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Lecture

UsersII.pdf

33 Pages
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Department
Information Technology
Course Code
ITEC 3230
Professor
Sotirios Liaskos

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Description
NTERACTION D ESIGN 1 Understanding Users: Part II Cognitive Frameworks O VERVIEW ¢Cognitive frameworks: —What they are and why we care about them. ¢Cognitive Frameworks: —Mental Models —Theory of Action —Information Processing —External Cognition —Distributed Cognition 2 C OGNITIVE F RAMEWORKS ¢ Framework: — A way by which we understand and talk about a particular domain. — Involves a set of core concepts, their meaning and use. ¢ Cognitive Frameworks — Frameworks about how the mind works. — Competing frameworks: ¢They all may have some degree of applicability. ¢Each offers a different point of view to the same phenomena. ¢Some are more recent and (as such) useful than others. ¢ Why frameworks — Give us an understanding of how users interact with their environment, understand systems, make decisions, organize their action etc. — We can use this to create better interfaces. 3 C OGNITIVE F RAMEWORKS ¢ Cognitive Frameworks to Discuss: — Internal Approaches —Focus on the mind in isolation. ¢Mental Models ¢How users understand the structure and the behavior of systems ¢Theory of Action ¢How action is sequentially organized to fulfill goals. ¢Information Processing ¢A modular view of cognitive processes. — External Approaches —Focus on the human in the world. ¢External Cognition ¢Taking into account external representation. ¢Distributed Cognition 4 ¢Considering cognitive phenomena across individuals, artifacts and representations. M ENTAL M ODELS ¢Users develop an understanding of a system through learning and using it ¢Knowledge is often described as a mental model —How to use the system (what to do next) —What to do with unfamiliar systems or unexpected situations (how the system works / is structured) ¢People make inferences using mental models of how to carry out tasks 5 M ENTAL M ODELS ¢Craik (1943) described mental models as internal constructions of some aspect of the external world enabling predictions to be made ¢Involves unconscious and conscious processes, where images and analogies are activated ¢Deep versus shallow models —Refers to the depth and accuracy of knowledge that we have about a systems. Eg. ¢What a passenger of an airplane knows about how it works vs. ¢What the pilot knows vs. 6 ¢What the engineer knows RIGHT AND W RONG M ENTAL M ODELS (aYou arrive home on a cold winter`s night to a cold house. How do you get the house to warm up as quickly as possible? Set the thermostat to be at its highest or to the desired temperature? (bYou arrive home starving hungry. You look in the fridge and find all that is left is an uncooked pizza. You have an electric oven. Do you warm it up to 375 degrees first and then put it in (as specified by the instructions) or turn the oven up higher to try to warm it up 7 quicker? RIGHT AND W RONG M ENTAL M ODELS ¢Many people have erroneous mental models (Kempton, 1996) ¢Why? —General valve theory, where ‘more is more’ principle is generalised to different settings (e.g. gas pedal, gas cooker, tap, radio volume) —Thermostats based on model of on-off switch model 8 R IGHT AND W RONG M ENTAL M ODELS ¢Same is often true for understanding how interactive devices and computers work: —Poor, often incomplete, easily confusable, based on inappropriate analogies and superstition (Norman, 1983) —e.g. elevators and pedestrian crossings - lot of people hit the button at least twice —Why? Think it will make the lights change faster or ensure the elevator arrives! 9 E VOKING THE RIGHT M ENTAL M ODELS ¢Have more transparent systems. —Alignment between the conceptual model and the user’s mental model. —How: ¢Feedback ¢Instructions, help and tutorials ¢Context-sensitive guidance ¢Clear conceptual model 10 N ORMAN ’ST HEORY O F A CTION ¢Proposes 7 stages of an activity —Establish a goal —Form an intention —Specify an action sequence —Execute an action —Perceive the system state —Interpret the state —Evaluate the system state with respect to the goals and intentions 11 N ORMAN ’ST HEORY O F A CTION ¢Proposes 7 stages of an activity —Establish a goal —Form an intention —Specify an action sequence —Execute an action —Perceive the system state —Interpret the state —Evaluate the system state with respect to the goals and intentions 12 T HEORY OF A CTION - E XAMPLE (i)  Set goal to find out about breaking news decide on news website (ii) Form an intention “check out CBC website” (iii)Specify what to do move cursor to link on browser (iv) Execute action sequence click on mouse button (v)  Check what happens at the interface see a new page pop up on the screen (vi) Interpret it read that it is the CBC website (vii)Evaluate it with respect to the goal 13 read breaking news T HEORY OF A CTION – W HY C ARE ? ¢Emphasizes on the cycles between user goals and system feedback. —You may want to minimize disturbances of those cycles. —E.g. catching the user’s attention with something irrelevant while they try to achieve a goal. —Help designers think about how to help users monitor their actions ¢How Realistic? —Human activity does not proceed in such an orderly and sequential manner —More usual for stages to be missed, repeated or out of order. —Do not always have a clear goal in mind but react to the world. —Theory is only approximation of what happens and is greatly simplified. 14 G ULF OF E XECUTION - GULF OF E VALUATION ¢Gulf of execution —User goals à [Intentions à Actions à I/face Mechanism] à System —The distance between what the user wants to achieve and what system offers to furn
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