged and sent by the speaker, and then unpackaged and decoded by the reciever…if the reciever does not open his “mail” right away, he may end up with a bunch of stuff with no particular order. (p64) This metaphor entails that the “items” of communication are independent of people and temporal contexts. This masks other aspects of the communicative process and it was a failure to support these aspects which lead to communication problems. An interactive model of communication was subsequently adopted. This same masking effect can be a problem for users; the same metaphor which was initially useful in understanding the system can perhaps later become a barrier to further learning and prevent users exploiting the system to the full. The example of the electronic whiteboard given earlier is a case in point. It may not be obvious that the ideas saved on the board can be manipulated and reorganised, which is not the case with the real-world equivalent. Marshall, Nelson & Gardiner (1987b) also make this point: …by typing an interface to concepts which prevail in non-electronic environments, one is not taking full advantage of the benefits that can accrue from using the electronic medium…For example, a filing cabinet can be as restrictive as the real-life filing cabinet How can problems of this kind be overcome? The designer can highlight the provisional nature of metaphors and point out deviations from the real system at the time of initial learning and make the limits explicit. The designer should also keep in mind from the beginning that metaphors are presented to the user for an overview and may loose their usefulness with time. He or she could try to make them fit in with how a user eventually comes to conceptualize the system or task. The literature which exists on the subject of metaphor for users and designers of systems demonstrates that there do exist researches in the field of HCI who take metaphors seriously and current interest in virtual reality seems in turn to be stimulating interest in this area. However significant questions do remain. For example, can we predict a “good” metaphor? The answer is probably not. Hammond & Alinson (1987) develop an approximate model and Carroll, Mack & Kellog (1987) outline a structured methodology for designers to choose metaphors, although they admit that “there is a role for sheer invention” (C,M&K 1987, p78). An obvious question is whether metaphors are not perhaps the same thing as what most people would refer to as models (system models and user models). Perhaps in some respects they are. It is recognised that that models by their abstract nature are not complete and may require some degree of interpretation. However metaphors are not just incomplete; they are by definition partial/open-ended and even indeterminate. Models are often taken quite literally. An important point to remember about metaphors is that they are not intended to be taken literally. Margret Thatcher is not literally made of iron. In this respect metaphor possibly throws light on the way to view system concepts, that is, the concept of metaphor itself highlights the issues designers must consider, which may not otherwise be so obvious. The question is whether there is anything that it hides. Bibliography Carroll, J. M. & Mack, R. L. (1985). Metaphor, computing systems, and active learning, in International Journal of Man-Machine Studies, 22, 39-57 Carroll, J. M. & Thomas, J. C. (1982). Metaphor and the cognitive representation of computing systems, in IEEE Transactions on Systems, Man and Cybernetics, 12, 107-116 Carroll, J. M., Mack, R. L. & Kellog, W. A. (1988). Interface metaphors and user interface design, in Handbook of Human-Computer Interaction, M. Helander (ed), Elsevier Science Publishers, North Holland Gentner, D. (1980). The structure of analogical models in science. BBN Technical Report 4451 Halasz, F. & Moran, T. P. (1982). Analogy considered harmful, in Proceedings of the Conference on Human Factors in Computing Systems. Gaithersburg, Maryland, pp383-386 Hammond, N. V. & Allinson, L. J. (1987). The travel metaphor as design principle and training aid for navigating around complex systems, in People and Computers III, Diaper, D. & Winder, R. (eds) Jones, W. P. & Dumais, S. (1986). The spatial metaphor for user interfaces: Experimental test of reference by location versus naming. ACM Transactions on Office Information Systems, 4, 42-63 Mason, R. (1989). An evaluation of CoSy on an Open University course, in Mason, R. & Kaye, A. (eds). Mindweave: Communication, Computers and Distance Education. Oxford, Pergamon Press