I. INTRODUCTIONIII. LEADING THE USER TO THE CORRECT OUTCOMEAffordancesVisibilityMapping and FeedbackIV. TOO MUCH KNOWLEDGE FOR THE USERDesign of User-Friendly SystemsJoel Clawson, Genevieve Hudak, Brock LaMeres, and Kitty Turner CSCI 7000 – Design, Learning, and CollaborationSpring 2004University of Colorado, BoulderI. INTRODUCTIONOver the past decade, the computer industry has experienced explosive growth.Advances in Integrated Circuit technology have allowed microprocessors to runextremely advanced software programs that are becoming present in all aspects of ourlives. Advances in mass storage elements such as hard disk drives and ROM’s haveafforded our society the ability to store all of our collective information in reasonableamounts of space. This information can be easily retrieved and added upon thanks to ourcontinual improvement of computer media. Finally, the creation of the Internet and theWorld Wide Web has given us the ability to communicate all of this information andcomputation power to all corners of the earth. Through computer media, our societynow has access to endless functionality and information. However, this brings us to aninteresting problem. How do we handle filtering endless functionality and unlimitedinformation to individuals who are trying to accomplish a specific task? The design ofUser-Friendly computer interfaces is one of the most challenging problems facingcomputer scientists today.To design better user interfaces, computer scientists must better understand theirusers. The designers of interface systems must study the psychology of the humanthought process. By understanding how users approach specific tasks, designers cantailor the interfaces to efficiently deliver the functionality and information that the user isafter. II. HUMANS WILL FIGURE IT OUTThe first concept that user interface designers must understand is that humanshave a problem solving approach to accomplishing tasks. When a user sits down at acomputer system, they know what task they want to accomplish. They have an inherentability to figure out the system. Users tend to figure out systems by observing whatfunctionality is presented to then and then forming a conceptual model of how the systemis going to work. Once the conceptual model is formed, they insert their task objectiveinto the model and conceive which action should be taken that would best deliver thedesired outcome. The user then takes that action, observes the outcome, and then makesa judgment on whether that action was correct or incorrect. Each action and observationeither reinforces or discredits the original conceptual model. This process is repeateduntil the end objective is accomplished.If designers understand this inherent behavior of users, then systems should bedesigned that will best compliment their user’s tendencies. In effect, computer scientistsshould design systems that will lead their users to the appropriate outcomes with the leastamount of time and effort that is possible. However, this is not a trivial task. Theinherent problem solving approach of humans creates a unique paradigm. Each user thatsits down at a computer system brings a different conceptual model of the system. Witheach action and observation, each unique conceptual model is refined in a different way.Users are easily and often lead down the incorrect path in a system because theirconceptual model is either wrong to begin with, or is conditioned to be wrong throughinappropriate actions and observations. III. LEADING THE USER TO THE CORRECT OUTCOMEOnce designers understand how users approach the system, the system can bedesigned to accommodate and constrain the user’s actions. This can be accomplished byexploiting affordances, visibility, mapping, and feedback.AffordancesThis term refers to the perceived properties of items. This is how the majority ofhumans think of how an object should work. For example, buttons should be pushed,knobs should be turned, etc… Relating this to the exploratory nature of users, designersmust consider that buttons will be pushed and knobs will be turned. A designer must becareful when giving users the opportunity to exploit features because by their very nature,they will!VisibilityThis refers to what functionality is obvious to the user. Users want to accomplishtheir tasks and are searching for actions to take in order to do this. Designers must makethe features that the user wants readily available and hide the advanced or dangerousfeatures so that users don’t have the opportunity to make mistakes.Mapping and FeedbackMapping refers to the causal relationship between an action and its outcome. Asstated before, the user is updating his conceptual model of the system based on a series ofactions and observations. Designers need to give feedback for each actions that is takento indicate to the user that he has actually performed an action. Just as important is togive the appropriate feedback so that the user maps the action to appropriate outcome.This is a delicate balance because if inappropriate feedback is given at the wrong time, auser can alter his conceptual model of the system in an incorrect fashion.IV. TOO MUCH KNOWLEDGE FOR THE USERAnother challenge to designers is how to handle the endless amount ofinformation that is available to users. We are now faced with knowledge that is in allcases overwhelming to humans. Designers must decided what information the user needsand which information can be stored in the system. This is sometimes called Knowledgein the World verses Knowledge in the Head. In general, designers should try to teachconcepts and models as opposed to raw data. Any knowledge that is discrete should bestored in the system. Examples of this are features lists, telephone numbers, maps, etc…Designers should concentrate on delivering the concept of the system to the user.Examples of this are where the feature lists are stored, how the telephone numbers areorganized, etc… When users understand how to the get the available information, notwhat the available information is, the amount of information that can be used is endless.V. GIVE THE USER A CHANCEThe final piece to user-friendly system design is to accept the fact that humanswill make errors. A common misconception that designers make is