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Conscious vs subconscious deep narrow vs shallow

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Unformatted text preview: the same. The designer must ensure that the system image is consistent with and operates according to the proper conceptual model. Chapter 4: Knowing What to Do We mess up when there is more than one possibility / option of things to do Building the Lego motorcycle: semantic and cultural constraints, as well as the shape (clues) of the pieces allow us to figure out easily how the pieces are assembled together Constraints: Physical constraints – physical limitations, based on shape, size, etc. Semantic constraints – limitations based on the meaning of the situation (Lego motorcycle: rider must face forward… windshield goes in front of face, etc.) Cultural constraints – limitations based on accepted cultural conventions. (Lego motorcycle: signs are meant to be read, thus the ‘police’ sign should be right side up. The red light goes on the rear, because red is culturally defined to mean ‘stop’, etc.) Logical constraints – logically induced limitations (Lego motorcycle: all pieces should be used, with no gaps, etc.) Constraints are important in suggesting what we should do- so they should not be deceiving. An object should suggest (afford) what it does (only one predictable outcome- GOOD MAPPING). For example: an array of identical looking switches is a bad design While the above mainly focuses on constraints and mappings, we must remember to use good visibility and feedback. Crucial parts must be visible (doors must have door handles) and we need feedback to verify we completed the task successfully (a good display, showing what just happened) Chapter 5: To Err Is Human Language has built in functions to allow us to correct ourselves when we stumble, mess up, etc. Artificial devices often do not- a mistake can cause chaos. Slips are the most common error: when we intend to do one thing and accidentally do another (automatic behavior problem) Types of Slips: • Capture Errors (two action sequences have common initial stages - an alternative action 'captures' your attention) • Description Errors (two objects are physically alike enough to mess up - like throwing clothes in the toilet) • Data- Driven Errors (recalling the wrong...
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