Friday, October 23, 2009
The Design of Everyday things: Preface to the 2002 Edition
Dr. Norman was a cognitive scientist before he wrote the book. His interest gradually shifted towards usability/human errors after he and few of his colleagues examined the nuclear power plant accident at Three Mile Island in the United States and concluded that the fault laid in the design of the control room not the control room operators. He became interested in human error and hoped that his understanding of error would provide ways to teach people how to avoid mistakes. The author mentions that he spent some time in Cambridge England, at the Medical Research Council's world famous Applied Psychology Unit and was continually amused and frustrated by the workings of the building. He states that 'The Design of Everyday Thing' is the outcome of his frustration during his time in England.
The book was initially published with the title 'Psychology of Everyday Things' but was changed to 'Design of Everyday Things' (DOET) in the 2002 edition. The author says that the meaning was more meaningful and better conveyed the message of the book.The book covers mostly three critical topics. They are
- It is not your fault: According to the author, if you cannot figure out how to use a certain thing, it is not your fault, it's the design. Anything and everything should be clearly understandable to casual user if the design's purpose is to encourage use and efficiency
- The Power Of Observation: People learn a lot through observation. But the problem is you need to learn how to watch correctly.
- Design Principles: DOET contains several important design principles but the following are the short list of the most important ones
- Conceptual Model: We as a human being receive information, process it and respond accordingly. According to the author a good designed system should enable user to create the right conceptual model of the system.
- Feedback: Dr Norman believes that every system or application should provide user with some feedback for their action. A simple example could be taken of an online application form. The user should be provided with some feedback after they submit the form so that they are aware that the form has been submitted.
- Constraints: 'The surest way to make something easy to use, with few errors, is to make it impossible to do otherwise- to constrain the choices'. Dr Norman says that to prevent mistakes we should restrict the kind of interaction that can take place in an object. For example the car door should not be locked if we left our key inside the car. The designers should make sure when the keys are inside the ignition switch, the door cannot be locked.
- Affordance: Affordance refers to the perceived and actual properties of an object that gives clues to its operation. For example plates (on doors) are for pushing and knobs are for turning.
The Psychopathology of Everyday Things
The first chapter of POET starts off describing the importance of design. "Well designed objects are easy to understand. They contain visible clues to their operations. Poorly designed objects can be difficult and frustrating to use. They provide no clues or sometimes false clues." Norman introduces the term visibility here. The visibility of the product's controls and functions allows the user to map their relationships and see what the uses the product affords, something Norman calls a conceptual model/mental model. These models provide user with a clear idea of how the product should work.
Giving various examples on conceptual model and visibility Norman introduces two major design principles for understandability and usability in this chapter. They are:
1. Provide a good conceptual model
2. Make things visible
Giving the right conceptual model of a device or a product could be very tricky sometimes for the designers. Norman gives an example of his fridge at home. Norman says "control of refrigerator is made difficult because the manufacturer provides a false conceptual model. The fridge had only one thermostat and only one cooling mechanism for controlling the temperature. One control adjusts the thermostat setting, the other the relative proportion of cold air sent to each of the two compartments of refrigerator. The conceptual model provided by the manufacturer makes it difficult for users to use the product.
The user will have a mental model of how to use the object, and the object also yields a conceptual model (design model) for how it can be used. When the two models coincide, then there is a close "mapping". Norman writes that the designer usually expects the user's model to his design model, but this is obviously not always the case. Providing a good system image through documentations, instructions and labels act as a bridge between the design model and the user mental model.
Norman gives an example of a telephone to demonstrate poor visibility. Telephones today have lot of functions but are poorly designed. The functions are not easily visible for the users. Most users don't even realise that the functions are available. Norman says, "Whenever the number of possible actions exceeds the number of controls, there is apt to be difficulty". The telephone system has 24 functions, yet only fifteen controls and none of them labelled for specific action.
Lastly, Norman describes the principle of feedback. According to him, any action of a user should produce some feedback so the user can tell if the desired effect was achieved or not.
The first chapter of POET starts off describing the importance of design. "Well designed objects are easy to understand. They contain visible clues to their operations. Poorly designed objects can be difficult and frustrating to use. They provide no clues or sometimes false clues." Norman introduces the term visibility here. The visibility of the product's controls and functions allows the user to map their relationships and see what the uses the product affords, something Norman calls a conceptual model/mental model. These models provide user with a clear idea of how the product should work.
Giving various examples on conceptual model and visibility Norman introduces two major design principles for understandability and usability in this chapter. They are:
1. Provide a good conceptual model
2. Make things visible
Giving the right conceptual model of a device or a product could be very tricky sometimes for the designers. Norman gives an example of his fridge at home. Norman says "control of refrigerator is made difficult because the manufacturer provides a false conceptual model. The fridge had only one thermostat and only one cooling mechanism for controlling the temperature. One control adjusts the thermostat setting, the other the relative proportion of cold air sent to each of the two compartments of refrigerator. The conceptual model provided by the manufacturer makes it difficult for users to use the product.
The user will have a mental model of how to use the object, and the object also yields a conceptual model (design model) for how it can be used. When the two models coincide, then there is a close "mapping". Norman writes that the designer usually expects the user's model to his design model, but this is obviously not always the case. Providing a good system image through documentations, instructions and labels act as a bridge between the design model and the user mental model.
Norman gives an example of a telephone to demonstrate poor visibility. Telephones today have lot of functions but are poorly designed. The functions are not easily visible for the users. Most users don't even realise that the functions are available. Norman says, "Whenever the number of possible actions exceeds the number of controls, there is apt to be difficulty". The telephone system has 24 functions, yet only fifteen controls and none of them labelled for specific action.
Lastly, Norman describes the principle of feedback. According to him, any action of a user should produce some feedback so the user can tell if the desired effect was achieved or not.
// posted by Sumit @ 5:07 PM 
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