The designer must ensure that the system image is

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Unformatted text preview: thout precise knowledge of the task due to 4 reasons: 1. Information is in the world: much of the information required to do the task can reside in the world. Behavior results from combining information in the head with information in the world. 2. Great precision is not required: precision, accuracy and completeness of knowledge are seldom required. Perfect behavior will happen if there is sufficient knowledge to distinguish the correct choice from the others. 3. Natural constraints are present. The world restricts the allowed behavior. The physical properties of objects constrain possible operations (ways we can use / manipulate objects). Each object has a set of physical features that limit its relationships to other objects, the operations that can be done on it, etc. 4. Cultural constraints are present. Society has evolved numerous artificial conventions that govern acceptable social behavior. These cultural conventions must be learned, but once learned apply to a wide variety of circumstances. These four reasons reduce the number of alternatives and reduce the amount of information required to be stored in memory to successfully complete the task. Memory is knowledge in the head • Often grouped into short term memory and long term memory • Three important categories of memory: o o Memory for meaningful relationships (with something else) o • Memory for arbitrary things (without meaning / relationships) Memory through explanation (some explanatory mechanism) Typically requires learning, is efficient, and not easily retrieved Memory is also knowledge in the world • Reminding (signal and a message) • Natural Mappings (arrangement, like stove controls example) • Typically easily retrieved whenever visible / audible, no learning required, but slowed up by the need to interpret the external information There are three aspects to mental models (types of conceptual models?): • the design model (the conceptualization the designer had in mind) • the user’s model (what the user develops to explain the operation of the system) • and the system image (the system’s appearance, operation, way it responds, manuals / instructions included with it) Ideally, the design model and user model are...
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This note was uploaded on 01/22/2014 for the course CMS 367 taught by Professor Browning during the Spring '08 term at University of Texas at Austin.

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